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110-445: Chemists use their knowledge to learn the composition and properties of unfamiliar substances, as well as to reproduce and synthesize large quantities of useful naturally occurring substances and create new artificial substances and useful processes. Chemists may specialize in any number of subdisciplines of chemistry . Materials scientists and metallurgists share much of the same education and skills with chemists. The work of chemists

220-440: A chemical equation . While in a non-nuclear chemical reaction the number and kind of atoms on both sides of the equation are equal, for a nuclear reaction this holds true only for the nuclear particles viz. protons and neutrons. The sequence of steps in which the reorganization of chemical bonds may be taking place in the course of a chemical reaction is called its mechanism . A chemical reaction can be envisioned to take place in

330-510: A financial crisis , an external trade shock, an adverse supply shock , the bursting of an economic bubble , or a large-scale anthropogenic or natural disaster (e.g. a pandemic ). There is no official definition of a recession, according to the IMF . In the United States , a recession is defined as "a significant decline in economic activity spread across the market, lasting more than

440-506: A 1974 article by The New York Times , Commissioner of the Bureau of Labor Statistics Julius Shiskin suggested that a rough translation of the bureau's qualitative definition of a recession into a quantitative one that almost anyone can use might run like this: Over the years, some commentators dropped most of Shiskin's "recession-spotting" criteria for the simplistic rule-of-thumb of a decline in real GNI for two consecutive quarters. In

550-803: A M.S. as professors too (and rarely, some big universities who need part-time or temporary instructors, or temporary staff), but when the positions are scarce and the applicants are many, they might prefer Ph.D. holders instead. Skills that a chemist may need on the job include: Most chemists begin their lives in research laboratories . Many chemists continue working at universities. Other chemists may start companies, teach at high schools or colleges, take samples outside (as environmental chemists ), or work in medical examiner offices or police departments (as forensic chemists ). Some software that chemists may find themselves using include: Increasingly, chemists may also find themselves using artificial intelligence , such as for drug discovery . Chemistry typically

660-403: A Master of Science (M.S.) in chemistry or in a very related discipline may find chemist roles that allow them to enjoy more independence, leadership and responsibility earlier in their careers with less years of experience than those with a bachelor's degree as highest degree. Sometimes, M.S. chemists receive more complex tasks duties in comparison with the roles and positions found by chemists with

770-559: A Ph.D. more often than not. Chemists with a Ph.D. as the highest academic degree are found typically on the research-and-development department of an enterprise and can also hold university positions as professors. Professors for research universities or for big universities usually have a Ph.D., and some research-oriented institutions might require post-doctoral training. Some smaller colleges (including some smaller four-year colleges or smaller non-research universities for undergraduates) as well as community colleges usually hire chemists with

880-604: A bachelor's degree are most commonly involved in positions related to either research assistance (working under the guidance of senior chemists in a research-oriented activity), or, alternatively, they may work on distinct (chemistry-related) aspects of a business, organization or enterprise including aspects that involve quality control, quality assurance, manufacturing, production, formulation, inspection, method validation, visitation for troubleshooting of chemistry-related instruments, regulatory affairs , "on-demand" technical services, chemical analysis for non-research purposes (e.g., as

990-466: A bachelor's degree as their highest academic degree and with the same or close-to-same years of job experience. There are positions that are open only to those that at least have a degree related to chemistry at the master's level. Although good chemists without a Ph.D. degree but with relatively many years of experience may be allowed some applied research positions, the general rule is that Ph.D. chemists are preferred for research positions and are typically

1100-409: A balance sheet recession would be appropriate. However, Krugman argued that monetary policy could also affect savings behavior, as inflation or credible promises of future inflation (generating negative real interest rates) would encourage less savings. In other words, people would tend to spend more rather than save if they believe inflation is on the horizon. In more technical terms, Krugman argues that

1210-467: A chemical reaction is said to have occurred. A chemical reaction is therefore a concept related to the "reaction" of a substance when it comes in close contact with another, whether as a mixture or a solution ; exposure to some form of energy, or both. It results in some energy exchange between the constituents of the reaction as well as with the system environment, which may be designed vessels—often laboratory glassware . Chemical reactions can result in

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1320-470: A chemical transformation is the rearrangement of electrons in the chemical bonds between atoms. It can be symbolically depicted through a chemical equation , which usually involves atoms as subjects. The number of atoms on the left and the right in the equation for a chemical transformation is equal. (When the number of atoms on either side is unequal, the transformation is referred to as a nuclear reaction or radioactive decay .) The type of chemical reactions

1430-435: A combination of education, experience and personal achievements), the higher the responsibility given to that chemist and the more complicated the task might be. Chemistry, as a field, have so many applications that different tasks and objectives can be given to workers or scientists with these different levels of education or experience. The specific title of each job varies from position to position, depending on factors such as

1540-410: A complexity requiring an education with a chemistry degree, are commonly referred to as chemical technicians . Such technicians commonly do such work as simpler, routine analyses for quality control or in clinical laboratories , having an associate degree . A chemical technologist has more education or experience than a chemical technician but less than a chemist, often having a bachelor's degree in

