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118 chemical elements have been identified and named officially by IUPAC.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).
The American Petroleum Institute gravity, or API gravity, is a measure of how heavy or light a petroleum liquid is compared to water: if its API gravity is greater than 10, it is lighter and floats on water; if less than 10, it is heavier and sinks.
Gallium is a chemical element; it has the symbol Ga and atomic number 31. Discovered by the French chemist Paul-Émile Lecoq de Boisbaudran in 1875, [ 10 ] gallium is in group 13 of the periodic table and is similar to the other metals of the group ( aluminium , indium , and thallium ).
Sulfur (also spelled sulphur in British English) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with the chemical formula S 8. Elemental sulfur is a bright yellow, crystalline solid at room temperature.
Before the ready availability of statistical software having the ability to evaluate probability distribution functions accurately, continuity corrections played an important role in the practical application of statistical tests in which the test statistic has a discrete distribution: it had a special importance for manual calculations.
Although the chemical formula for THC (C 21 H 30 O 2) describes multiple isomers, [10] the term THC usually refers to the delta-9-THC isomer with chemical name (−)-trans-Δ 9-tetrahydrocannabinol. It is a colorless oil.
Unlike ammonia, phosphine is oxidised by air. Phosphine is also far less basic than ammonia. Other phosphines are known which contain chains of up to nine phosphorus atoms and have the formula P n H n+2. [16] The highly flammable gas diphosphine (P 2 H 4) is an analogue of hydrazine.
Relativistic quantum chemistry combines relativistic mechanics with quantum chemistry to calculate elemental properties and structure, especially for the heavier elements of the periodic table. A prominent example is an explanation for the color of gold : due to relativistic effects, it is not silvery like most other metals.