103-738: Afon Mynach ( Welsh pronunciation: [ˈmənaχ] ; also known as the River Mynach ) is a river in Ceredigion , Wales . Its source is at the meeting of two smaller rivers, the Nant Rhuddnant and the Afon Myherin . Both of these streams have their sources in lakes high in the Cambrian Mountains : The Afon Mynach is notable for the famous Mynach Falls in the village of Devil's Bridge (Pontarfynach), where
206-417: A heavy metal that is denser than most common materials. Lead is soft and malleable , and also has a relatively low melting point . When freshly cut, lead is a shiny gray with a hint of blue. It tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements. Lead
309-549: A collection of oral history interviews with people from Ceredigion during the 1960s and 1970s. The recordings were archived, digitised, catalogued and made available during the Unlocking Our Sound Heritage project at the National Library of Wales . Lead Lead (pronounced "led") is a chemical element ; it has symbol Pb (from Latin plumbum ) and atomic number 82. It is
412-543: A decline of 4,492 since the 2011 census . After Aberystwyth (15,935), the largest towns are Cardigan (4,184) and Lampeter (2,970). Ceredigion is considered a centre of Welsh culture and 45.3% of the population could speak the Welsh language at the 2021 census. To the west, Ceredigion has 50 miles (80 km) of coastline on Cardigan Bay , which is traversed by the Ceredigion Coast Path . Its hinterland
515-433: A density of 11.34 g/cm , which is greater than that of common metals such as iron (7.87 g/cm ), copper (8.93 g/cm ), and zinc (7.14 g/cm ). This density is the origin of the idiom to go over like a lead balloon . Some rarer metals are denser: tungsten and gold are both at 19.3 g/cm , and osmium —the densest metal known—has a density of 22.59 g/cm , almost twice that of lead. Lead
618-492: A few radioactive isotopes. One of them is lead-210; although it has a half-life of only 22.2 years, small quantities occur in nature because lead-210 is produced by a long decay series that starts with uranium-238 (that has been present for billions of years on Earth). Lead-211, −212, and −214 are present in the decay chains of uranium-235, thorium-232, and uranium-238, respectively, so traces of all three of these lead isotopes are found naturally. Minute traces of lead-209 arise from
721-558: A neutron and become thallium-204; this undergoes beta decay to give stable lead-204; on capturing another neutron, it becomes lead-205, which has a half-life of around 17 million years. Further captures result in lead-206, lead-207, and lead-208. On capturing another neutron, lead-208 becomes lead-209, which quickly decays into bismuth-209. On capturing another neutron, bismuth-209 becomes bismuth-210, and this beta decays to polonium-210, which alpha decays to lead-206. The cycle hence ends at lead-206, lead-207, lead-208, and bismuth-209. In
824-589: A permanent presence of bottlenose dolphins . Another member of the fauna is the red kite ; these may be seen in various localities in the county, but at the Red Kite Feeding Centre near Tregaron, they are fed each day, and large numbers congregate along with hungry crows and other birds. Between 1991 and 2003 Ceredigion had the largest population growth of any county in Wales, with a 19.5% increase. Tourism and agriculture, chiefly hill farming, are
927-466: A polyhedral vertex and contributes two electrons to each covalent bond along an edge from their sp hybrid orbitals, the other two being an external lone pair . They may be made in liquid ammonia via the reduction of lead by sodium . Lead can form multiply-bonded chains , a property it shares with its lighter homologs in the carbon group. Its capacity to do so is much less because the Pb–Pb bond energy
1030-746: A series of rapids near Llandysul where canoeing, kayaking and white water rafting take place. The county's main football team, Aberystwyth Town in the Cymru Premier , play their home matches at Park Avenue Stadium . Cardigan Town Football Club, also known as the "Magpies", play in Division 1 of the Ceredigion League. The Cambrian Line provides main line railway services between Aberystwyth , Shrewsbury and Birmingham , where passengers can join services for London and elsewhere. Passengers can change at Dovey Junction for trains along
1133-437: A significant partial positive charge on lead. The result is a stronger contraction of the lead 6s orbital than is the case for the 6p orbital, making it rather inert in ionic compounds. The inert pair effect is less applicable to compounds in which lead forms covalent bonds with elements of similar electronegativity, such as carbon in organolead compounds. In these, the 6s and 6p orbitals remain similarly sized and sp hybridization
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#17327756678661236-438: A single decay chain). In total, 43 lead isotopes have been synthesized, with mass numbers 178–220. Lead-205 is the most stable radioisotope, with a half-life of around 1.70 × 10 years. The second-most stable is lead-202, which has a half-life of about 52,500 years, longer than any of the natural trace radioisotopes. Bulk lead exposed to moist air forms a protective layer of varying composition. Lead(II) carbonate
1339-452: A structure, with every alternate layer of oxygen atoms absent. Negative oxidation states can occur as Zintl phases , as either free lead anions, as in Ba 2 Pb, with lead formally being lead(−IV), or in oxygen-sensitive ring-shaped or polyhedral cluster ions such as the trigonal bipyramidal Pb 5 ion, where two lead atoms are lead(−I) and three are lead(0). In such anions, each atom is at
