129-580: Democritus ( / d ɪ ˈ m ɒ k r ɪ t ə s / , dim- OCK -rit-əs ; Greek : Δημόκριτος , Dēmókritos , meaning "chosen of the people"; c. 460 – c. 370 BC ) was an Ancient Greek pre-Socratic philosopher from Abdera , primarily remembered today for his formulation of an atomic theory of the universe . Democritus wrote extensively on a wide variety of topics. None of Democritus' original work has survived, except through second-hand references. Many of these references come from Aristotle , who viewed him as an important rival in
258-577: A basis for coinages: anthropology , photography , telephony , isomer , biomechanics , cinematography , etc. Together with Latin words , they form the foundation of international scientific and technical vocabulary ; for example, all words ending in -logy ('discourse'). There are many English words of Greek origin . Greek is an independent branch of the Indo-European language family. The ancient language most closely related to it may be ancient Macedonian , which, by most accounts,
387-480: A beginning and an end and that a world could be destroyed by collision with another world. Democritus was also a pioneer of mathematics and geometry in particular. According to Archimedes , Democritus was among the first to observe that a cone and pyramid with the same base area and height has one-third the volume of a cylinder or prism respectively, a result which Archimedes states was later proved by Eudoxus of Cnidus . Plutarch also reports that Democritus worked on
516-851: A collection of sayings ascribed to Democrates which some scholars including Diels and Kranz have also ascribed to Democritus. Diogenes Laertius claims that Plato disliked Democritus so much that he wished to have all of his books burned . He was nevertheless well known to his fellow northern-born philosopher Aristotle , and was the teacher of Protagoras . Democritus is evoked by English writer Samuel Johnson in his poem, The Vanity of Human Wishes (1749), ll. 49–68, and summoned to "arise on earth, /With chearful wisdom and instructive mirth, /See motley life in modern trappings dress'd, /And feed with varied fools th'eternal jest." Greek language Greek ( Modern Greek : Ελληνικά , romanized : Elliniká , [eliniˈka] ; Ancient Greek : Ἑλληνική , romanized : Hellēnikḗ )
645-410: A deficit or a surplus of electrons are called ions . Electrons that are farthest from the nucleus may be transferred to other nearby atoms or shared between atoms. By this mechanism, atoms are able to bond into molecules and other types of chemical compounds like ionic and covalent network crystals . By definition, any two atoms with an identical number of protons in their nuclei belong to
774-422: A different way, is internal conversion —a process that produces high-speed electrons that are not beta rays, followed by production of high-energy photons that are not gamma rays. A few large nuclei explode into two or more charged fragments of varying masses plus several neutrons, in a decay called spontaneous nuclear fission . Each radioactive isotope has a characteristic decay time period—the half-life —that
903-558: A fairly stable set of consonantal contrasts . The main phonological changes occurred during the Hellenistic and Roman period (see Koine Greek phonology for details): In all its stages, the morphology of Greek shows an extensive set of productive derivational affixes , a limited but productive system of compounding and a rich inflectional system. Although its morphological categories have been fairly stable over time, morphological changes are present throughout, particularly in
1032-560: A faster, more convenient cursive writing style with the use of ink and quill . The Greek alphabet consists of 24 letters, each with an uppercase ( majuscule ) and lowercase ( minuscule ) form. The letter sigma has an additional lowercase form (ς) used in the final position of a word: In addition to the letters, the Greek alphabet features a number of diacritical signs : three different accent marks ( acute , grave , and circumflex ), originally denoting different shapes of pitch accent on
1161-456: A finite set of orbits, and could jump between these orbits only in discrete changes of energy corresponding to absorption or radiation of a photon. This quantization was used to explain why the electrons' orbits are stable and why elements absorb and emit electromagnetic radiation in discrete spectra. Bohr's model could only predict the emission spectra of hydrogen, not atoms with more than one electron. Back in 1815, William Prout observed that
1290-540: A foreign language. It is also often stated that the historical changes have been relatively slight compared with some other languages. According to one estimation, " Homeric Greek is probably closer to Demotic than 12-century Middle English is to modern spoken English ". Greek is spoken today by at least 13 million people, principally in Greece and Cyprus along with a sizable Greek-speaking minority in Albania near
1419-529: A form of light but made of negatively charged particles because they can be deflected by electric and magnetic fields. He measured these particles to be at least a thousand times lighter than hydrogen (the lightest atom). He called these new particles corpuscles but they were later renamed electrons since these are the particles that carry electricity. Thomson also showed that electrons were identical to particles given off by photoelectric and radioactive materials. Thomson explained that an electric current
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#17327718158421548-419: A fractional electric charge. Protons are composed of two up quarks (each with charge + 2 / 3 ) and one down quark (with a charge of − 1 / 3 ). Neutrons consist of one up quark and two down quarks. This distinction accounts for the difference in mass and charge between the two particles. The quarks are held together by the strong interaction (or strong force), which
1677-484: A given accuracy in measuring a position one could only obtain a range of probable values for momentum, and vice versa. Thus, the planetary model of the atom was discarded in favor of one that described atomic orbital zones around the nucleus where a given electron is most likely to be found. This model was able to explain observations of atomic behavior that previous models could not, such as certain structural and spectral patterns of atoms larger than hydrogen. Though
1806-451: A mathematical function that characterises the probability that an electron appears to be at a particular location when its position is measured. Only a discrete (or quantized ) set of these orbitals exist around the nucleus, as other possible wave patterns rapidly decay into a more stable form. Orbitals can have one or more ring or node structures, and differ from each other in size, shape and orientation. Each atomic orbital corresponds to
1935-415: A particular energy level of the electron. The electron can change its state to a higher energy level by absorbing a photon with sufficient energy to boost it into the new quantum state. Likewise, through spontaneous emission , an electron in a higher energy state can drop to a lower energy state while radiating the excess energy as a photon. These characteristic energy values, defined by the differences in