1650-513: A comprehensive assessment of the depth and breadth of economic downturns, enabling policymakers to devise more effective strategies for economic stabilization and recovery. Recessions in the United Kingdom are generally defined as two consecutive quarters of negative economic growth, as measured by the seasonal adjusted quarter-on-quarter figures for real GDP . The Organisation for Economic Co-operation and Development (OECD) defines

1760-412: A dense core called the atomic nucleus surrounded by a space occupied by an electron cloud . The nucleus is made up of positively charged protons and uncharged neutrons (together called nucleons ), while the electron cloud consists of negatively charged electrons which orbit the nucleus. In a neutral atom, the negatively charged electrons balance out the positive charge of the protons. The nucleus

1870-409: A different field of science with also an associate degree in chemistry (or many credits related to chemistry) or having the same education as a chemical technician but more experience. There are also degrees specific to become a chemical technologist, which are somewhat distinct from those required when a student is interested in becoming a professional chemist. A Chemical technologist is more involved in

1980-535: A directed beam in a vacuum in a mass spectrometer . Charged polyatomic collections residing in solids (for example, common sulfate or nitrate ions) are generally not considered "molecules" in chemistry. Some molecules contain one or more unpaired electrons, creating radicals . Most radicals are comparatively reactive, but some, such as nitric oxide (NO) can be stable. The "inert" or noble gas elements ( helium , neon , argon , krypton , xenon and radon ) are composed of lone atoms as their smallest discrete unit, but

2090-588: A few months, normally visible in real GDP , real income, employment, industrial production, and wholesale-retail sales." The European Union has adopted a similar definition. In the United Kingdom and Canada , a recession is defined as negative economic growth for two consecutive quarters. Governments usually respond to recessions by adopting expansionary macroeconomic policies , such as increasing money supply and decreasing interest rates or increasing government spending and decreasing taxation . In

2200-801: A fundamental level. For example, chemistry explains aspects of plant growth ( botany ), the formation of igneous rocks ( geology ), how atmospheric ozone is formed and how environmental pollutants are degraded ( ecology ), the properties of the soil on the Moon ( cosmochemistry ), how medications work ( pharmacology ), and how to collect DNA evidence at a crime scene ( forensics ). Chemistry has existed under various names since ancient times. It has evolved, and now chemistry encompasses various areas of specialisation, or subdisciplines, that continue to increase in number and interrelate to create further interdisciplinary fields of study. The applications of various fields of chemistry are used frequently for economic purposes in

2310-463: A key demand component of GDP, fell enormously (22% of GDP) between 1990 and its peak decline in 2003. Japanese firms overall became net savers after 1998, as opposed to borrowers. Koo argues that it was massive fiscal stimulus (borrowing and spending by the government) that offset this decline and enabled Japan to maintain its level of GDP. In his view, this avoided a U.S. type Great Depression , in which U.S. GDP fell by 46%. He argued that monetary policy

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2420-507: A legal request, for testing purposes, or for government or non-profit agencies); chemists may also work in environmental evaluation and assessment. Other jobs or roles may include sales and marketing of chemical products and chemistry-related instruments or technical writing. The more experience obtained, the more independence and leadership or management roles these chemists may perform in those organizations. Some chemists with relatively higher experience might change jobs or job position to become

2530-502: A liquidity trap is expanding the money supply via quantitative easing or other techniques in which money is effectively printed to purchase assets, thereby creating inflationary expectations that cause savers to begin spending again. Government stimulus spending and mercantilist policies to stimulate exports and reduce imports are other techniques to stimulate demand. He estimated in March 2010 that developed countries representing 70% of

2640-467: A manager of a chemistry-related enterprise, a supervisor, an entrepreneur or a chemistry consultant. Other chemists choose to combine their education and experience as a chemist with a distinct credential to provide different services (e.g., forensic chemists, chemistry-related software development, patent law specialists, environmental law firm staff, scientific news reporting staff, engineering design staff, etc.). In comparison, chemists who have obtained

2750-411: A number of steps, each of which may have a different speed. Many reaction intermediates with variable stability can thus be envisaged during the course of a reaction. Reaction mechanisms are proposed to explain the kinetics and the relative product mix of a reaction. Many physical chemists specialize in exploring and proposing the mechanisms of various chemical reactions. Several empirical rules, like

2860-424: A particular substance per volume of solution , and is commonly reported in mol/ dm . In addition to the specific chemical properties that distinguish different chemical classifications, chemicals can exist in several phases. For the most part, the chemical classifications are independent of these bulk phase classifications; however, some more exotic phases are incompatible with certain chemical properties. A phase

2970-471: A positive hydrogen ion to another substance in a chemical reaction; by extension, a base is the substance which receives that hydrogen ion. Recession Heterodox In economics , a recession is a business cycle contraction that occurs when there is a period of broad decline in economic activity. Recessions generally occur when there is a widespread drop in spending (an adverse demand shock ). This may be triggered by various events, such as

3080-405: A pure chemical substance that has its unique set of chemical properties, that is, its potential to undergo a certain set of chemical reactions with other substances. However, this definition only works well for substances that are composed of molecules, which is not true of many substances (see below). Molecules are typically a set of atoms bound together by covalent bonds , such that the structure

