What is Molecule?
{{one source|date=April 2021}} [[File:Glucose.PNG|200px|thumb|right|This is a [[sugar]] molecule. Carbon atoms are made blue, oxygen atoms are made red and hydrogen atoms are made white to show the difference. In reality atoms do not have a color.]] 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]].<ref>{{Cite book|url=https://goldbook.iupac.org/|title=The IUPAC Compendium of Chemical Terminology: The Gold Book|date=2019|publisher=International Union of Pure and Applied Chemistry (IUPAC)|editor-last=Gold|editor-first=Victor|edition=4|location=Research Triangle Park, NC|language=en|doi=10.1351/goldbook.m04002}}</ref> Molecules are made up of [[atom]]s 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.<ref>{{Cite book|url=https://www.worldcat.org/oclc/47953855|title=Chemistry : the central science.|date=2002|publisher=Prentice Hall|others=Theodore L. Brown, Theodore L. Brown|isbn=0-13-066997-0|edition=9th|location=Upper Saddle River, NJ|oclc=47953855}}</ref> In the [[w:Kinetic theory of gases|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.<ref>{{cite book| last= Chandra| first= Sulekh| title= Comprehensive Inorganic Chemistry| date= 2005| publisher= New Age Publishers| isbn= 81-224-1512-1}}</ref> In [[gas]]es like [[air]], the molecules are just flying around. In [[liquid]]s like [[water]], the molecules are stuck together but they can still move. In [[solid]]s like [[s