2064-416: A passing and partial resemblance to the 19th-century understanding of atomic structure that has led some to regard Democritus as more of a scientist than other Greek philosophers; however, their ideas rested on very different bases. Democritus, along with Leucippus and Epicurus , proposed the earliest views on the shapes and connectivity of atoms. They reasoned that the solidness of the material corresponded to
2193-614: A problem involving the cross-section of a cone that Thomas Heath suggests may be an early version of infinitesimal calculus . Democritus thought that the first humans lived an anarchic and animal sort of life, foraging individually and living off the most palatable herbs and the fruit which grew wild on the trees, until fear of wild animals drove them together into societies. He believed that these early people had no language, but that they gradually began to articulate their expressions, establishing symbols for every sort of object, and in this manner came to understand each other. He says that
2322-552: A series of experiments in which they bombarded thin foils of metal with a beam of alpha particles . They did this to measure the scattering patterns of the alpha particles. They spotted a small number of alpha particles being deflected by angles greater than 90°. This shouldn't have been possible according to the Thomson model of the atom, whose charges were too diffuse to produce a sufficiently strong electric field. The deflections should have all been negligible. Rutherford proposed that
2451-519: A set of atomic numbers, from the single-proton element hydrogen up to the 118-proton element oganesson . All known isotopes of elements with atomic numbers greater than 82 are radioactive, although the radioactivity of element 83 ( bismuth ) is so slight as to be practically negligible. About 339 nuclides occur naturally on Earth , of which 251 (about 74%) have not been observed to decay, and are referred to as " stable isotopes ". Only 90 nuclides are stable theoretically , while another 161 (bringing
2580-472: A short-ranged attractive potential called the residual strong force . At distances smaller than 2.5 fm this force is much more powerful than the electrostatic force that causes positively charged protons to repel each other. Atoms of the same element have the same number of protons, called the atomic number . Within a single element, the number of neutrons may vary, determining the isotope of that element. The total number of protons and neutrons determine
2709-424: A single scientific explanation than become the king of Persia. Although many anecdotes about Democritus' life survive, their authenticity cannot be verified and modern scholars doubt their accuracy. Ancient accounts of his life have claimed that he lived to a very old age, with some writers claiming that he was over a hundred years old at the time of his death. Democritus wrote on ethics as well as physics. Democritus
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#17327718158422838-440: A size that is too small to be measured using available techniques. It was the lightest particle with a positive rest mass measured, until the discovery of neutrino mass. Under ordinary conditions, electrons are bound to the positively charged nucleus by the attraction created from opposite electric charges. If an atom has more or fewer electrons than its atomic number, then it becomes respectively negatively or positively charged as
2967-432: A tiny atomic nucleus , and are collectively called nucleons . The radius of a nucleus is approximately equal to 1.07 A 3 {\displaystyle 1.07{\sqrt[{3}]{A}}} femtometres , where A {\displaystyle A} is the total number of nucleons. This is much smaller than the radius of the atom, which is on the order of 10 fm. The nucleons are bound together by
3096-495: A void, but simply rejected the argument of Parmenides on the grounds that motion was an observable fact. Therefore, they asserted, there must be a void. Democritus held that originally the universe was composed of nothing but tiny atoms churning in chaos, until they collided together to form larger units—including the earth and everything on it. He surmised that there are many worlds , some growing, some decaying; some with no sun or moon, some with several. He held that every world has
3225-434: A whole. If an atom has more electrons than protons, then it has an overall negative charge, and is called a negative ion (or anion). Conversely, if it has more protons than electrons, it has a positive charge, and is called a positive ion (or cation). The electrons of an atom are attracted to the protons in an atomic nucleus by the electromagnetic force . The protons and neutrons in the nucleus are attracted to each other by
3354-470: A whole; a charged atom is called an ion . Electrons have been known since the late 19th century, mostly thanks to J.J. Thomson ; see history of subatomic physics for details. Protons have a positive charge and a mass of 1.6726 × 10 kg . The number of protons in an atom is called its atomic number . Ernest Rutherford (1919) observed that nitrogen under alpha-particle bombardment ejects what appeared to be hydrogen nuclei. By 1920 he had accepted that
3483-499: Is 29.5% nitrogen and 70.5% oxygen. Adjusting these figures, in nitrous oxide there is 80 g of oxygen for every 140 g of nitrogen, in nitric oxide there is about 160 g of oxygen for every 140 g of nitrogen, and in nitrogen dioxide there is 320 g of oxygen for every 140 g of nitrogen. 80, 160, and 320 form a ratio of 1:2:4. The respective formulas for these oxides are N 2 O , NO , and NO 2 . In 1897, J. J. Thomson discovered that cathode rays are not
3612-427: Is 88.1% tin and 11.9% oxygen, and the other is a white powder that is 78.7% tin and 21.3% oxygen. Adjusting these figures, in the grey powder there is about 13.5 g of oxygen for every 100 g of tin, and in the white powder there is about 27 g of oxygen for every 100 g of tin. 13.5 and 27 form a ratio of 1:2. Dalton concluded that in the grey oxide there is one atom of oxygen for every atom of tin, and in
3741-408: Is a measure of the distance out to which the electron cloud extends from the nucleus. This assumes the atom to exhibit a spherical shape, which is only obeyed for atoms in vacuum or free space. Atomic radii may be derived from the distances between two nuclei when the two atoms are joined in a chemical bond . The radius varies with the location of an atom on the atomic chart, the type of chemical bond,
3870-573: Is affected by the ratio of protons to neutrons, and also by the presence of certain "magic numbers" of neutrons or protons that represent closed and filled quantum shells. These quantum shells correspond to a set of energy levels within the shell model of the nucleus; filled shells, such as the filled shell of 50 protons for tin, confers unusual stability on the nuclide. Of the 251 known stable nuclides, only four have both an odd number of protons and odd number of neutrons: hydrogen-2 ( deuterium ), lithium-6 , boron-10 , and nitrogen-14 . ( Tantalum-180m
3999-454: Is also believed to impart some controversial advice such as " It is better not to have any children, for to bring them up well takes great trouble and care, and seeing them grow up badly is the cruellest of all pains ". He also wrote a treatise on the purpose of life and the nature of happiness. He held that " happiness was not to be found in riches but in the goods of the soul and one should not take pleasure in mortal things ". Another saying that
