What is Sodium?
{{Infobox sodium}} [[File:Sodium.jpg|thumb|Sodium pellets in a container]] '''Sodium''' is a [[chemical element]] with an [[atomic number]] of 11. Its symbol is '''Na''' (from its Latin name ''natrium''). It is an [[alkali metal]]. Although sodium has many [[isotope]]s, most decay in a short time. Because of this, all sodium in nature (mainly found in [[seawater]]) is of the isotope <sub>11</sub>Na<sup>23</sup>. The [[atomic mass]] of sodium is 22.9898. == Properties == Sodium is a light-weight, [[silver]]-colored [[metal]]. Sodium is soft. It can easily be cut with a knife. When someone cuts it, the exposed part will become white over time. It reacts with air to form, at first [[sodium oxide]], then slowly [[sodium hydroxide]] and [[sodium carbonate]]. Sodium is a little less [[Density|dense]] than water. It floats and reacts instantly with water, producing [[hydrogen]] and [[sodium hydroxide]]. This reaction makes a lot of heat, usually causing the hydrogen to light on fire. When this happens, sodium melts because of its low melting point. Sodium is highly reactive because it has one [[valence electron]], which is easily removed. Compared with other [[Alkali metal|alkali metals]], sodium is less reactive than [[potassium]] and more reactive than [[lithium]].<ref>{{cite web|author=De Leon, N.|title=Reactivity of Alkali Metals|url=http://www.iun.edu/~cpanhd/C101webnotes/modern-atomic-theory/alkali-reac.html|publisher=[[Indiana University Northwest]]|accessdate=2007-12-07|archive-date=2018-10-16|archive-url=https://web.archive.org/web/20181016113143/http://www.iun.edu/~cpanhd/C101webnotes/modern-atomic-theory/alkali-reac.html|url-status=dead}}</ref> == Chemical compounds == These are [[chemical compound]]s that contain sodium [[ion]]s. Sodium only exists in one [[oxidation state]]: +1. *[[Sodium aluminum fluoride]], used to make aluminum *[[Sodium amide]], very strong base *[[Sodium arsenite]], colorless solid, very toxic *[[Sodium arsenate]], oxidizing agent, very toxic *[[Sodium azide]], used in airbags *[