1442-590: Is 6 times higher, copper 10 times, and mild steel 15 times higher); it can be strengthened by adding small amounts of copper or antimony . The melting point of lead—at 327.5 °C (621.5 °F) —is very low compared to most metals. Its boiling point of 1749 °C (3180 °F) is the lowest among the carbon-group elements. The electrical resistivity of lead at 20 °C is 192 nanoohm -meters, almost an order of magnitude higher than those of other industrial metals (copper at 15.43 nΩ·m ; gold 20.51 nΩ·m ; and aluminium at 24.15 nΩ·m ). Lead
1545-661: Is Bryan Davies of Plaid Cymru . The entire county is a Senedd constituency , with its Member of the Senedd being Elin Jones (Plaid Cymru) for the Ceredigion constituency . At Westminster, all of Ceredigion is in the Ceredigion Preseli constituency since 2024, replacing Ceredigion . With Ben Lake (Plaid Cymru) being re-elected as the Member of Parliament in the 2024 election . Farming has traditionally been
1648-520: Is a neurotoxin that accumulates in soft tissues and bones. It damages the nervous system and interferes with the function of biological enzymes , causing neurological disorders ranging from behavioral problems to brain damage, and also affects general health, cardiovascular, and renal systems. Lead's toxicity was first documented by ancient Greek and Roman writers, who noted some of the symptoms of lead poisoning , but became widely recognized in Europe in
1751-466: Is a stub . You can help Misplaced Pages by expanding it . This article related to a river in Wales is a stub . You can help Misplaced Pages by expanding it . Ceredigion Ceredigion ( [kɛrɛˈdɪɡjɔn] ), historically Cardiganshire ( / ˈ k ɑː r d ɪ ɡ ə n ˌ ʃ ɪ ə r , - ʃ ə r / ), is a county in the west of Wales . It borders Gwynedd across the Dyfi estuary to
1854-401: Is a superconductor at temperatures lower than 7.19 K ; this is the highest critical temperature of all type-I superconductors and the third highest of the elemental superconductors. Natural lead consists of four stable isotopes with mass numbers of 204, 206, 207, and 208, and traces of six short-lived radioisotopes with mass numbers 209–214 inclusive. The high number of isotopes
1957-636: Is a coastal county, bordered by Cardigan Bay to the west, Gwynedd to the north, Powys to the east, Carmarthenshire to the south and Pembrokeshire to the south-west. Its area is 1,795 square kilometres (693 sq mi). In 2010 the population was 76,938, making it the second most sparsely populated county in Wales. The main settlements are Aberaeron , Aberporth , Aberystwyth , Borth , Cardigan , Lampeter , Llanarth , Llanddewi Brefi , Llandysul , Llanilar , Llanrhystud , Llanon , New Quay , and Tregaron . The largest of these are Aberystwyth and Cardigan. The Cambrian Mountains cover much of
2060-420: Is a common constituent; the sulfate or chloride may also be present in urban or maritime settings. This layer makes bulk lead effectively chemically inert in the air. Finely powdered lead, as with many metals, is pyrophoric , and burns with a bluish-white flame. Fluorine reacts with lead at room temperature, forming lead(II) fluoride . The reaction with chlorine is similar but requires heating, as
2163-780: Is a mixed sulfide derived from galena; anglesite , PbSO 4 , is a product of galena oxidation; and cerussite or white lead ore, PbCO 3 , is a decomposition product of galena. Arsenic , tin , antimony , silver , gold , copper , bismuth are common impurities in lead minerals. World lead resources exceed two billion tons. Significant deposits are located in Australia, China, Ireland, Mexico, Peru, Portugal, Russia, United States. Global reserves—resources that are economically feasible to extract—totaled 88 million tons in 2016, of which Australia had 35 million, China 17 million, Russia 6.4 million. Typical background concentrations of lead do not exceed 0.1 μg/m in
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#17327756678662266-420: Is a relatively unreactive post-transition metal . Its weak metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases , and it tends to form covalent bonds . Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group . Exceptions are mostly limited to organolead compounds . Like
2369-426: Is a strong oxidizing agent, capable of oxidizing hydrochloric acid to chlorine gas. This is because the expected PbCl 4 that would be produced is unstable and spontaneously decomposes to PbCl 2 and Cl 2 . Analogously to lead monoxide , lead dioxide is capable of forming plumbate anions. Lead disulfide and lead diselenide are only stable at high pressures. Lead tetrafluoride , a yellow crystalline powder,
2472-404: Is a very soft metal with a Mohs hardness of 1.5; it can be scratched with a fingernail. It is quite malleable and somewhat ductile. The bulk modulus of lead—a measure of its ease of compressibility—is 45.8 GPa . In comparison, that of aluminium is 75.2 GPa; copper 137.8 GPa; and mild steel 160–169 GPa. Lead's tensile strength , at 12–17 MPa, is low (that of aluminium
2575-486: Is being developed as West Wales Airport for domestic flights within Wales and the rest of the United Kingdom . The airport is also developing as a centre for the deployment of civil and military unmanned aerial vehicles (UAVs), also known as 'drones'. The airport underwent major improvements in 2008, which extended the length of the runway from 945 to 1,257 m (3,100 to 4,124 ft). Ceredigion Library has
2678-445: Is common for the carbon group. The divalent state is rare for carbon and silicon , minor for germanium, important (but not prevailing) for tin, and is the more important of the two oxidation states for lead. This is attributable to relativistic effects , specifically the inert pair effect , which manifests itself when there is a large difference in electronegativity between lead and oxide , halide , or nitride anions, leading to