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4128-804: Is also found in Bulgaria near the Greek-Bulgarian border. Greek is also spoken worldwide by the sizable Greek diaspora which has notable communities in the United States , Australia , Canada , South Africa , Chile , Brazil , Argentina , Russia , Ukraine , the United Kingdom , and throughout the European Union , especially in Germany . Historically, significant Greek-speaking communities and regions were found throughout
4257-773: Is an Indo-European language, constituting an independent Hellenic branch within the Indo-European language family. It is native to Greece , Cyprus , Italy (in Calabria and Salento ), southern Albania , and other regions of the Balkans , Caucasus , the Black Sea coast, Asia Minor , and the Eastern Mediterranean . It has the longest documented history of any Indo-European language, spanning at least 3,400 years of written records. Its writing system
4386-479: Is an Indo-European language, but also includes a number of borrowings from the languages of the populations that inhabited Greece before the arrival of Proto-Greeks, some documented in Mycenaean texts ; they include a large number of Greek toponyms . The form and meaning of many words have changed. Loanwords (words of foreign origin) have entered the language, mainly from Latin, Venetian , and Turkish . During
4515-520: Is an inert solid that excludes other bodies from its volume and interacts with other atoms mechanically. Quantum-mechanical atoms are similar in that their motion can be described by mechanics in addition to their electric, magnetic and quantum interactions. They are different in that they can be split into protons, neutrons, and electrons. The elementary particles are similar to Democritean atoms in that they are indivisible but their collisions are governed purely by quantum physics . Fermions observe
4644-438: Is higher than its proton number, so Rutherford hypothesized that the surplus weight was carried by unknown particles with no electric charge and a mass equal to that of the proton. In 1928, Walter Bothe observed that beryllium emitted a highly penetrating, electrically neutral radiation when bombarded with alpha particles. It was later discovered that this radiation could knock hydrogen atoms out of paraffin wax . Initially it
4773-429: Is mediated by gluons . The protons and neutrons, in turn, are held to each other in the nucleus by the nuclear force , which is a residuum of the strong force that has somewhat different range-properties (see the article on the nuclear force for more). The gluon is a member of the family of gauge bosons , which are elementary particles that mediate physical forces. All the bound protons and neutrons in an atom make up
4902-481: Is not based on these old concepts. In the early 19th century, the scientist John Dalton found evidence that matter really is composed of discrete units, and so applied the word atom to those units. In the early 1800s, John Dalton compiled experimental data gathered by him and other scientists and discovered a pattern now known as the " law of multiple proportions ". He noticed that in any group of chemical compounds which all contain two particular chemical elements,
5031-425: Is not possible due to quantum effects . More than 99.9994% of an atom's mass is in the nucleus. Protons have a positive electric charge and neutrons have no charge, so the nucleus is positively charged. The electrons are negatively charged, and this opposing charge is what binds them to the nucleus. If the numbers of protons and electrons are equal, as they normally are, then the atom is electrically neutral as
5160-413: Is nothing—but a nothing cannot exist. The Parmenidean position was "You say there is a void; therefore the void is not nothing; therefore there is not the void." The position of Parmenides appeared validated by the observation that where there seems to be nothing there is air, and indeed even where there is not matter there is something , for instance light waves. The atomists agreed that motion required
5289-502: Is odd-odd and observationally stable, but is predicted to decay with a very long half-life.) Also, only four naturally occurring, radioactive odd-odd nuclides have a half-life over a billion years: potassium-40 , vanadium-50 , lanthanum-138 , and lutetium-176 . Most odd-odd nuclei are highly unstable with respect to beta decay , because the decay products are even-even, and are therefore more strongly bound, due to nuclear pairing effects . The large majority of an atom's mass comes from
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5418-494: Is often attributed to him is " The hopes of the educated were better than the riches of the ignorant ". He also stated that " the cause of sin is ignorance of what is better " which become a central notion later in the Socratic moral thought. Another idea he propounded which was later echoed in the Socratic moral thought was the maxim that " you are better off being wronged than doing wrong ". His other moral notions went contrary to
5547-519: Is protected and promoted officially as a regional and minority language in Armenia, Hungary , Romania, and Ukraine. It is recognized as a minority language and protected in Turkey by the 1923 Treaty of Lausanne . The phonology , morphology , syntax , and vocabulary of the language show both conservative and innovative tendencies across the entire attestation of the language from the ancient to
5676-477: Is required to bring them together. It is this energy-releasing process that makes nuclear fusion in stars a self-sustaining reaction. For heavier nuclei, the binding energy per nucleon begins to decrease. That means that a fusion process producing a nucleus that has an atomic number higher than about 26, and a mass number higher than about 60, is an endothermic process . Thus, more massive nuclei cannot undergo an energy-producing fusion reaction that can sustain
5805-455: Is responsible for most of the physical changes observed in nature. Chemistry is the science that studies these changes. The basic idea that matter is made up of tiny indivisible particles is an old idea that appeared in many ancient cultures. The word atom is derived from the ancient Greek word atomos , which means "uncuttable". But this ancient idea was based in philosophical reasoning rather than scientific reasoning. Modern atomic theory
5934-812: Is sometimes called aljamiado , as when Romance languages are written in the Arabic alphabet. Article 1 of the Universal Declaration of Human Rights in Greek: Transcription of the example text into Latin alphabet : Article 1 of the Universal Declaration of Human Rights in English: Proto-Greek Mycenaean Ancient Koine Medieval Modern Atom Atoms are
6063-526: Is spoken by at least 13.5 million people today in Greece, Cyprus, Italy, Albania, Turkey , and the many other countries of the Greek diaspora . Greek roots have been widely used for centuries and continue to be widely used to coin new words in other languages; Greek and Latin are the predominant sources of international scientific vocabulary . Greek has been spoken in the Balkan peninsula since around
