Molecule

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A molecule is the smallest amount of a chemical substance that can exist. If a molecule were split into smaller pieces, it would be a different substance.^[1]

Molecules are made up of atoms that are stuck together in a particular shape or form. Not all combinations of atoms are equally possible; atoms make certain shapes in preference to others. Also, they have different valency. For example, oxygen atoms always have two bonds with other atoms, carbon atoms always have four bonds with other atoms, and nitrogen atoms always have three bonds with other atoms.^[2]

In the kinetic theory of gases, the term molecule is often used for any gaseous particle regardless of its composition. According to this definition, noble gas atoms are considered molecules as they are in fact monoatomic molecules.^[3]

In gases like air, the molecules are just flying around. In liquids like water, the molecules are stuck together but they can still move. In solids like sugar, the molecules can only vibrate. In the fourth state of matter known as plasma, the atoms are ionized and cannot form molecules.

With a molecular formula, you can write down the numbers of all atoms in a molecule. For example, the molecular formula of glucose is C₆H₁₂O₆. That means that one molecule of glucose is made up of six carbon atoms, twelve hydrogen atoms and six oxygen atoms.^[4]

1. ↑ Gold, Victor, ed. (2019). The IUPAC Compendium of Chemical Terminology: The Gold Book (4 ed.). Research Triangle Park, NC: International Union of Pure and Applied Chemistry (IUPAC). doi:10.1351/goldbook.m04002.
2. ↑ Chemistry : the central science. Theodore L. Brown, Theodore L. Brown (9th ed.). Upper Saddle River, NJ: Prentice Hall. 2002. ISBN 0-13-066997-0. OCLC 47953855.{{cite book}}: CS1 maint: others (link)
3. ↑ Chandra, Sulekh (2005). Comprehensive Inorganic Chemistry. New Age Publishers. ISBN 81-224-1512-1.
4. ↑ Chang, Raymond (1998). Chemistry (6th ed.). Boston, Mass.: McGraw-Hill. ISBN 0-07-115221-0. OCLC 711906521.