3190-833: A recession as a period of at least two years during which the cumulative output gap reaches at least 2% of GDP, and the output gap is at least 1% for at least one year. Recession can be defined as decline of GDP per capita instead of decline of total GDP. A recession encompasses multiple attributes that often occur simultaneously and encompasses declines in component measures of economic activity, such as GDP, including consumption, investment, government spending, and net export activity. These summary measures are indicative of underlying drivers such as employment levels and skills, household savings rates, corporate investment decisions, interest rates, demographics, and government policies (Smith, 2018; Johnson & Thompson, 2020). By examining these factors comprehensively, economists gain insights into

3300-493: A recession including the availability heuristic , the money illusion , and normalcy bias . Excessive levels of indebtedness or the bursting of a real estate or financial asset price bubble can cause what is called a "balance sheet recession". This occurs when large numbers of consumers or corporations pay down debt (i.e., save) rather than spend or invest, which slows the economy. The term balance sheet derives from an accounting identity that holds that assets must always equal

3410-427: A recession. Economist Hyman Minsky also described a "paradox of deleveraging" as financial institutions that have too much leverage (debt relative to equity) cannot all de-leverage simultaneously without significant declines in the value of their assets. In April 2009, U.S. Federal Reserve Vice Chair Janet Yellen discussed these paradoxes: "Once this massive credit crunch hit, it didn't take long before we were in

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3520-619: A recession. The recession, in turn, deepened the credit crunch as demand and employment fell, and credit losses of financial institutions surged. Indeed, we have been in the grips of precisely this adverse feedback loop for more than a year. A process of balance sheet deleveraging has spread to nearly every corner of the economy. Consumers are pulling back on purchases, especially durable goods, to build their savings. Businesses are cancelling planned investments and laying off workers to preserve cash. And financial institutions are shrinking assets to bolster capital and improve their chances of weathering

3630-459: A reliable recession predictor. The curve began re-steepening toward positive territory in June 2024, as it had at other points during that inversion; in every previous inversion they examined; Deutsche Bank analysts found the curve had re-steepened before a recession began. The following variables and indicators are used by economists, like e.g. Paul Krugman or Joseph Stiglitz , to try to predict

3740-415: A self-reinforcing downward cycle, bringing about or worsening a recession. Consumer confidence is one measure used to evaluate economic sentiment. The term animal spirits has been used to describe the psychological factors underlying economic activity. Keynes, in his The General Theory of Employment, Interest and Money , was the first economist to claim that such emotional mindsets significantly affect

3850-609: A substance may undergo and the energy changes that may accompany it are constrained by certain basic rules, known as chemical laws . Energy and entropy considerations are invariably important in almost all chemical studies. Chemical substances are classified in terms of their structure , phase, as well as their chemical compositions . They can be analyzed using the tools of chemical analysis , e.g. spectroscopy and chromatography . Scientists engaged in chemical research are known as chemists . Most chemists specialize in one or more sub-disciplines. Several concepts are essential for

3960-414: Is a pure substance which is composed of a single type of atom, characterized by its particular number of protons in the nuclei of its atoms, known as the atomic number and represented by the symbol Z . The mass number is the sum of the number of protons and neutrons in a nucleus. Although all the nuclei of all atoms belonging to one element will have the same atomic number, they may not necessarily have

4070-409: Is a set of states of a chemical system that have similar bulk structural properties, over a range of conditions, such as pressure or temperature . Physical properties, such as density and refractive index tend to fall within values characteristic of the phase. The phase of matter is defined by the phase transition , which is when energy put into or taken out of the system goes into rearranging

4180-586: Is a very useful means for predicting the feasibility of a reaction and determining the state of equilibrium of a chemical reaction, in chemical thermodynamics . A reaction is feasible only if the total change in the Gibbs free energy is negative, Δ G ≤ 0 {\displaystyle \Delta G\leq 0\,} ; if it is equal to zero the chemical reaction is said to be at equilibrium . There exist only limited possible states of energy for electrons, atoms and molecules. These are determined by

4290-642: Is also known as " the central science ", thus chemists ought to have a well-rounded knowledge about science. At the Master's level and higher, students tend to specialize in a particular field. Fields of specialization include biochemistry , nuclear chemistry , organic chemistry , inorganic chemistry , polymer chemistry , analytical chemistry , physical chemistry , theoretical chemistry , quantum chemistry , environmental chemistry , and thermochemistry . Postdoctoral experience may be required for certain positions. Workers whose work involves chemistry, but not at

4400-422: Is also possible to define analogs in two-dimensional systems, which has received attention for its relevance to systems in biology . Atoms sticking together in molecules or crystals are said to be bonded with one another. A chemical bond may be visualized as the multipole balance between the positive charges in the nuclei and the negative charges oscillating about them. More than simple attraction and repulsion,

4510-439: Is also used to identify the composition of remote objects – like stars and distant galaxies – by analyzing their radiation spectra. The term chemical energy is often used to indicate the potential of a chemical substance to undergo a transformation through a chemical reaction or to transform other chemical substances. When a chemical substance is transformed as a result of its interaction with another substance or with energy,