2781-408: Is consistent with lead's atomic number being even. Lead has a magic number of protons (82), for which the nuclear shell model accurately predicts an especially stable nucleus. Lead-208 has 126 neutrons, another magic number, which may explain why lead-208 is extraordinarily stable. With its high atomic number, lead is the heaviest element whose natural isotopes are regarded as stable; lead-208
2884-469: Is diversifying into areas such as tourism as farming becomes less profitable. The county is home to the National Library of Wales , Aberystwyth University , and the Lampeter campus of University of Wales Trinity St David . Ceredigion has been inhabited since prehistoric times. A total of 170 hill forts and enclosures have been identified across the county and there are many standing stones dating back to
2987-414: Is exploited in the synthesis of other lead compounds. Few inorganic lead(IV) compounds are known. They are only formed in highly oxidizing solutions and do not normally exist under standard conditions. Lead(II) oxide gives a mixed oxide on further oxidation, Pb 3 O 4 . It is described as lead(II,IV) oxide , or structurally 2PbO·PbO 2 , and is the best-known mixed valence lead compound. Lead dioxide
3090-469: Is hilly and rises to the Cambrian Mountains in the east, where the highest point is Plynlimon at 752 metres (2,467 ft). The mountains are the source of the county's main rivers: the Rheidol , Ystwyth , Aeron and Teifi ; the last of these is Ceredigion's boundary with Carmarthenshire and Pembrokeshire for most of its length. Ceredigion is named after a minor kingdom which occupied approximately
3193-502: Is more prevalent than most other elements with atomic numbers greater than 40. Primordial lead—which comprises the isotopes lead-204, lead-206, lead-207, and lead-208—was mostly created as a result of repetitive neutron capture processes occurring in stars. The two main modes of capture are the s- and r-processes . In the s-process (s is for "slow"), captures are separated by years or decades, allowing less stable nuclei to undergo beta decay . A stable thallium-203 nucleus can capture
Afon Mynach - Misplaced Pages Continue
3296-650: Is not stable, as both the lead(III) ion and the larger complexes containing it are radicals . The same applies for lead(I), which can be found in such radical species. Numerous mixed lead(II,IV) oxides are known. When PbO 2 is heated in air, it becomes Pb 12 O 19 at 293 °C, Pb 12 O 17 at 351 °C, Pb 3 O 4 at 374 °C, and finally PbO at 605 °C. A further sesquioxide , Pb 2 O 3 , can be obtained at high pressure, along with several non-stoichiometric phases. Many of them show defective fluorite structures in which some oxygen atoms are replaced by vacancies: PbO can be considered as having such
3399-741: Is over three and a half times lower than that of the C–C bond . With itself, lead can build metal–metal bonds of an order up to three. With carbon, lead forms organolead compounds similar to, but generally less stable than, typical organic compounds (due to the Pb–C bond being rather weak). This makes the organometallic chemistry of lead far less wide-ranging than that of tin. Lead predominantly forms organolead(IV) compounds, even when starting with inorganic lead(II) reactants; very few organolead(II) compounds are known. The most well-characterized exceptions are Pb[CH(SiMe 3 ) 2 ] 2 and plumbocene . The lead analog of
3502-604: Is rich in archaeological remains such as forts, earthworks and standing stones. Historic sites that can be accessed include Aberystwyth Castle and Cardigan Castle , as well as Strata Florida Abbey . Other visitor attractions include the Cwmystwyth Mines , Llywernog Mine , Devil's Bridge , the Bwlch Nant yr Arian Forest Visitor Centre, Elvis Rock , Cors Caron (Tregaron bog), the Vale of Rheidol Railway , and
3605-415: Is stable, but less so than the difluoride . Lead tetrachloride (a yellow oil) decomposes at room temperature, lead tetrabromide is less stable still, and the existence of lead tetraiodide is questionable. Some lead compounds exist in formal oxidation states other than +4 or +2. Lead(III) may be obtained, as an intermediate between lead(II) and lead(IV), in larger organolead complexes; this oxidation state
3708-413: Is still energetically favorable. Lead, like carbon, is predominantly tetravalent in such compounds. There is a relatively large difference in the electronegativity of lead(II) at 1.87 and lead(IV) at 2.33. This difference marks the reversal in the trend of increasing stability of the +4 oxidation state going down the carbon group; tin, by comparison, has values of 1.80 in the +2 oxidation state and 1.96 in
3811-448: Is the heaviest stable nucleus. (This distinction formerly fell to bismuth , with an atomic number of 83, until its only primordial isotope , bismuth-209, was found in 2003 to decay very slowly.) The four stable isotopes of lead could theoretically undergo alpha decay to isotopes of mercury with a release of energy, but this has not been observed for any of them; their predicted half-lives range from 10 to 10 years (at least 10 times
3914-538: Is the origin of the English word " plumbing ". Its ease of working, its low melting point enabling the easy fabrication of completely waterproof welded joints, and its resistance to corrosion ensured its widespread use in other applications, including pharmaceuticals, roofing, currency, warfare. Writers of the time, such as Cato the Elder , Columella , and Pliny the Elder , recommended lead (and lead-coated) vessels for
4017-525: Is the so-called inert pair effect : the 6s electrons of lead become reluctant to participate in bonding, stabilising the +2 oxidation state and making the distance between nearest atoms in crystalline lead unusually long. Lead's lighter carbon group congeners form stable or metastable allotropes with the tetrahedrally coordinated and covalently bonded diamond cubic structure. The energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp orbitals. In lead,