6192-763: Is still used internationally for the writing of Ancient Greek . In Greek, the question mark is written as the English semicolon, while the functions of the colon and semicolon are performed by a raised point (•), known as the ano teleia ( άνω τελεία ). In Greek the comma also functions as a silent letter in a handful of Greek words, principally distinguishing ό,τι ( ó,ti , 'whatever') from ότι ( óti , 'that'). Ancient Greek texts often used scriptio continua ('continuous writing'), which means that ancient authors and scribes would write word after word with no spaces or punctuation between words to differentiate or mark boundaries. Boustrophedon , or bi-directional text,
6321-421: Is that an accelerating charged particle radiates electromagnetic radiation, causing the particle to lose kinetic energy. Circular motion counts as acceleration, which means that an electron orbiting a central charge should spiral down into that nucleus as it loses speed. In 1913, the physicist Niels Bohr proposed a new model in which the electrons of an atom were assumed to orbit the nucleus but could only do so in
6450-650: Is the Greek alphabet , which has been used for approximately 2,800 years; previously, Greek was recorded in writing systems such as Linear B and the Cypriot syllabary . The alphabet arose from the Phoenician script and was in turn the basis of the Latin , Cyrillic , Coptic , Gothic , and many other writing systems. The Greek language holds a very important place in the history of the Western world. Beginning with
6579-470: Is the mass loss and c is the speed of light . This deficit is part of the binding energy of the new nucleus, and it is the non-recoverable loss of the energy that causes the fused particles to remain together in a state that requires this energy to separate. The fusion of two nuclei that create larger nuclei with lower atomic numbers than iron and nickel —a total nucleon number of about 60—is usually an exothermic process that releases more energy than
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#17327718158426708-460: Is the passing of electrons from one atom to the next, and when there was no current the electrons embedded themselves in the atoms. This in turn meant that atoms were not indivisible as scientists thought. The atom was composed of electrons whose negative charge was balanced out by some source of positive charge to create an electrically neutral atom. Ions, Thomson explained, must be atoms which have an excess or shortage of electrons. The electrons in
6837-495: The Eastern Mediterranean , in what are today Southern Italy , Turkey , Cyprus , Syria , Lebanon , Israel , Palestine , Egypt , and Libya ; in the area of the Black Sea , in what are today Turkey, Bulgaria , Romania , Ukraine , Russia , Georgia , Armenia , and Azerbaijan ; and, to a lesser extent, in the Western Mediterranean in and around colonies such as Massalia , Monoikos , and Mainake . It
6966-516: The Indo-Iranian languages (see Graeco-Aryan ), but little definitive evidence has been found. In addition, Albanian has also been considered somewhat related to Greek and Armenian, and it has been proposed that they all form a higher-order subgroup along with other extinct languages of the ancient Balkans; this higher-order subgroup is usually termed Palaeo-Balkan , and Greek has a central position in it. Linear B , attested as early as
7095-561: The Pauli exclusion principle , which is similar to the Democritean principle that atoms exclude other bodies from their volume. However, bosons do not, with the prime example being the elementary particle photon . The theory of the atomists appears to be more nearly aligned with that of modern science than any other theory of antiquity. However, the similarity with modern concepts of science can be confusing when trying to understand where
7224-491: The Schroedinger equation , which describes electrons as three-dimensional waveforms rather than points in space. A consequence of using waveforms to describe particles is that it is mathematically impossible to obtain precise values for both the position and momentum of a particle at a given point in time. This became known as the uncertainty principle , formulated by Werner Heisenberg in 1927. In this concept, for
7353-438: The hydrostatic equilibrium of a star. The electrons in an atom are attracted to the protons in the nucleus by the electromagnetic force . This force binds the electrons inside an electrostatic potential well surrounding the smaller nucleus, which means that an external source of energy is needed for the electron to escape. The closer an electron is to the nucleus, the greater the attractive force. Hence electrons bound near
7482-492: The nominal and verbal systems. The major change in the nominal morphology since the classical stage was the disuse of the dative case (its functions being largely taken over by the genitive ). The verbal system has lost the infinitive , the synthetically -formed future, and perfect tenses and the optative mood . Many have been replaced by periphrastic ( analytical ) forms. Pronouns show distinctions in person (1st, 2nd, and 3rd), number (singular, dual , and plural in
7611-547: The nuclear force . This force is usually stronger than the electromagnetic force that repels the positively charged protons from one another. Under certain circumstances, the repelling electromagnetic force becomes stronger than the nuclear force. In this case, the nucleus splits and leaves behind different elements . This is a form of nuclear decay . Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals . The ability of atoms to attach and detach from each other
7740-421: The nuclide . The number of neutrons relative to the protons determines the stability of the nucleus, with certain isotopes undergoing radioactive decay . The proton, the electron, and the neutron are classified as fermions . Fermions obey the Pauli exclusion principle which prohibits identical fermions, such as multiple protons, from occupying the same quantum state at the same time. Thus, every proton in
7869-462: The 'surface' of these particles is not sharply defined. The neutron was discovered in 1932 by the English physicist James Chadwick . In the Standard Model of physics, electrons are truly elementary particles with no internal structure, whereas protons and neutrons are composite particles composed of elementary particles called quarks . There are two types of quarks in atoms, each having
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#17327718158427998-470: The 3rd millennium BC, or possibly earlier. The earliest written evidence is a Linear B clay tablet found in Messenia that dates to between 1450 and 1350 BC, making Greek the world's oldest recorded living language . Among the Indo-European languages, its date of earliest written attestation is matched only by the now-extinct Anatolian languages . The Greek language is conventionally divided into
8127-486: The Greek alphabet since approximately the 9th century BC. It was created by modifying the Phoenician alphabet , with the innovation of adopting certain letters to represent the vowels. The variant of the alphabet in use today is essentially the late Ionic variant, introduced for writing classical Attic in 403 BC. In classical Greek, as in classical Latin, only upper-case letters existed. The lower-case Greek letters were developed much later by medieval scribes to permit
8256-425: The Greek language are often emphasized. Although Greek has undergone morphological and phonological changes comparable to those seen in other languages, never since classical antiquity has its cultural, literary, and orthographic tradition been interrupted to the extent that one can speak of a new language emerging. Greek speakers today still tend to regard literary works of ancient Greek as part of their own rather than