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4620-464: Is called a mixture. Examples of mixtures are air and alloys . The mole is a unit of measurement that denotes an amount of substance (also called chemical amount). One mole is defined to contain exactly 6.022 140 76 × 10 particles ( atoms , molecules , ions , or electrons ), where the number of particles per mole is known as the Avogadro constant . Molar concentration is the amount of

4730-523: Is composed of gaseous matter that has been completely ionized, usually through high temperature. A substance can often be classified as an acid or a base . There are several different theories which explain acid–base behavior. The simplest is Arrhenius theory , which states that acid is a substance that produces hydronium ions when it is dissolved in water, and a base is one that produces hydroxide ions when dissolved in water. According to Brønsted–Lowry acid–base theory , acids are substances that donate

4840-472: Is dense; the mass of a nucleon is approximately 1,836 times that of an electron, yet the radius of an atom is about 10,000 times that of its nucleus. The atom is also the smallest entity that can be envisaged to retain the chemical properties of the element, such as electronegativity , ionization potential , preferred oxidation state (s), coordination number , and preferred types of bonds to form (e.g., metallic , ionic , covalent ). A chemical element

4950-1092: Is divided into several major sub-disciplines. There are also several main cross-disciplinary and more specialized fields of chemistry. There is a great deal of overlap between different branches of chemistry, as well as with other scientific fields such as biology, medicine, physics, radiology , and several engineering disciplines. All the above major areas of chemistry employ chemists. Other fields where chemical degrees are useful include astrochemistry (and cosmochemistry ), atmospheric chemistry , chemical engineering , chemo-informatics , electrochemistry , environmental science , forensic science , geochemistry , green chemistry , history of chemistry , materials science , medical science , molecular biology , molecular genetics , nanotechnology , nuclear chemistry , oenology , organometallic chemistry , petrochemistry , pharmacology , photochemistry , phytochemistry , polymer chemistry , supramolecular chemistry and surface chemistry . Chemists may belong to professional societies specifically for professionals and researchers within

5060-464: Is electrically neutral and all valence electrons are paired with other electrons either in bonds or in lone pairs . Thus, molecules exist as electrically neutral units, unlike ions. When this rule is broken, giving the "molecule" a charge, the result is sometimes named a molecular ion or a polyatomic ion. However, the discrete and separate nature of the molecular concept usually requires that molecular ions be present only in well-separated form, such as

5170-537: Is more easily transferred between substances relative to light or other forms of electronic energy. For example, ultraviolet electromagnetic radiation is not transferred with as much efficacy from one substance to another as thermal or electrical energy. The existence of characteristic energy levels for different chemical substances is useful for their identification by the analysis of spectral lines . Different kinds of spectra are often used in chemical spectroscopy , e.g. IR , microwave , NMR , ESR , etc. Spectroscopy

5280-522: Is not an official designation" and that instead, "The designation of a recession is the province of a committee of experts at the National Bureau of Economic Research". The European Union, akin to the NBER's methodology, has embraced a definition of recession that integrates GDP alongside a spectrum of macroeconomic indicators, including employment and various other metrics. This approach allows for

5390-429: Is often related to the work of chemical engineers , who are primarily concerned with the proper design, construction and evaluation of the most cost-effective large-scale chemical plants and work closely with industrial chemists on the development of new processes and methods for the commercial-scale manufacture of chemicals and related products. The roots of chemistry can be traced to the phenomenon of burning . Fire

5500-627: Is referred to as an economic depression , although some argue that their causes and cures can be different. As an informal shorthand, economists sometimes refer to different recession shapes , such as V-shaped , U-shaped , L-shaped and W-shaped recessions. The type and shape of recessions are distinctive. In the US, v-shaped, or short-and-sharp contractions followed by rapid and sustained recovery, occurred in 1954 and 1990–1991; U-shaped (prolonged slump) in 1974–1975, and W-shaped, or double-dip recessions in 1949 and 1980–1982. Japan's 1993–1994 recession

5610-468: Is the crystal structure , or arrangement, of the atoms. Another phase commonly encountered in the study of chemistry is the aqueous phase, which is the state of substances dissolved in aqueous solution (that is, in water). Less familiar phases include plasmas , Bose–Einstein condensates and fermionic condensates and the paramagnetic and ferromagnetic phases of magnetic materials. While most familiar phases deal with three-dimensional systems, it

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5720-458: Is the quantum mechanical model . Traditional chemistry starts with the study of elementary particles , atoms , molecules , substances , metals , crystals and other aggregates of matter . Matter can be studied in solid, liquid, gas and plasma states , in isolation or in combination. The interactions, reactions and transformations that are studied in chemistry are usually the result of interactions between atoms, leading to rearrangements of

5830-507: Is the probability of a molecule to have energy greater than or equal to E at the given temperature T. This exponential dependence of a reaction rate on temperature is known as the Arrhenius equation . The activation energy necessary for a chemical reaction to occur can be in the form of heat, light, electricity or mechanical force in the form of ultrasound . A related concept free energy , which also incorporates entropy considerations,