4120-446: Is usefully exploited: lead tetraacetate is an important laboratory reagent for oxidation in organic synthesis. Tetraethyllead, once added to automotive gasoline, was produced in larger quantities than any other organometallic compound, and is still widely used in fuel for small aircraft . Other organolead compounds are less chemically stable. For many organic compounds, a lead analog does not exist. Lead's per-particle abundance in
4223-487: The Aberystwyth Cliff Railway . Leisure activities available in the county include beach activities, rambling, cycling, sea fishing, canoeing, sailing and horse riding. Many of the towns and villages along the coast have small harbours and facilities for sailing, dolphin watching and other maritime activities. The Ceredigion Coast Path from Cardigan to Ynyslas runs about 60 miles (97 km) along
Afon Mynach - Misplaced Pages Continue
4326-636: The Afon Mynach in a 300 feet (91 m) plunge at the Devil's Bridge chasm. The largest river is the River Teifi which forms the border with Carmarthenshire and Pembrokeshire for part of its length. The towns of Lampeter, Llandysul, Newcastle Emlyn and Cardigan are all in the Teifi Valley, and each has communities on each side of the river, in different counties. Other significant rivers include
4429-620: The Bronze Age . Around the time of the Roman invasion of Britain , the area was between the realms of the Demetae and Ordovices . The Sarn Helen road ran through the territory, with forts at Bremia and Loventium protecting gold mines near present-day Llanddewi Brefi . Following the Roman withdrawal , Irish raids and invasions were repulsed, supposedly by the forces under a northerner named Cunedda . The 9th-century History of
4532-846: The Cambrian Coast Line to Pwllheli . There are no motorways in Ceredigion; the nearest is the western end of the M4 motorway at Pont Abraham , near Pontarddulais in Carmarthenshire . The Fishguard to Bangor trunk road , the A487 , travels in a north-east direction following the coast from Cardigan to New Quay , through Aberaeron and Aberystwyth . The A44 travels eastwards from Aberystwyth to Llangurig , before turning south then east through Rhayader , Leominster and Worcester . There are local bus services between
4635-630: The Phoenicians worked deposits in the Iberian peninsula ; by 1600 BC, lead mining existed in Cyprus , Greece , and Sardinia . Rome's territorial expansion in Europe and across the Mediterranean, and its development of mining, led to it becoming the greatest producer of lead during the classical era , with an estimated annual output peaking at 80,000 tonnes. Like their predecessors,
4738-724: The River Aeron which has its estuary at Aberaeron , and the River Ystwyth and the River Rheidol both of which reach the sea in Aberystwyth harbour . Ceredigion's 50 miles (80 km) of coastline has sandy beaches. In 2011 Ceredigion's beaches were awarded five Blue Flag Awards , four Green Coast Awards , and fourteen Seaside Awards . Ceredigion is one of only two places in the United Kingdom with
4841-671: The Solar System is 0.121 ppb (parts per billion). This figure is two and a half times higher than that of platinum , eight times more than mercury , and seventeen times more than gold . The amount of lead in the universe is slowly increasing as most heavier atoms (all of which are unstable) gradually decay to lead. The abundance of lead in the Solar System since its formation 4.5 billion years ago has increased by about 0.75%. The solar system abundances table shows that lead, despite its relatively high atomic number,
4944-804: The fall of Rome and did not reach comparable levels until the Industrial Revolution . Lead played a crucial role in the development of the printing press , as movable type could be relatively easily cast from lead alloys. In 2014, the annual global production of lead was about ten million tonnes, over half of which was from recycling. Lead's high density, low melting point, ductility and relative inertness to oxidation make it useful. These properties, combined with its relative abundance and low cost, resulted in its extensive use in construction , plumbing , batteries , bullets , shots , weights , solders , pewters , fusible alloys , lead paints , leaded gasoline , and radiation shielding . Lead
5047-401: The nucleus , and more shielded by smaller orbitals. The sum of the first four ionization energies of lead exceeds that of tin, contrary to what periodic trends would predict. This is explained by relativistic effects , which become significant in heavier atoms, which contract s and p orbitals such that lead's 6s electrons have larger binding energies than its 5s electrons. A consequence
5150-468: The +4 state. Lead(II) compounds are characteristic of the inorganic chemistry of lead. Even strong oxidizing agents like fluorine and chlorine react with lead to give only PbF 2 and PbCl 2 . Lead(II) ions are usually colorless in solution, and partially hydrolyze to form Pb(OH) and finally [Pb 4 (OH) 4 ] (in which the hydroxyl ions act as bridging ligands ), but are not reducing agents as tin(II) ions are. Techniques for identifying
5253-563: The Britons attributed to Nennius records that Cunedda's son Ceredig settled the area around the Teifi in the 5th century. The territory supposedly remained a minor kingdom under his dynasty until its extinction upon the drowning of Gwgon ap Meurig c. 871 , after which it was administered by Rhodri Mawr of Gwynedd before passing to his son Cadell , whose son Hywel Dda inherited its neighbouring kingdom Dyfed and established
