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[16] [17] [18] A molecule may be homonuclear, that is, it consists of atoms of one chemical element, as with two atoms in the oxygen molecule (O 2); or it may be heteronuclear, a chemical compound composed of more than one element, as with water (two hydrogen atoms and one oxygen atom; H 2 O). A molecule is the smallest unit of a substance that ...
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 visualization 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 ...
The law of definite proportion was given by Joseph Proust in 1797. [2]I shall conclude by deducing from these experiments the principle I have established at the commencement of this memoir, viz. that iron like many other metals is subject to the law of nature which presides at every true combination, that is to say, that it unites with two constant proportions of oxygen.
The following are subcategories containing chemical compounds by element. An alternative listing of inorganic compounds may be found at inorganic compounds by element . Wikimedia Commons has media related to Chemical compounds by element .
This comprises all organic and inorganic compounds, elements, reagents, commodities, pharmaceuticals, pollutants, and other large-scale and small-scale chemicals of interest. Additional focus is given to the selected articles about approx 400 representative chemicals, on the target worklist.
The following outline acts as an overview of and topical guide to chemistry: . Chemistry is the science of atomic matter (matter that is composed of chemical elements), especially its chemical reactions, but also including its properties, structure, composition, behavior, and changes as they relate to the chemical reactions.
Modern simultaneous CHNS combustion analyzer. Elemental analysis is a process where a sample of some material (e.g., soil, waste or drinking water, bodily fluids, minerals, chemical compounds) is analyzed for its elemental and sometimes isotopic composition.
The name of the cation (the unmodified element name for monatomic cations) comes first, followed by the name of the anion. [100] [101] For example, MgCl 2 is named magnesium chloride, and Na 2 SO 4 is named sodium sulfate (SO 2− 4, sulfate, is an example of a polyatomic ion).