5940-526: Is useful in identifying periodic trends . A compound is a pure chemical substance composed of more than one element. The properties of a compound bear little similarity to those of its elements. The standard nomenclature of compounds is set by the International Union of Pure and Applied Chemistry (IUPAC). Organic compounds are named according to the organic nomenclature system. The names for inorganic compounds are created according to

6050-541: The (inverted) yield curve appear to be more useful to predict a recession ahead of time than other variables, no single variable has proven to be an always reliable predictor whether recessions will actually (soon) appear, let alone predicting their sharpness and severity in terms of duration. The longest and deepest Treasury yield curve inversion in history began in July 2022, as the Federal Reserve sharply increased

6160-647: The Neo-Latin noun chimista , an abbreviation of alchimista ( alchemist ). Alchemists discovered many chemical processes that led to the development of modern chemistry. Chemistry as we know it today, was invented by Antoine Lavoisier with his law of conservation of mass in 1783. The discoveries of the chemical elements has a long history culminating in the creation of the periodic table by Dmitri Mendeleev . The Nobel Prize in Chemistry created in 1901 gives an excellent overview of chemical discovery since

6270-682: The United States , the Business Cycle Dating Committee of the National Bureau of Economic Research (NBER) is generally seen as the authority for dating US recessions. The NBER, a private economic research organization, defines an economic recession as: "a significant decline in economic activity spread across the economy, lasting more than a few months, normally visible in real GDP , real income , employment, industrial production , and wholesale - retail sales ". The NBER also explains that: "a recession begins when

6380-509: The Woodward–Hoffmann rules often come in handy while proposing a mechanism for a chemical reaction. According to the IUPAC gold book, a chemical reaction is "a process that results in the interconversion of chemical species." Accordingly, a chemical reaction may be an elementary reaction or a stepwise reaction . An additional caveat is made, in that this definition includes cases where

6490-455: The chemical bonds which hold atoms together. Such behaviors are studied in a chemistry laboratory . The chemistry laboratory stereotypically uses various forms of laboratory glassware . However glassware is not central to chemistry, and a great deal of experimental (as well as applied/industrial) chemistry is done without it. A chemical reaction is a transformation of some substances into one or more different substances. The basis of such

6600-493: The chemical industry . The word chemistry comes from a modification during the Renaissance of the word alchemy , which referred to an earlier set of practices that encompassed elements of chemistry, metallurgy , philosophy , astrology , astronomy , mysticism , and medicine . Alchemy is often associated with the quest to turn lead or other base metals into gold, though alchemists were also interested in many of

6710-469: The duet rule , and in this way they are reaching the electron configuration of the noble gas helium , which has two electrons in its outer shell. Similarly, theories from classical physics can be used to predict many ionic structures. With more complicated compounds, such as metal complexes , valence bond theory is less applicable and alternative approaches, such as the molecular orbital theory, are generally used. See diagram on electronic orbitals. In

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6820-450: The fed funds rate to combat the 2021–2023 inflation surge . Despite widespread predictions by economists and market analysts of an imminent recession, none had materialized by July 2024, economic growth remained steady, and a Reuters survey of economists that month found they expected the economy to continue growing for the next two years. An earlier survey of bond market strategists found a majority no longer believed an inverted curve to be

6930-510: The inorganic nomenclature system. When a compound has more than one component, then they are divided into two classes, the electropositive and the electronegative components. In addition the Chemical Abstracts Service has devised a method to index chemical substances. In this scheme each chemical substance is identifiable by a number known as its CAS registry number . A molecule is the smallest indivisible portion of

7040-500: The interconversion of conformers is experimentally observable. Such detectable chemical reactions normally involve sets of molecular entities as indicated by this definition, but it is often conceptually convenient to use the term also for changes involving single molecular entities (i.e. 'microscopic chemical events'). An ion is a charged species, an atom or a molecule, that has lost or gained one or more electrons. When an atom loses an electron and thus has more protons than electrons,

7150-529: The intermolecular forces of a substance are such that the energy of the surroundings is not sufficient to overcome them, it occurs in a more ordered phase like liquid or solid as is the case with water (H 2 O); a liquid at room temperature because its molecules are bound by hydrogen bonds . Whereas hydrogen sulfide (H 2 S) is a gas at room temperature and standard pressure, as its molecules are bound by weaker dipole–dipole interactions . The transfer of energy from one chemical substance to another depends on

7260-608: The private sector as it pays down its debt. For example, economist Richard Koo wrote that Japan's "Great Recession" that began in 1990 was a "balance sheet recession". It was triggered by a collapse in land and stock prices, which caused Japanese firms to have negative equity , meaning their assets were worth less than their liabilities. Despite zero interest rates and expansion of the money supply to encourage borrowing, Japanese corporations in aggregate opted to pay down their debts from their own business earnings rather than borrow to invest as firms typically do. Corporate investment,

7370-438: The size of energy quanta emitted from one substance. However, heat energy is often transferred more easily from almost any substance to another because the phonons responsible for vibrational and rotational energy levels in a substance have much less energy than photons invoked for the electronic energy transfer. Thus, because vibrational and rotational energy levels are more closely spaced than electronic energy levels, heat