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#17327756678665356-551: The Church in Wales. Further local government reform under the Local Government (Wales) Act 1994 saw the area become a unitary authority on 1 April 1996. The 1994 act specified that the reformed council was to have both a Welsh and an English name: Sir Aberteifi / Cardiganshire. Before the new arrangements came into force the incoming council resolved to change the name to Ceredigion in both languages. The government agreed
5459-626: The Egyptians had used lead for sinkers in fishing nets , glazes , glasses , enamels , ornaments . Various civilizations of the Fertile Crescent used lead as a writing material , as coins , and as a construction material . Lead was used by the ancient Chinese as a stimulant , as currency , as contraceptive , and in chopsticks . The Indus Valley civilization and the Mesoamericans used it for making amulets ; and
5562-544: The Irish Sea. In the 19th century, many of the rural poor emigrated to the New World from Cardigan, between five and six thousand leaving the town between 1790 and 1860. Aberystwyth became the main centre for the export of lead and Aberaeron and Newquay did brisk coastal trade. The building of the railway from Shrewsbury in the 1860s encouraged visitors, and hotels sprang up in the town to accommodate them. This area of
5665-475: The Romans obtained lead mostly as a by-product of silver smelting. Lead mining occurred in central Europe , Britain , Balkans , Greece , Anatolia , Hispania , the latter accounting for 40% of world production. Lead tablets were commonly used as a material for letters. Lead coffins, cast in flat sand forms and with interchangeable motifs to suit the faith of the deceased, were used in ancient Judea . Lead
5768-558: The United States, Canada, Patagonia and Australia. Furthermore, the owners of the great landed estates, who had for so long dominated the politics of the county, were in many cases heavily in debt. This led to the loss of landowner influence in the running of the county; this became very apparent at the first elections to the Cardiganshire County Council in 1889. By the second half of the 20th century,
5871-452: The abbey and Llanbadarn Fawr were important monastic sites of scholarship and education. Place names including ysbyty denote their association with pilgrims. In 1282, Edward I of England conquered the principality of Wales and divided the area into counties. One of thirteen traditional counties in Wales . Cardiganshire was split into the five hundreds of Genau'r-Glyn, Ilar, Moyddyn, Penarth and Troedyraur. Much later, Cardiganshire
5974-521: The area of the county in the fifth century AD. The contemporary county has the same borders as Cardiganshire, which was established in 1282 by the English king Edward I after his conquest of Wales . In the 18th and early 19th centuries, the county was more industrialised than it is today; lead , silver and zinc were mined in the area, and Cardigan was the largest port in South Wales. The economy later became highly dependent on dairy farming , but
6077-607: The atmosphere; 100 mg/kg in soil; 4 mg/kg in vegetation, 5 μg/L in fresh water and seawater. The modern English word lead is of Germanic origin; it comes from the Middle English leed and Old English lēad (with the macron above the "e" signifying that the vowel sound of that letter is long). The Old English word is derived from the hypothetical reconstructed Proto-Germanic * lauda- ('lead'). According to linguistic theory, this word bore descendants in multiple Germanic languages of exactly
6180-472: The basis of Cardiganshire's economy, with dairying and stock-rearing being the main occupations. Before the first railway was built in 1866, the stock used to be herded over the mountains to England, where Rugby , Northampton and London were important destinations. At one time there was a sizeable mining industry in Cardiganshire, but the reserves of lead, silver and zinc became unprofitable to mine by
6283-623: The capital of Welsh culture. The National Library of Wales is at Aberystwyth and there is information on local history at the Ceredigion Museum . There is a technical museum Internal Fire – Museum of Power , which is at Tan-y-groes near the coast road. Stately homes in the county open to the public include the Hafod Estate and Llanerchaeron . It is home to the Aberystwyth Arts Centre . The county
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#17327756678666386-501: The centres of Methodism in Wales; the Aeron Valley was at the centre of the revival. Cardigan was one of the major ports of southern Wales until its harbour silted in the mid-19th century. The Industrial Revolution passed by, not much affecting the area. In the uplands, wheeled vehicles were rare in the 18th century, and horses and sleds were still being used for transport. On the coast, herrings and corn were traded across
6489-401: The change of name, which took effect on 2 April 1996, one day after the new authority formally came into being. A referendum was held on 20 May 2004 on whether to have a directly elected mayor for the county, which would have been the first in Wales. The Llais Ceredigion political initiative had been formed with this aim, but the proposal was rejected. As of 2024, the council leader
6592-490: The coast with spectacular scenery. It can conveniently be divided into seven sections. When Dylan Thomas lived in New Quay and Talsarn, he frequented Aberaeron and Lampeter. The Dylan Thomas Trail links places associated with him. The Welsh Government's Visit Wales website describes the River Teifi as "one of the major game rivers of Wales," although there has been concern that salmon stocks are in decline. There are
