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The solid or liquid state of metals largely originates in the capacity of the metal atoms involved to readily lose their outer shell electrons. Broadly, the forces holding an individual atom's outer shell electrons in place are weaker than the attractive forces on the same electrons arising from interactions between the atoms in the solid or liquid metal. The electrons involved become delocalised and the atomic structure of a metal can effectively be visualised as a collection of atoms embedded in a cloud of relatively mobile electrons. This type of interaction is called a metallic bond. [6] The strength of metallic bonds for different elemental metals reaches a maximum around the center of the transition metal series, as these elements have large numbers of delocalized electrons. [n 1] The high reflectivity of some metals enables their use in mirrors, including precision astronomical instruments, and adds to the aesthetics of metallic jewelry. About the Editors". Metals, Microbes, and Minerals – the Biogeochemical Side of Life. De Gruyter. 2021. pp.v–vi. doi: 10.1515/9783110589771-001. ISBN 9783110589771. S2CID 242357865.
Painting, anodizing, or plating metals are good ways to prevent their corrosion. However, a more reactive metal in the electrochemical series must be chosen for coating, especially when chipping of the coating is expected. Water and the two metals form an electrochemical cell and, if the coating is less reactive than the underlying metal, the coating actually promotes corrosion. The elemental metals have electrical conductivity values of from 6.9 × 10 3 S/cm for manganese to 6.3 × 10 5 S/cm for silver. In contrast, a semiconducting metalloid such as boron has an electrical conductivity 1.5 × 10 −6 S/cm. With one exception, metallic elements reduce their electrical conductivity when heated. Plutonium increases its electrical conductivity when heated in the temperature range of around −175 to +125°C. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nded.). Butterworth-Heinemann. ISBN 978-0-08-037941-8. Aluminium was discovered in 1824 but it was not until 1886 that an industrial large-scale production method was developed. Prices of aluminium dropped and aluminium became widely used in jewelry, everyday items, eyeglass frames, optical instruments, tableware, and foil in the 1890s and early 20th century. Aluminium's ability to form hard yet light alloys with other metals provided the metal many uses at the time. During World War I, major governments demanded large shipments of aluminium for light strong airframes. The most common metal in use for electric power transmission today is aluminium-conductor steel-reinforced. Also seeing much use is all-aluminium-alloy conductor. Aluminium is used because it has about half the weight of a comparable resistance copper cable (though larger diameter due to lower specific conductivity), as well as being cheaper. Copper was more popular in the past and is still in use, especially at lower voltages and for grounding. Some chemical elements are called metals. Most elements in the periodic table are metals. These elements usually have the following traits:A metal may be a chemical element such as iron; an alloy such as stainless steel; or a molecular compound such as polymeric sulfur nitride. [1]
Once the ore is mined, the metals must be extracted, usually by chemical or electrolytic reduction. Pyrometallurgy uses high temperatures to convert ore into raw metals, while hydrometallurgy employs aqueous chemistry for the same purpose. The methods used depend on the metal and their contaminants.Rare metals with high value, like gold, silver and platinum are often used to make jewellery. Metals are also used to make fasteners and screws. Pots used for cooking can be made from copper, aluminium, steel or iron. Lead is very heavy and dense and can be used as ballast in boats to stop them from turning over, or to protect people from ionizing radiation. Heavier metals are not usually formed this way since fusion reactions involving such nuclei would consume rather than release energy. [18] Rather, they are largely synthesised (from elements with a lower atomic number) by neutron capture, with the two main modes of this repetitive capture being the s-process and the r-process. In the s-process ("s" stands for "slow"), singular captures are separated by years or decades, allowing the less stable nuclei to beta decay, [19] while in the r-process ("rapid"), captures happen faster than nuclei can decay. Therefore, the s-process takes a more-or-less clear path: for example, stable cadmium-110 nuclei are successively bombarded by free neutrons inside a star until they form cadmium-115 nuclei which are unstable and decay to form indium-115 (which is nearly stable, with a half-life 30 000 times the age of the universe). These nuclei capture neutrons and form indium-116, which is unstable, and decays to form tin-116, and so on. [17] [20] [n 4] In contrast, there is no such path in the r-process. The s-process stops at bismuth due to the short half-lives of the next two elements, polonium and astatine, which decay to bismuth or lead. The r-process is so fast it can skip this zone of instability and go on to create heavier elements such as thorium and uranium. [22] Most metals are solid at room temperature, but this does not have to be the case. Mercury is liquid. Alloys are mixtures, where at least one part of the mixture is a metal. Examples of metals are aluminium, copper, iron, tin, gold, lead, silver, titanium, uranium, and zinc. Well-known alloys include bronze and steel. Metals are usually inclined to form cations through electron loss. [6] Most will react with oxygen in the air to form oxides over various timescales ( potassium burns in seconds while iron rusts over years). Some others, like palladium, platinum, and gold, do not react with the atmosphere at all. The oxides of metals are generally basic, as opposed to those of nonmetals, which are acidic or neutral. Exceptions are largely oxides with very high oxidation states such as CrO 3, Mn 2O 7, and OsO 4, which have strictly acidic reactions.
However, some metals are different. An example is the metal sodium. It is soft, melts at a low temperature, and is so light, it floats on water. People should not try this though, because another property of sodium is that it explodes when it touches water. In chemistry, metal is a word for a group of chemical elements that have certain properties. It is easy for the atoms of a metal to lose an electron and become positive ions, or cations. In this way, metals are not like the other two kinds of elements - the nonmetals and the metalloids. Most elements on the periodic table are metals. Potassium and sodium are much too dangerous to react with dilute acid! The reaction is dangerously fast and potentially explosive. Summary Metal In astrophysics the term "metal" is cast more widely to refer to all chemical elements in a star that are heavier than helium, and not just traditional metals. In this sense the first four "metals" collecting in stellar cores through nucleosynthesis are carbon, nitrogen, oxygen, and neon, all of which are strictly non-metals in chemistry. A star fuses lighter atoms, mostly hydrogen and helium, into heavier atoms over its lifetime. Used in that sense, the metallicity of an astronomical object is the proportion of its matter made up of the heavier chemical elements. [3] [4]Tylecote, R. F. (1992). A History of Metallurgy, Second Edition. London: Maney Publishing, for the Institute of Materials. ISBN 978-1-902653-79-2. Archived from the original on 2015-04-02. Von Welsbach, in 1906, proved that the old ytterbium also contained a new element (#71), which he named cassiopeium. Urbain proved this simultaneously, but his samples were very impure and only contained trace quantities of the new element. Despite this, his chosen name lutetium was adopted. The demand for precious metals is driven not only by their practical use, but also by their role as investments and a store of value. [16] Palladium and platinum, as of fall 2018, were valued at about three quarters the price of gold. Silver is substantially less expensive than these metals, but is often traditionally considered a precious metal in light of its role in coinage and jewelry. Georges Urbain claimed to have found element 72 in rare-earth residues, while Vladimir Vernadsky independently found it in orthite. Neither claim was confirmed due to World War I, and neither could be confirmed later, as the chemistry they reported does not match that now known for hafnium. After the war, in 1922, Coster and Hevesy found it by X-ray spectroscopic analysis in Norwegian zircon. Hafnium was thus the last stable element to be discovered, though rhenium was the last to be correctly recognized. Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego: Academic Press. ISBN 0-12-352651-5.
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