7480-653: The 2015 Hague Ethical Guidelines . The highest honor awarded to chemists is the Nobel Prize in Chemistry , awarded since 1901, by the Royal Swedish Academy of Sciences . Chemistry#Subdisciplines Chemistry is the scientific study of the properties and behavior of matter . It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms , molecules and ions : their composition, structure, properties, behavior and

7590-515: The Valence Shell Electron Pair Repulsion model ( VSEPR ), and the concept of oxidation number can be used to explain molecular structure and composition. An ionic bond is formed when a metal loses one or more of its electrons, becoming a positively charged cation, and the electrons are then gained by the non-metal atom, becoming a negatively charged anion. The two oppositely charged ions attract one another, and

7700-494: The atom is a positively charged ion or cation . When an atom gains an electron and thus has more electrons than protons, the atom is a negatively charged ion or anion . Cations and anions can form a crystalline lattice of neutral salts , such as the Na and Cl ions forming sodium chloride , or NaCl. Examples of polyatomic ions that do not split up during acid–base reactions are hydroxide (OH ) and phosphate (PO 4 ). Plasma

7810-411: The changes they undergo during reactions with other substances . Chemistry also addresses the nature of chemical bonds in chemical compounds . In the scope of its subject, chemistry occupies an intermediate position between physics and biology . It is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at

7920-480: The complex dynamics that contribute to economic downturns and can formulate effective strategies for mitigating their impact (Anderson, 2019; Patel, 2017). Economist Richard C. Koo wrote that under ideal conditions, a country's economy should have the household sector as net savers and the corporate sector as net borrowers, with the government budget nearly balanced and net exports near zero. A severe (GDP down by 10%) or prolonged (three or four years) recession

8030-412: The context of chemistry, energy is an attribute of a substance as a consequence of its atomic , molecular or aggregate structure . Since a chemical transformation is accompanied by a change in one or more of these kinds of structures, it is invariably accompanied by an increase or decrease of energy of the substances involved. Some energy is transferred between the surroundings and the reactants of

8140-410: The current storm. Once again, Minsky understood this dynamic. He spoke of the paradox of deleveraging, in which precautions that may be smart for individuals and firms—and indeed essential to return the economy to a normal state—nevertheless magnify the distress of the economy as a whole." There are many reasons why recessions happen. One overall reason can be lack of demand due to sharp developments in

8250-510: The decline in property values experienced during the subprime mortgage crisis. Further, reduced consumption due to higher household leverage can account for a significant decline in employment levels. Policies that help reduce mortgage debt or household leverage could therefore have stimulative effects (Smith & Johnson, 2012). A liquidity trap is a Keynesian theory that a situation can develop in which interest rates reach near zero ( zero interest-rate policy ) yet do not effectively stimulate

8360-486: The economy reaches a peak of activity and ends when the economy reaches its through." The NBER is considered the official arbiter of recession start and end dates for the United States. The Bureau of Economic Analysis , an independent federal agency that provides official macroeconomic and industry statistics, says "the often-cited identification of a recession with two consecutive quarters of negative GDP growth

8470-442: The economy. Economist Robert J. Shiller wrote that the term "refers also to the sense of trust we have in each other, our sense of fairness in economic dealings, and our sense of the extent of corruption and bad faith. When animal spirits are on ebb, consumers do not want to spend and businesses do not want to make capital expenditures or hire people." Behavioral economics has also explained many psychological biases that may trigger

8580-475: The economy. In theory, near-zero interest rates should encourage firms and consumers to borrow and spend. However, if too many individuals or corporations focus on saving or paying down debt rather than spending, lower interest rates have less effect on investment and consumption behavior; increasing the money supply is like " pushing on a string ". Economist Paul Krugman described the U.S. 2009 recession and Japan's lost decade as liquidity traps. One remedy to

8690-429: The energies and distributions characterize the availability of an electron to bond to another atom. The chemical bond can be a covalent bond , an ionic bond , a hydrogen bond or just because of Van der Waals force . Each of these kinds of bonds is ascribed to some potential. These potentials create the interactions which hold atoms together in molecules or crystals . In many simple compounds, valence bond theory ,

8800-420: The exact roles of these chemistry-related workers as standard for that given level of education. Because of these factors affecting exact job titles with distinct responsibilities, some chemists might begin doing technician tasks while other chemists might begin doing more complicated tasks than those of a technician, such as tasks that also involve formal applied research, management, or supervision included within

8910-850: The field of chemistry, such as the Royal Society of Chemistry in the United Kingdom, the American Chemical Society (ACS) in the United States, or the Institution of Chemists in India. The "Global Chemists' Code of Ethics" suggests several ethical principles that all chemists should follow: This code of ethics was codified in a 2016 conference held in Kuala Lumpur, Malaysia , run by the American Chemical Society. The points listed are inspired by