6695-532: The county of Dyfed became a district of Wales under the name Ceredigion in 1974 under the Local Government Act 1972 , and since 1996, has formed the county of Ceredigion. According to the 2021 census 45.3% of the population can speak Welsh , the third highest proportion after Gwynedd and the Isle of Anglesey . Nevertheless, this was a decline from 47.3% in 2011 and 52% in 2001. Ceredigion
6798-479: The county was governed by Cardiganshire County Council , which took over the local government functions of the quarter sessions . The county council was abolished in 1974 by the Local Government Act 1972 , with the area becoming the lower-tier district of Ceredigion within the larger county of Dyfed . Until 1974, Cardiganshire had been governed locally by civil parishes ; these in large part equated to ecclesiastical parishes , most of which still exist as part of
6901-489: The course of the Earth's history, have remained in the crust instead of sinking deeper into the Earth's interior. This accounts for lead's relatively high crustal abundance of 14 ppm; it is the 36th most abundant element in the crust. The main lead-bearing mineral is galena (PbS), which is mostly found with zinc ores. Most other lead minerals are related to galena in some way; boulangerite , Pb 5 Sb 4 S 11 ,
7004-419: The current age of the universe). Three of the stable isotopes are found in three of the four major decay chains : lead-206, lead-207, and lead-208 are the final decay products of uranium-238 , uranium-235 , and thorium-232 , respectively. These decay chains are called the uranium chain , the actinium chain , and the thorium chain . Their isotopic concentrations in a natural rock sample depends greatly on
7107-428: The diiodide . Many lead(II) pseudohalides are known, such as the cyanide, cyanate, and thiocyanate . Lead(II) forms an extensive variety of halide coordination complexes , such as [PbCl 4 ] , [PbCl 6 ] , and the [Pb 2 Cl 9 ] n chain anion. Lead(II) sulfate is insoluble in water, like the sulfates of other heavy divalent cations . Lead(II) nitrate and lead(II) acetate are very soluble, and this
7210-536: The early 20th century. Shipping was also important in the county, with coal and lime being imported in coastal vessels, and mineral ores and oak bark for tanning being exported. Shipbuilding was an important industry: most of Wales' sailing vessels were built in Cardiganshire. Cardiganshire had a substantial population in the early modern period, but this declined during the 19th century as wider social and economic developments affected all aspects of Cardiganshire life. Traditional industries were in decline, agriculture
7313-621: The east of the county; this large area forms part of the desert of Wales . In the south and west, the surface is less elevated. The highest point is Plynlimon (Pumlumon) at 2,467 feet (752 m), other Marilyns include Pen y Garn and Llan Ddu Fawr . On the slopes of Pumlumon five rivers have their sources: the Severn , the Wye , the Dulas , the Llyfnant and the Rheidol , the last of which meets
7416-525: The eastern and southern Africans used lead in wire drawing . Because silver was extensively used as a decorative material and an exchange medium, lead deposits came to be worked in Asia Minor from 3000 BC; later, lead deposits were developed in the Aegean and Laurion . These three regions collectively dominated production of mined lead until c. 1200 BC . Beginning c. 2000 BC,
7519-578: The element its chemical symbol Pb . The word * ɸloud-io- is thought to be the origin of Proto-Germanic * bliwa- (which also means 'lead'), from which stemmed the German Blei . The name of the chemical element is not related to the verb of the same spelling, which is derived from Proto-Germanic * laidijan- ('to lead'). Metallic lead beads dating back to 7000–6500 BC have been found in Asia Minor and may represent
7622-413: The first example of metal smelting . At that time, lead had few (if any) applications due to its softness and dull appearance. The major reason for the spread of lead production was its association with silver, which may be obtained by burning galena (a common lead mineral). The Ancient Egyptians were the first to use lead minerals in cosmetics, an application that spread to Ancient Greece and beyond;
7725-430: The group. Lead dihalides are well-characterized; this includes the diastatide and mixed halides, such as PbFCl. The relative insolubility of the latter forms a useful basis for the gravimetric determination of fluorine. The difluoride was the first solid ionically conducting compound to be discovered (in 1834, by Michael Faraday ). The other dihalides decompose on exposure to ultraviolet or visible light, especially
7828-427: The highest proportions of its population working in agriculture, forestry and fishing, close behind such other places as Orkney and Shetland . Exposed, marginal land is also used for wind farms : Cefn Croes Wind Farm near Devil's Bridge has 39 turbines and a nominal capacity of 58.5 MW. Farm incomes have been in decline over the years; and, as well as being a European Objective I area , in 2001 Ceredigion
7931-449: The inert pair effect increases the separation between its s- and p-orbitals, and the gap cannot be overcome by the energy that would be released by extra bonds following hybridization. Rather than having a diamond cubic structure, lead forms metallic bonds in which only the p-electrons are delocalized and shared between the Pb ions. Lead consequently has a face-centered cubic structure like
8034-447: The late 19th century AD. A lead atom has 82 electrons , arranged in an electron configuration of [ Xe ]4f 5d 6s 6p . The sum of lead's first and second ionization energies —the total energy required to remove the two 6p electrons—is close to that of tin , lead's upper neighbor in the carbon group . This is unusual; ionization energies generally fall going down a group, as an element's outer electrons become more distant from
