86 articles
Group 3 element
Group 3 of the periodic table contains scandium and yttrium, with its lower members disputed: lanthanum and actinium traditionally, or lutetium and lawrencium, and IUPAC found no objective criterion.
Hafnium
Hafnium is a corrosion-resistant transition metal, atomic number 72, discovered in Copenhagen in 1923, known for neutron absorption in nuclear reactor control rods and its oxide in microchips.
Hallmark
A hallmark is an official mark certifying that an item of gold, silver, platinum, or palladium has been tested and meets legal standards of purity.
Heavy metals
Heavy metals is a loosely defined term, considered deprecated by IUPAC, grouping metals linked with pollution and toxicity; lead, mercury, cadmium, and arsenic raise the main health concerns.
Hexavalent chromium
Hexavalent chromium, also called chromium-6 or Cr(VI), is chromium in the +6 oxidation state and a known human carcinogen used in electroplating, welding, and stainless steel production.
Holmium
Holmium is a silvery chemical element with symbol Ho and atomic number 67, a rare earth metal with the strongest magnetic moment of any element.
Iridium
Iridium is a hard, silvery-white platinum-group metal, the most corrosion-resistant element known, discovered in 1803 and famous for the asteroid-impact layer marking the dinosaur extinction.
Iron
Iron (Fe) is a silvery-gray metal, the most widely used of all metals, the principal constituent of steel, and an essential nutrient for nearly all life.
Lanthanide
The lanthanides, also called lanthanoids, are the fifteen metallic elements with atomic numbers 57 through 71, from lanthanum to lutetium, part of the rare earths.
Lanthanide contraction
The lanthanide contraction is the steady decrease in atomic and ionic radii of the lanthanide elements from lanthanum to lutetium, caused by poor shielding by 4f electrons.
Lanthanum
Lanthanum is a soft, silvery-white metallic element with atomic number 57, the first of the lanthanide series, discovered by Carl Gustav Mosander in Sweden in 1839.
List of inorganic compounds
The list of inorganic compounds, also called inorganic compounds by element, covers compounds such as salts, oxides, halides, and coordination complexes, named under IUPAC's stoichiometric and additive systems.
Lutetium
Lutetium, also called cassiopeium, is a silvery-white metal, atomic number 71 and the heaviest lanthanide, discovered in 1907 and named after Lutetia, the Latin name for Paris.
Manganese
Manganese (Mn, atomic number 25) is a hard, brittle silvery transition metal isolated in 1774, used mainly in steelmaking and essential to photosynthesis and all known living organisms.
Molybdenum
Molybdenum is a hard, silvery group 6 transition metal with the sixth highest melting point of any element, best known for strengthening steel and for its role in enzymes.
Neodymium
Neodymium is a chemical element with atomic number 60, a silvery lanthanide metal discovered in 1885 and best known as the key ingredient of the strongest permanent magnets.
Nickel
Nickel is a silvery-white, ferromagnetic transition metal, element 28 in the periodic table, valued for corrosion resistance and central to stainless steel, superalloys, and lithium-ion battery cathodes.
Niobium
Niobium, symbol Nb and atomic number 41, is a corrosion-resistant transition metal used chiefly to strengthen steel and in superconducting magnets for MRI scanners and accelerators.
Niobium alloys
Niobium alloys are metallic alloys based on niobium, a refractory metal with a melting point of 2477 °C, used in rocket nozzles, jet engines, superconductors, and medical implants.
Noble metal
A noble metal is a metallic element highly resistant to corrosion and oxidation, such as gold, silver, and platinum, usually found in nature in its raw form.
Oligodynamic effect
The oligodynamic effect, or oligodynamic action, is the biocidal action of trace metal ions against bacteria, fungi, and viruses, described by Carl von Nägeli in 1893.
Orichalcum
Orichalcum, Greek oreichalkos, is the classical name for a copper-zinc alloy like brass. In Roman times it was the metal of sestertius and dupondius coins, and Plato linked it to Atlantis.
Osmium
Osmium is a hard, bluish-silver platinum-group metal, atomic number 76, often cited as the densest element, discovered in 1803 and known for its very toxic tetroxide and hard, wear-resistant alloys.
Palladium
Palladium (Pd, atomic number 46) is a silvery-white transition metal of the platinum group, discovered by William Hyde Wollaston in 1803 and best known as the active metal in automotive catalytic converters.
Platinum
Platinum is a chemical element with symbol Pt and atomic number 78, a dense, silvery-white metal best known for catalytic converters, jewelry, and the cancer drug cisplatin.
Platinum group
The platinum group is a set of six chemically similar transition metals: platinum, palladium, rhodium, ruthenium, iridium, and osmium, mostly mined in South Africa, Zimbabwe, and Russia.
Praseodymium
Praseodymium is a soft, silvery lanthanide metal with atomic number 59, best known as a substitute for neodymium in magnets and as part of didymium glass.
Precious metal
A precious metal is a rare, naturally occurring metallic element of high economic value, resistant to corrosion; the class is usually taken to include gold, silver, and the six platinum-group metals.
Protactinium
Protactinium is a dense, silvery, highly radioactive actinide metal, atomic number 91, occurring naturally only as a decay product of uranium and among the rarest elements.
Radionuclide
A radionuclide, also known as a radioisotope or radioactive isotope, is an unstable atom that spontaneously decays, emitting radiation such as alpha and beta particles until it becomes stable.