9020-558: The following are considered possible predictors: Manufacturing: Industrial Production: Chemical Activity: Transportation: Corporate Profits: Employment: Personal Income: Household Savings and Consumer Debt: Retail Sales, Consumer Confidence and Consumer Expenditures: Housing and non-residential construction: Credit Markets: Business Expectations: Margin of stock market traders: Asset Prices: Gross Domestic Product: Unorthodox Recession Indicators: Overview of recession indicators: Sahm Recession Indicator signals

9130-449: The following categories: Economic factors: Financial factors: External shocks Summary: Why recessions happen is a complex phenomena often resulting from a interplay of various factors. While these factors can individually contribute to a recession, the cumulative impact of several occurring simultaneously can significantly amplify the negative effect on the economy. Recessions are very challenging to predict. While some variables like

9240-444: The formation or dissociation of molecules, that is, molecules breaking apart to form two or more molecules or rearrangement of atoms within or across molecules. Chemical reactions usually involve the making or breaking of chemical bonds. Oxidation, reduction , dissociation , acid–base neutralization and molecular rearrangement are some examples of common chemical reactions. A chemical reaction can be symbolically depicted through

9350-445: The ionic bond is the electrostatic force of attraction between them. For example, sodium (Na), a metal, loses one electron to become an Na cation while chlorine (Cl), a non-metal, gains this electron to become Cl . The ions are held together due to electrostatic attraction, and that compound sodium chloride (NaCl), or common table salt, is formed. In a covalent bond, one or more pairs of valence electrons are shared by two atoms:

9460-419: The kind of industry, the routine level of the task, the current needs of a particular enterprise, the size of the enterprise or hiring firm, the philosophy and management principles of the hiring firm, the visibility of the competency and individual achievements of the one seeking employment, economic factors such as recession or economic depression , among other factors, so this makes it difficult to categorize

9570-473: The main characteristics of a molecule is its geometry often called its structure . While the structure of diatomic, triatomic or tetra-atomic molecules may be trivial, (linear, angular pyramidal etc.) the structure of polyatomic molecules, that are constituted of more than six atoms (of several elements) can be crucial for its chemical nature. A chemical substance is a kind of matter with a definite composition and set of properties . A collection of substances

9680-424: The management and operation of the equipment and instrumentation necessary to perform chemical analyzes than a chemical technician. They are part of the team of a chemical laboratory in which the quality of the raw material, intermediate products and finished products is analyzed. They also perform functions in the areas of environmental quality control and the operational phase of a chemical plant. In addition to all

9790-419: The other isolated chemical elements consist of either molecules or networks of atoms bonded to each other in some way. Identifiable molecules compose familiar substances such as water, air, and many organic compounds like alcohol, sugar, gasoline, and the various pharmaceuticals . However, not all substances or chemical compounds consist of discrete molecules, and indeed most of the solid substances that make up

9900-507: The possibility of a recession: Except for the above, there are no known completely reliable predictors. Analysis by Prakash Loungani of the International Monetary Fund found that only two of the sixty recessions around the world during the 1990s had been predicted by a consensus of economists one year earlier, while there were zero consensus predictions one year earlier for the 49 recessions during 2009. However,

10010-450: The preferred choice for the highest administrative positions on big enterprises involved in chemistry-related duties. Some positions, especially research oriented, will only allow those chemists who are Ph.D. holders. Jobs that involve intensive research and actively seek to lead the discovery of completely new chemical compounds under specifically assigned monetary funds and resources or jobs that seek to develop new scientific theories require

10120-419: The prices of the inputs used in producing goods and services. Another main reason can be problems e.g. in financial markets. Because recessions have many likely explanations, it is demanding to predict them. Some variables might at first glance be the causes of recessions, but they could also be the results of a recession, which means they are endogenous to recessions. One can summarize the causes of recessions in

10230-484: The private sector savings curve is elastic even during a balance sheet recession (responsive to changes in real interest rates), disagreeing with Koo's view that it is inelastic (non-responsive to changes in real interest rates). A July 2012 survey of balance sheet recession research reported that consumer demand and employment are affected by household leverage levels. Both durable and non-durable goods consumption declined as households moved from low to high leverage with

10340-631: The questions of modern chemistry. The modern word alchemy in turn is derived from the Arabic word al-kīmīā ( الكیمیاء ). This may have Egyptian origins since al-kīmīā is derived from the Ancient Greek χημία , which is in turn derived from the word Kemet , which is the ancient name of Egypt in the Egyptian language. Alternately, al-kīmīā may derive from χημεία 'cast together'. The current model of atomic structure

10450-478: The reaction absorbs heat from the surroundings. Chemical reactions are invariably not possible unless the reactants surmount an energy barrier known as the activation energy . The speed of a chemical reaction (at given temperature T) is related to the activation energy E, by the Boltzmann's population factor e − E / k T {\displaystyle e^{-E/kT}} – that

10560-433: The reaction in the form of heat or light ; thus the products of a reaction may have more or less energy than the reactants. A reaction is said to be exergonic if the final state is lower on the energy scale than the initial state; in the case of endergonic reactions the situation is the reverse. A reaction is said to be exothermic if the reaction releases heat to the surroundings; in the case of endothermic reactions ,