8137-560: The latter being stable only above around 488 °C. Litharge is the most commonly used inorganic compound of lead. There is no lead(II) hydroxide; increasing the pH of solutions of lead(II) salts leads to hydrolysis and condensation. Lead commonly reacts with heavier chalcogens. Lead sulfide is a semiconductor , a photoconductor , and an extremely sensitive infrared radiation detector . The other two chalcogenides, lead selenide and lead telluride , are likewise photoconducting. They are unusual in that their color becomes lighter going down
8240-441: The latter is not; this allows for lead–lead dating . As uranium decays into lead, their relative amounts change; this is the basis for uranium–lead dating . Lead-207 exhibits nuclear magnetic resonance , a property that has been used to study its compounds in solution and solid state, including in the human body. Apart from the stable isotopes, which make up almost all lead that exists naturally, there are trace quantities of
8343-461: The lighter members of the group, lead tends to bond with itself ; it can form chains and polyhedral structures. Since lead is easily extracted from its ores , prehistoric people in the Near East were aware of it . Galena is a principal ore of lead which often bears silver. Interest in silver helped initiate widespread extraction and use of lead in ancient Rome . Lead production declined after
8446-422: The main centres of population, with long distance services between Aberystwyth and Cardiff , via Aberaeron and Lampeter . A bus service known as Bwcabus operates in the south of the county, offering customised transport for rural dwellers. TrawsCymru T1 service runs between Aberystwyth and Carmarthen, with some journeys through Aberaeron and Lampeter. Aberporth Airport , located south-east of Aberporth ,
8549-590: The most important industries. In addition, two universities are within the county boundaries: Aberystwyth University and the Lampeter campus of the University of Wales, Trinity Saint David . The Welsh Plant Breeding Station is near Aberystwyth and linked to the University. The National Library of Wales , founded in 1907, is also in Aberystwyth. Ceredigion is an extremely rural county; the largest town, Aberystwyth, has fewer than 15,000 permanent residents and
8652-539: The neutrons are arranged in complete shells in the atomic nucleus, and it becomes harder to energetically accommodate more of them. When the neutron flux subsides, these nuclei beta decay into stable isotopes of osmium , iridium , platinum . Lead is classified as a chalcophile under the Goldschmidt classification , meaning it is generally found combined with sulfur. It rarely occurs in its native , metallic form. Many lead minerals are relatively light and, over
8755-457: The north, Powys to the east, Carmarthenshire and Pembrokeshire to the south, and the Irish Sea to the west. Aberystwyth is the largest settlement and, together with Aberaeron , is an administrative centre of Ceredigion County Council . The county is the second most sparsely populated in Wales, with an area of 688 square miles (1,780 km ) and a population of 71,500; the latter is
8858-637: The population was increasing again. More retired people were arriving to make their home in the tranquil surroundings, and after the Beacham Commission in the 1960s, the British government realised that the rural way of life in parts of Wales was in crisis, and started to react. Through government initiatives and local actions, opportunities in tourism, rural crafts, specialist food shops, farmers' markets and added-value food products began to emerge. However, in 2011, at 3.1%, Ceredigion still had one of
8961-418: The preparation of sweeteners and preservatives added to wine and food. The lead conferred an agreeable taste due to the formation of "sugar of lead" ( lead(II) acetate ), whereas copper vessels imparted a bitter flavor through verdigris formation. This metal was by far the most used material in classical antiquity, and it is appropriate to refer to the (Roman) Lead Age. Lead was to the Romans what plastic
9064-414: The presence of the Pb ion in water generally rely on the precipitation of lead(II) chloride using dilute hydrochloric acid. As the chloride salt is sparingly soluble in water, in very dilute solutions the precipitation of lead(II) sulfide is instead achieved by bubbling hydrogen sulfide through the solution. Lead monoxide exists in two polymorphs , litharge α-PbO (red) and massicot β-PbO (yellow),
9167-422: The presence of these three parent uranium and thorium isotopes. For example, the relative abundance of lead-208 can range from 52% in normal samples to 90% in thorium ores; for this reason, the standard atomic weight of lead is given to only one decimal place. As time passes, the ratio of lead-206 and lead-207 to lead-204 increases, since the former two are supplemented by radioactive decay of heavier elements while
9270-432: The r-process (r is for "rapid"), captures happen faster than nuclei can decay. This occurs in environments with a high neutron density, such as a supernova or the merger of two neutron stars . The neutron flux involved may be on the order of 10 neutrons per square centimeter per second. The r-process does not form as much lead as the s-process. It tends to stop once neutron-rich nuclei reach 126 neutrons. At this point,
9373-487: The realm of Deheubarth . Records are highly obscure; some historians believe that Hyfaidd ap Bledrig , the Dyfed ruler, may have annexed Ceredigion before his heirs lost it to Hywel through war. Many pilgrims passed through Cardiganshire on their way to St Davids . Some came by sea and made use of the churches at Mwnt and Penbryn , while others came by land seeking hospitality at such places as Strata Florida Abbey . Both