8385-495: The Greek language was the Cypriot syllabary (also a descendant of Linear A via the intermediate Cypro-Minoan syllabary ), which is closely related to Linear B but uses somewhat different syllabic conventions to represent phoneme sequences. The Cypriot syllabary is attested in Cyprus from the 11th century BC until its gradual abandonment in the late Classical period, in favor of the standard Greek alphabet. Greek has been written in
8514-629: The Greek verb have likewise remained largely the same over the course of the language's history but with significant changes in the number of distinctions within each category and their morphological expression. Greek verbs have synthetic inflectional forms for: Many aspects of the syntax of Greek have remained constant: verbs agree with their subject only, the use of the surviving cases is largely intact (nominative for subjects and predicates, accusative for objects of most verbs and many prepositions, genitive for possessors), articles precede nouns, adpositions are largely prepositional, relative clauses follow
8643-685: The Greek-Albanian border. A significant percentage of Albania's population has knowledge of the Greek language due in part to the Albanian wave of immigration to Greece in the 1980s and '90s and the Greek community in the country. Prior to the Greco-Turkish War and the resulting population exchange in 1923 a very large population of Greek-speakers also existed in Turkey , though very few remain today. A small Greek-speaking community
8772-404: The acute during the late 20th century, and it has only been retained in typography . After the writing reform of 1982, most diacritics are no longer used. Since then, Greek has been written mostly in the simplified monotonic orthography (or monotonic system), which employs only the acute accent and the diaeresis. The traditional system, now called the polytonic orthography (or polytonic system),
8901-399: The amount of Element A per measure of Element B will differ across these compounds by ratios of small whole numbers. This pattern suggested that each element combines with other elements in multiples of a basic unit of weight, with each element having a unit of unique weight. Dalton decided to call these units "atoms". For example, there are two types of tin oxide : one is a grey powder that
9030-402: The ancient language; singular and plural alone in later stages), and gender (masculine, feminine, and neuter), and decline for case (from six cases in the earliest forms attested to four in the modern language). Nouns, articles, and adjectives show all the distinctions except for a person. Both attributive and predicative adjectives agree with the noun. The inflectional categories of
9159-444: The atom logically had to be balanced out by a commensurate amount of positive charge, but Thomson had no idea where this positive charge came from, so he tentatively proposed that it was everywhere in the atom, the atom being in the shape of a sphere. This was the mathematically simplest hypothesis to fit the available evidence, or lack thereof. Following from this, Thomson imagined that the balance of electrostatic forces would distribute
9288-422: The atomic mass unit (for example the mass of a nitrogen-14 is roughly 14 Da), but this number will not be exactly an integer except (by definition) in the case of carbon-12. The heaviest stable atom is lead-208, with a mass of 207.976 6521 Da . As even the most massive atoms are far too light to work with directly, chemists instead use the unit of moles . One mole of atoms of any element always has
9417-491: The atomic weights of many elements were multiples of hydrogen's atomic weight, which is in fact true for all of them if one takes isotopes into account. In 1898, J. J. Thomson found that the positive charge of a hydrogen ion is equal to the negative charge of an electron, and these were then the smallest known charged particles. Thomson later found that the positive charge in an atom is a positive multiple of an electron's negative charge. In 1913, Henry Moseley discovered that
9546-412: The basic particles of the chemical elements . An atom consists of a nucleus of protons and generally neutrons , surrounded by an electromagnetically bound swarm of electrons . The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium , and any atom that contains 29 protons is copper . Atoms with
9675-413: The center of the potential well require more energy to escape than those at greater separations. Electrons, like other particles, have properties of both a particle and a wave . The electron cloud is a region inside the potential well where each electron forms a type of three-dimensional standing wave —a wave form that does not move relative to the nucleus. This behavior is defined by an atomic orbital ,
9804-478: The chemical elements, at least one stable isotope exists. As a rule, there is only a handful of stable isotopes for each of these elements, the average being 3.1 stable isotopes per element. Twenty-six " monoisotopic elements " have only a single stable isotope, while the largest number of stable isotopes observed for any element is ten, for the element tin . Elements 43 , 61 , and all elements numbered 83 or higher have no stable isotopes. Stability of isotopes
9933-453: The core of the Sun protons require energies of 3 to 10 keV to overcome their mutual repulsion—the coulomb barrier —and fuse together into a single nucleus. Nuclear fission is the opposite process, causing a nucleus to split into two smaller nuclei—usually through radioactive decay. The nucleus can also be modified through bombardment by high energy subatomic particles or photons. If this modifies
10062-456: The earliest men lived laboriously, having none of the utilities of life; clothing, houses, fire, domestication, and farming were unknown to them. Democritus presents the early period of mankind as one of learning by trial and error, and says that each step slowly led to more discoveries; they took refuge in the caves in winter, stored fruits that could be preserved, and through reason and keenness of mind came to build upon each new idea. Democritus
10191-404: The early 19th century that was used for literary and official purposes in the newly formed Greek state. In 1976, Dimotiki was declared the official language of Greece, after having incorporated features of Katharevousa and thus giving birth to Standard Modern Greek , used today for all official purposes and in education . The historical unity and continuing identity between the various stages of
10320-512: The electrons throughout the sphere in a more or less even manner. Thomson's model is popularly known as the plum pudding model , though neither Thomson nor his colleagues used this analogy. Thomson's model was incomplete, it was unable to predict any other properties of the elements such as emission spectra and valencies . It was soon rendered obsolete by the discovery of the atomic nucleus . Between 1908 and 1913, Ernest Rutherford and his colleagues Hans Geiger and Ernest Marsden performed
10449-506: The energies of the quantum states, are responsible for atomic spectral lines . The amount of energy needed to remove or add an electron—the electron binding energy —is far less than the binding energy of nucleons . For example, it requires only 13.6 eV to strip a ground-state electron from a hydrogen atom, compared to 2.23 million eV for splitting a deuterium nucleus. Atoms are electrically neutral if they have an equal number of protons and electrons. Atoms that have either
