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In 1817 the German chemist Leopold Gmelin divided the elements into nonmetals, light metals, and heavy metals. [54] Light metals had densities of 0.860–5.0 g/cm 3; heavy metals 5.308–22.000. [55] The term later became associated with elements of high atomic weight or high atomic number.
A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
A toxic heavy metal is a common but misleading term for a metal-like element noted for its potential toxicity. [4] Not all heavy metals are toxic and some toxic metals are not heavy. [ 5 ] Elements often discussed as toxic include cadmium , mercury and lead , [ 6 ] all of which appear in the World Health Organization 's list of 10 chemicals of ...
41 of the 118 known elements have names associated with, or specifically named for, places around the world or among astronomical objects. 32 of these have names tied to the places on Earth, and the other nine are named after to Solar System objects: helium for the Sun; tellurium for the Earth; selenium for the Moon; mercury (indirectly), uranium, neptunium and plutonium after their respective ...
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Finite element analysis – Flange-Fluid mechanics – Flywheel – Force – an influence that can push or pull an object to change its motion. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. A force has both magnitude and direction, making it a vector quantity. Force ...
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
Alloy –is a combination of metals or of a metal and another element. Alloys are defined by a metallic bonding character. [3] An alloy may be a solid solution of metal elements (a single phase) or a mixture of metallic phases (two or more solutions). Intermetallic compounds are alloys with a defined stoichiometry and crystal structure.