9476-510: The remainder of the population of the county is scattered over 150 small towns, villages and hamlets. According to the 2011 UK census the population of Ceredigion was around 75,900. By the time the 2021 UK census was taken this had fallen by 5.8% to 71,500. The county has no large commercial areas. The nearest substantial settlements are located at least 1 hour 45 minutes drive away. Approximate road distances from Ceredigion's largest town, Aberystwyth, are: Swansea , 75 miles (121 km) to
9579-541: The resulting chloride layer diminishes the reactivity of the elements. Molten lead reacts with the chalcogens to give lead(II) chalcogenides. Lead metal resists sulfuric and phosphoric acid but not hydrochloric or nitric acid ; the outcome depends on insolubility and subsequent passivation of the product salt. Organic acids, such as acetic acid , dissolve lead in the presence of oxygen. Concentrated alkalis dissolve lead and form plumbites . Lead shows two main oxidation states: +4 and +2. The tetravalent state
9682-451: The river plunges 90 metres into the gorge of the River Rheidol . It is also famous for the three bridges built one on top of the other in the same village, the lowest of the three said to be built by the devil (hence the name Devil's Bridge), but most probably built by the monks of Strata Florida . 52°22′37″N 3°51′00″W / 52.377°N 3.850°W / 52.377; -3.850 This Ceredigion location article
9785-518: The same meaning. There is no consensus on the origin of the Proto-Germanic * lauda- . One hypothesis suggests it is derived from Proto-Indo-European * lAudh- ('lead'; capitalization of the vowel is equivalent to the macron). Another hypothesis suggests it is borrowed from Proto-Celtic * ɸloud-io- ('lead'). This word is related to the Latin plumbum , which gave
9888-491: The similarly sized divalent metals calcium and strontium . Pure lead has a bright, shiny gray appearance with a hint of blue. It tarnishes on contact with moist air and takes on a dull appearance, the hue of which depends on the prevailing conditions. Characteristic properties of lead include high density , malleability, ductility, and high resistance to corrosion due to passivation . Lead's close-packed face-centered cubic structure and high atomic weight result in
9991-588: The simplest organic compound , methane , is plumbane . Plumbane may be obtained in a reaction between metallic lead and atomic hydrogen. Two simple derivatives, tetramethyllead and tetraethyllead , are the best-known organolead compounds. These compounds are relatively stable: tetraethyllead only starts to decompose if heated or if exposed to sunlight or ultraviolet light. With sodium metal, lead readily forms an equimolar alloy that reacts with alkyl halides to form organometallic compounds such as tetraethyllead. The oxidizing nature of many organolead compounds
10094-647: The south; Shrewsbury , 76 miles (122 km) to the east, in the English county of Shropshire ; and Wrexham , 82 miles (132 km) to the northeast. The capital, Cardiff , is over 100 miles (160 km) from most parts of the county. Although Ceredigion and Gwynedd share a boundary, it is not possible to travel directly between the two by land as all road and rail links avoid the Dyfi estuary and pass through Dyfi Junction or Machynlleth in Powys. Between 1889 and 1974,
10197-403: The very rare cluster decay of radium-223, one of the daughter products of natural uranium-235, and the decay chain of neptunium-237, traces of which are produced by neutron capture in uranium ores. Lead-213 also occurs in the decay chain of neptunium-237. Lead-210 is particularly useful for helping to identify the ages of samples by measuring its ratio to lead-206 (both isotopes are present in
10300-578: Was designated a regional "Tourist growth area" by the Wales Tourist Board . There is little industry other than farming, so tourism plays an important part in the county's economy. Visitors stay in hotels, guest houses and homes offering bed-and-breakfast, self-catering cottages, caravans and camp sites; they spend money in local shops, dine in local establishments and visit the county's many attractions. Ceredigion prides itself on offering an unspoilt natural landscape, and Aberystwyth claims to be
10403-425: Was designated as a vice-county . Pen-y-wenallt was home to 17th century theologian and author, Theophilus Evans . In the 18th century there was an evangelical revival of Christianity, and nonconformism became established in the county as charismatic preachers like Daniel Rowland of Llangeitho attracted large congregations. Every community built its own chapel or meeting house, and Cardiganshire became one of
10506-425: Was in decline and it was becoming increasingly difficult for a still-rising population to earn a living within their native parishes and communities. By the first half of the 20th century, falling livestock prices and greater international competition made farming unprofitable. Many residents of Cardiganshire moved to other parts of South Wales, where there were better employment opportunities, and many more emigrated to
10609-534: Was used to make sling bullets from the 5th century BC. In Roman times, lead sling bullets were amply used, and were effective at a distance of between 100 and 150 meters. The Balearic slingers , used as mercenaries in Carthaginian and Roman armies, were famous for their shooting distance and accuracy. Lead was used for making water pipes in the Roman Empire ; the Latin word for the metal, plumbum ,
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