10578-671: The energies of the recoiling charged particles, he deduced that the radiation was actually composed of electrically neutral particles which could not be massless like the gamma ray, but instead were required to have a mass similar to that of a proton. Chadwick now claimed these particles as Rutherford's neutrons. In 1925, Werner Heisenberg published the first consistent mathematical formulation of quantum mechanics ( matrix mechanics ). One year earlier, Louis de Broglie had proposed that all particles behave like waves to some extent, and in 1926 Erwin Schroedinger used this idea to develop
10707-618: The epics of Homer , ancient Greek literature includes many works of lasting importance in the European canon . Greek is also the language in which many of the foundational texts in science and philosophy were originally composed. The New Testament of the Christian Bible was also originally written in Greek. Together with the Latin texts and traditions of the Roman world , the Greek texts and Greek societies of antiquity constitute
10836-561: The field of natural philosophy . He was known in antiquity as the ‘laughing philosopher’ because of his emphasis on the value of cheerfulness. Democritus was born in Abdera, on the coast of Thrace . He was a polymath and prolific writer, producing nearly eighty treatises on subjects such as poetry, harmony, military tactics, and Babylonian theology. He traveled extensively, visiting Egypt and Persia, but wasn't particularly impressed by these countries. He once remarked that he would rather uncover
10965-452: The following periods: In the modern era, the Greek language entered a state of diglossia : the coexistence of vernacular and archaizing written forms of the language. What came to be known as the Greek language question was a polarization between two competing varieties of Modern Greek: Dimotiki , the vernacular form of Modern Greek proper, and Katharevousa , meaning 'purified', a compromise between Dimotiki and Ancient Greek developed in
11094-433: The frequencies of X-ray emissions from an excited atom were a mathematical function of its atomic number and hydrogen's nuclear charge. In 1919 Rutherford bombarded nitrogen gas with alpha particles and detected hydrogen ions being emitted from the gas, and concluded that they were produced by alpha particles hitting and splitting the nuclei of the nitrogen atoms. These observations led Rutherford to conclude that
11223-416: The hydrogen nucleus is a distinct particle within the atom and named it proton . Neutrons have no electrical charge and have a mass of 1.6749 × 10 kg . Neutrons are the heaviest of the three constituent particles, but their mass can be reduced by the nuclear binding energy . Neutrons and protons (collectively known as nucleons ) have comparable dimensions—on the order of 2.5 × 10 m —although
11352-445: The hydrogen nucleus is a singular particle with a positive charge equal to the electron's negative charge. He named this particle " proton " in 1920. The number of protons in an atom (which Rutherford called the " atomic number " ) was found to be equal to the element's ordinal number on the periodic table and therefore provided a simple and clear-cut way of distinguishing the elements from each other. The atomic weight of each element
11481-407: The hypothesis came from. Classical atomists could not have had an empirical basis for modern concepts of atoms and molecules. The atomistic void hypothesis was a response to the paradoxes of Parmenides and Zeno , the founders of metaphysical logic, who put forth difficult-to-answer arguments in favor of the idea that there can be no movement. They held that any movement would require a void—which
11610-439: The infinitive entirely (employing a raft of new periphrastic constructions instead) and uses participles more restrictively. The loss of the dative led to a rise of prepositional indirect objects (and the use of the genitive to directly mark these as well). Ancient Greek tended to be verb-final, but neutral word order in the modern language is VSO or SVO. Modern Greek inherits most of its vocabulary from Ancient Greek, which in turn
11739-467: The late 15th century BC, was the first script used to write Greek. It is basically a syllabary , which was finally deciphered by Michael Ventris and John Chadwick in the 1950s (its precursor, Linear A , has not been deciphered and most likely encodes a non-Greek language). The language of the Linear B texts, Mycenaean Greek , is the earliest known form of Greek. Another similar system used to write
11868-640: The membership of Greece and Cyprus in the European Union, Greek is one of the organization's 24 official languages . Greek is recognized as a minority language in Albania, and used co-officially in some of its municipalities, in the districts of Gjirokastër and Sarandë . It is also an official minority language in the regions of Apulia and Calabria in Italy. In the framework of the European Charter for Regional or Minority Languages , Greek
11997-441: The modern period. The division into conventional periods is, as with all such periodizations, relatively arbitrary, especially because, in all periods, Ancient Greek has enjoyed high prestige, and the literate borrowed heavily from it. Across its history, the syllabic structure of Greek has varied little: Greek shows a mixed syllable structure, permitting complex syllabic onsets but very restricted codas. It has only oral vowels and
12126-432: The mutual repulsion of the protons requires an increasing proportion of neutrons to maintain the stability of the nucleus. The number of protons and neutrons in the atomic nucleus can be modified, although this can require very high energies because of the strong force. Nuclear fusion occurs when multiple atomic particles join to form a heavier nucleus, such as through the energetic collision of two nuclei. For example, at
12255-399: The noun they modify and relative pronouns are clause-initial. However, the morphological changes also have their counterparts in the syntax, and there are also significant differences between the syntax of the ancient and that of the modern form of the language . Ancient Greek made great use of participial constructions and of constructions involving the infinitive, and the modern variety lacks
12384-509: The nucleus must occupy a quantum state different from all other protons, and the same applies to all neutrons of the nucleus and to all electrons of the electron cloud. A nucleus that has a different number of protons than neutrons can potentially drop to a lower energy state through a radioactive decay that causes the number of protons and neutrons to more closely match. As a result, atoms with matching numbers of protons and neutrons are more stable against decay, but with increasing atomic number,
12513-515: The nucleus to emit particles or electromagnetic radiation. Radioactivity can occur when the radius of a nucleus is large compared with the radius of the strong force, which only acts over distances on the order of 1 fm. The most common forms of radioactive decay are: Other more rare types of radioactive decay include ejection of neutrons or protons or clusters of nucleons from a nucleus, or more than one beta particle . An analog of gamma emission which allows excited nuclei to lose energy in