10670-414: The responsibilities of that same job title. The level of supervision given to that chemist also varies in a similar manner, with factors similar to those that affect the tasks demanded for a particular chemist It is important that those interested in a Chemistry degree understand the variety of roles available to them (on average), which vary depending on education and job experience. Those Chemists who hold

10780-544: The resulting electrically neutral group of bonded atoms is termed a molecule . Atoms will share valence electrons in such a way as to create a noble gas electron configuration (eight electrons in their outermost shell) for each atom. Atoms that tend to combine in such a way that they each have eight electrons in their valence shell are said to follow the octet rule . However, some elements like hydrogen and lithium need only two electrons in their outermost shell to attain this stable configuration; these atoms are said to follow

10890-403: The rules of quantum mechanics , which require quantization of energy of a bound system. The atoms/molecules in a higher energy state are said to be excited. The molecules/atoms of substance in an excited energy state are often much more reactive; that is, more amenable to chemical reactions. The phase of a substance is invariably determined by its energy and the energy of its surroundings. When

11000-474: The same mass number; atoms of an element which have different mass numbers are known as isotopes . For example, all atoms with 6 protons in their nuclei are atoms of the chemical element carbon , but atoms of carbon may have mass numbers of 12 or 13. The standard presentation of the chemical elements is in the periodic table , which orders elements by atomic number. The periodic table is arranged in groups , or columns, and periods , or rows. The periodic table

11110-645: The solid crust, mantle, and core of the Earth are chemical compounds without molecules. These other types of substances, such as ionic compounds and network solids , are organized in such a way as to lack the existence of identifiable molecules per se . Instead, these substances are discussed in terms of formula units or unit cells as the smallest repeating structure within the substance. Examples of such substances are mineral salts (such as table salt ), solids like carbon and diamond, metals, and familiar silica and silicate minerals such as quartz and granite. One of

11220-570: The start of the 20th century. At the Washington Academy of Sciences during World War I , it was said that the side with the best chemists would win the war. Jobs for chemists generally require at least a bachelor's degree in chemistry, which takes four years. However, many positions, especially those in research, require a Master of Science or a Doctor of Philosophy (PhD.). Most undergraduate programs emphasize mathematics and physics as well as chemistry, partly because chemistry

11330-695: The structure of the system, instead of changing the bulk conditions. Sometimes the distinction between phases can be continuous instead of having a discrete boundary' in this case the matter is considered to be in a supercritical state. When three states meet based on the conditions, it is known as a triple point and since this is invariant, it is a convenient way to define a set of conditions. The most familiar examples of phases are solids , liquids , and gases . Many substances exhibit multiple solid phases. For example, there are three phases of solid iron (alpha, gamma, and delta) that vary based on temperature and pressure. A principal difference between solid phases

11440-421: The study of chemistry; some of them are: In chemistry, matter is defined as anything that has rest mass and volume (it takes up space) and is made up of particles . The particles that make up matter have rest mass as well – not all particles have rest mass, such as the photon . Matter can be a pure chemical substance or a mixture of substances. The atom is the basic unit of chemistry. It consists of

11550-556: The sum of liabilities plus equity. If asset prices fall below the value of the debt incurred to purchase them, then the equity must be negative, meaning the consumer or corporation is insolvent. Economist Paul Krugman wrote in 2014 that "the best working hypothesis seems to be that the financial crisis was only one manifestation of a broader problem of excessive debt—that it was a so-called "balance sheet recession". In Krugman's view, such crises require debt reduction strategies combined with higher government spending to offset declines from

11660-412: The training usually given to chemical technologists in their respective degree (or one given via an associate degree), a chemist is also trained to understand more details related to chemical phenomena so that the chemist can be capable of more planning on the steps to achieve a distinct goal via a chemistry-related endeavor. The higher the competency level achieved in the field of chemistry (as assessed via

11770-421: The world's GDP were caught in a liquidity trap. Behavior that may be optimal for an individual (e.g., saving more during adverse economic conditions) can be detrimental if too many individuals pursue the same behavior, as ultimately, one person's consumption is another person's income. Too many consumers attempting to save (or pay down debt) simultaneously is called the paradox of thrift and can cause or deepen

11880-489: Was U-shaped and its 8-out-of-9 quarters of contraction in 1997–1999 can be described as L-shaped. Korea , Hong Kong and South-east Asia experienced U-shaped recessions in 1997–1998, although Thailand 's eight consecutive quarters of decline should be termed L-shaped. Recessions have psychological and confidence aspects. For example, if companies expect economic activity to slow, they may reduce employment levels and save money rather than invest. Such expectations can create

11990-407: Was a mystical force that transformed one substance into another and thus was of primary interest to mankind. It was fire that led to the discovery of iron and glasses . After gold was discovered and became a precious metal, many people were interested to find a method that could convert other substances into gold. This led to the protoscience called alchemy . The word chemist is derived from

12100-438: Was ineffective because there was limited demand for funds while firms paid down their liabilities. In a balance sheet recession, GDP declines by the amount of debt repayment and un-borrowed individual savings, leaving government stimulus spending as the primary remedy. Krugman discussed the balance sheet recession concept in 2010, agreeing with Koo's situation assessment and view that sustained deficit spending when faced with

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