12642-453: The number of hydrogen atoms. A single carat diamond with a mass of 2 × 10 kg contains about 10 sextillion (10 ) atoms of carbon . If an apple were magnified to the size of the Earth, then the atoms in the apple would be approximately the size of the original apple. Every element has one or more isotopes that have unstable nuclei that are subject to radioactive decay, causing
12771-450: The number of neighboring atoms ( coordination number ) and a quantum mechanical property known as spin . On the periodic table of the elements, atom size tends to increase when moving down columns, but decrease when moving across rows (left to right). Consequently, the smallest atom is helium with a radius of 32 pm , while one of the largest is caesium at 225 pm. When subjected to external forces, like electrical fields ,
12900-451: The number of protons in a nucleus, the atom changes to a different chemical element. If the mass of the nucleus following a fusion reaction is less than the sum of the masses of the separate particles, then the difference between these two values can be emitted as a type of usable energy (such as a gamma ray , or the kinetic energy of a beta particle ), as described by Albert Einstein 's mass–energy equivalence formula, E=mc , where m
13029-536: The objects of study of the discipline of Classics . During antiquity , Greek was by far the most widely spoken lingua franca in the Mediterranean world . It eventually became the official language of the Byzantine Empire and developed into Medieval Greek . In its modern form , Greek is the official language of Greece and Cyprus and one of the 24 official languages of the European Union . It
13158-706: The older periods of Greek, loanwords into Greek acquired Greek inflections, thus leaving only a foreign root word. Modern borrowings (from the 20th century on), especially from French and English, are typically not inflected; other modern borrowings are derived from Albanian , South Slavic ( Macedonian / Bulgarian ) and Eastern Romance languages ( Aromanian and Megleno-Romanian ). Greek words have been widely borrowed into other languages, including English. Example words include: mathematics , physics , astronomy , democracy , philosophy , athletics , theatre, rhetoric , baptism , evangelist , etc. Moreover, Greek words and word elements continue to be productive as
13287-451: The philosopher's oeuvre which had belonged to aesthetics as a discipline, but only fragments of the relevant works are extant; hence of all Democritus writings on these matters, only a small percentage of his thoughts and ideas can be known. Diogenes Laertius attributes several works to Democritus, but none of them have survived in a complete form. A collections of sayings credited to Democritus have been preserved by Stobaeus , as well as
13416-435: The positive charge of the atom is concentrated in a tiny volume at the center of the atom and that the electrons surround this nucleus in a diffuse cloud. This nucleus carried almost all of the atom's mass, the electrons being so very light. Only such an intense concentration of charge, anchored by its high mass, could produce an electric field that could deflect the alpha particles so strongly. A problem in classical mechanics
13545-448: The protons and neutrons that make it up. The total number of these particles (called "nucleons") in a given atom is called the mass number . It is a positive integer and dimensionless (instead of having dimension of mass), because it expresses a count. An example of use of a mass number is "carbon-12," which has 12 nucleons (six protons and six neutrons). The actual mass of an atom at rest is often expressed in daltons (Da), also called
13674-421: The red powder there is about 42 g of oxygen for every 100 g of iron. 28 and 42 form a ratio of 2:3. Dalton concluded that in these oxides, for every two atoms of iron, there are two or three atoms of oxygen respectively ( Fe 2 O 2 and Fe 2 O 3 ). As a final example: nitrous oxide is 63.3% nitrogen and 36.7% oxygen, nitric oxide is 44.05% nitrogen and 55.95% oxygen, and nitrogen dioxide
13803-412: The same chemical element . Atoms with equal numbers of protons but a different number of neutrons are different isotopes of the same element. For example, all hydrogen atoms admit exactly one proton, but isotopes exist with no neutrons ( hydrogen-1 , by far the most common form, also called protium), one neutron ( deuterium ), two neutrons ( tritium ) and more than two neutrons . The known elements form
13932-498: The same number of atoms (about 6.022 × 10 ). This number was chosen so that if an element has an atomic mass of 1 u, a mole of atoms of that element has a mass close to one gram. Because of the definition of the unified atomic mass unit , each carbon-12 atom has an atomic mass of exactly 12 Da, and so a mole of carbon-12 atoms weighs exactly 0.012 kg. Atoms lack a well-defined outer boundary, so their dimensions are usually described in terms of an atomic radius . This
14061-448: The same number of protons but a different number of neutrons are called isotopes of the same element. Atoms are extremely small, typically around 100 picometers across. A human hair is about a million carbon atoms wide. Atoms are smaller than the shortest wavelength of visible light, which means humans cannot see atoms with conventional microscopes. They are so small that accurately predicting their behavior using classical physics
14190-416: The senses; they are infinite in numbers and come in infinitely many varieties, and they have existed forever and that these atoms are in constant motion in the void or vacuum. The middle-sized objects of everyday life are complexes of atoms that are brought together by random collisions, differing in kind based on the variations among their constituent atoms. For Democritus, the only true realities are atoms and
14319-539: The shape of an atom may deviate from spherical symmetry . The deformation depends on the field magnitude and the orbital type of outer shell electrons, as shown by group-theoretical considerations. Aspherical deviations might be elicited for instance in crystals , where large crystal-electrical fields may occur at low-symmetry lattice sites. Significant ellipsoidal deformations have been shown to occur for sulfur ions and chalcogen ions in pyrite -type compounds. Atomic dimensions are thousands of times smaller than
14448-416: The shape of the atoms involved. Using analogies from humans' sense experiences , he gave a picture or an image of an atom that distinguished them from each other by their shape, their size, and the arrangement of their parts. Moreover, connections were explained by material links in which single atoms were supplied with attachments: some with hooks and eyes, others with balls and sockets. The Democritean atom
14577-437: The stressed vowel; the so-called breathing marks ( rough and smooth breathing ), originally used to signal presence or absence of word-initial /h/; and the diaeresis , used to mark the full syllabic value of a vowel that would otherwise be read as part of a diphthong. These marks were introduced during the course of the Hellenistic period. Actual usage of the grave in handwriting saw a rapid decline in favor of uniform usage of
14706-514: The then prevalent views such as his idea that " A good person not only refrains from wrongdoing but does not even want to do wrong. " for the generally held notion back then was that virtue reaches it apex when it triumphs over conflicting human passions. Later Greek historians consider Democritus to have established aesthetics as a subject of investigation and study, as he wrote theoretically on poetry and fine art long before authors such as Aristotle . Specifically, Thrasyllus identified six works in
14835-737: The total to 251) have not been observed to decay, even though in theory it is energetically possible. These are also formally classified as "stable". An additional 35 radioactive nuclides have half-lives longer than 100 million years, and are long-lived enough to have been present since the birth of the Solar System . This collection of 286 nuclides are known as primordial nuclides . Finally, an additional 53 short-lived nuclides are known to occur naturally, as daughter products of primordial nuclide decay (such as radium from uranium ), or as products of natural energetic processes on Earth, such as cosmic ray bombardment (for example, carbon-14). For 80 of
14964-445: The unified atomic mass unit (u). This unit is defined as a twelfth of the mass of a free neutral atom of carbon-12 , which is approximately 1.66 × 10 kg . Hydrogen-1 (the lightest isotope of hydrogen which is also the nuclide with the lowest mass) has an atomic weight of 1.007825 Da. The value of this number is called the atomic mass . A given atom has an atomic mass approximately equal (within 1%) to its mass number times
15093-433: The vacuum were the beginning of the universe; and that everything else existed only in opinion. (trans. Yonge 1853) He concluded that divisibility of matter comes to an end, and the smallest possible fragments must be bodies with sizes and shapes, although the exact argument for this conclusion of his is not known. The smallest and indivisible bodies he called "atoms." Atoms, Democritus believed, are too small to be detected by
15222-535: The void. What we perceive as water, fire, plants, or humans are merely combinations of atoms in the void. The sensory qualities we experience are not real; they exist only by convention. Of the mass of atoms, Democritus said, "The more any indivisible exceeds, the heavier it is." However, his exact position on atomic weight is disputed. His exact contributions are difficult to disentangle from those of his mentor Leucippus , as they are often mentioned together in texts. Their speculation on atoms, taken from Leucippus, bears
15351-406: The wavelengths of light (400–700 nm ) so they cannot be viewed using an optical microscope , although individual atoms can be observed using a scanning tunneling microscope . To visualize the minuteness of the atom, consider that a typical human hair is about 1 million carbon atoms in width. A single drop of water contains about 2 sextillion ( 2 × 10 ) atoms of oxygen, and twice
15480-432: The white oxide there are two atoms of oxygen for every atom of tin ( SnO and SnO 2 ). Dalton also analyzed iron oxides . There is one type of iron oxide that is a black powder which is 78.1% iron and 21.9% oxygen; and there is another iron oxide that is a red powder which is 70.4% iron and 29.6% oxygen. Adjusting these figures, in the black powder there is about 28 g of oxygen for every 100 g of iron, and in
15609-407: The word atom originally denoted a particle that cannot be cut into smaller particles, in modern scientific usage the atom is composed of various subatomic particles . The constituent particles of an atom are the electron , the proton and the neutron . The electron is the least massive of these particles by four orders of magnitude at 9.11 × 10 kg , with a negative electrical charge and
15738-574: Was a distinct dialect of Greek itself. Aside from the Macedonian question, current consensus regards Phrygian as the closest relative of Greek, since they share a number of phonological, morphological and lexical isoglosses , with some being exclusive between them. Scholars have proposed a Graeco-Phrygian subgroup out of which Greek and Phrygian originated. Among living languages, some Indo-Europeanists suggest that Greek may be most closely related to Armenian (see Graeco-Armenian ) or
15867-541: Was a student of Leucippus . Early sources such as Aristotle and Theophrastus credit Leucippus with creating atomism and sharing its ideas with Democritus, but later sources credit only Democritus, making it hard to distinguish their individual contributions. We have various quotes from Democritus on atoms, one of them being: δοκεῖ δὲ αὐτῶι τάδε· ἀρχὰς εἶναι τῶν ὅλων ἀτόμους καὶ κενόν, τὰ δ'ἀλλα πάντα νενομίσθαι [δοξάζεσθαι]. (Diogenes Laërtius, Democritus, Vol. IX, 44) Now his principal doctrines were these. That atoms and
15996-568: Was also used as the official language of government and religion in the Christian Nubian kingdoms , for most of their history. Greek, in its modern form, is the official language of Greece, where it is spoken by almost the entire population. It is also the official language of Cyprus (nominally alongside Turkish ) and the British Overseas Territory of Akrotiri and Dhekelia (alongside English ). Because of
16125-557: Was also used in Ancient Greek. Greek has occasionally been written in the Latin script , especially in areas under Venetian rule or by Greek Catholics . The term Frankolevantinika / Φραγκολεβαντίνικα applies when the Latin script is used to write Greek in the cultural ambit of Catholicism (because Frankos / Φράγκος is an older Greek term for West-European dating to when most of (Roman Catholic Christian) West Europe
16254-506: Was eloquent on ethical topics. Some sixty pages of his fragments, as recorded in Diels–Kranz , are devoted to moral counsel. The ethics and politics of Democritus come to us mostly in the form of maxims. In placing the quest for happiness at the center of moral philosophy, he was followed by almost every moralist of antiquity. The most common maxims associated with him are " Accept favours only if you plan to do greater favours in return ", and he
16383-432: Was thought to be high-energy gamma radiation , since gamma radiation had a similar effect on electrons in metals, but James Chadwick found that the ionization effect was too strong for it to be due to electromagnetic radiation, so long as energy and momentum were conserved in the interaction. In 1932, Chadwick exposed various elements, such as hydrogen and nitrogen, to the mysterious "beryllium radiation", and by measuring
16512-580: Was under the control of the Frankish Empire ). Frankochiotika / Φραγκοχιώτικα (meaning 'Catholic Chiot') alludes to the significant presence of Catholic missionaries based on the island of Chios . Additionally, the term Greeklish is often used when the Greek language is written in a Latin script in online communications. The Latin script is nowadays used by the Greek-speaking communities of Southern Italy . The Yevanic dialect
16641-673: Was written by Romaniote and Constantinopolitan Karaite Jews using the Hebrew Alphabet . In a tradition, that in modern time, has come to be known as Greek Aljamiado , some Greek Muslims from Crete wrote their Cretan Greek in the Arabic alphabet . The same happened among Epirote Muslims in Ioannina . This also happened among Arabic-speaking Byzantine rite Christians in the Levant ( Lebanon , Palestine, and Syria ). This usage
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