What is Chromium?
{{Distinguish|Chromium (web browser)}}[[File:Chromium.jpg|thumb|Chromium metal]] '''Chromium''' is a [[chemical element]]. Its symbol on the [[periodic table]] (a list of all the elements) is '''Cr'''. It always has 24 [[proton]]s, so its [[atomic number]] is 24. Its [[mass number]] (number of protons and neutrons) is about 54. Most of the times it has 28 [[neutron]]s, but different [[isotope]]s have more or fewer neutrons. As a metal, it has 24 [[electron]]s. Its [[ion]]s have fewer electrons. ==Properties== Chromium is a shiny [[metal]]. It is reactive, but it reacts with air to produce a very thin coating of [[chromium(III) oxide]], which prevents it from [[rust]]ing any more. ==Compounds== Chromium occurs in several [[oxidation state]]s; +2, +3, and +6 are most common. It forms [[chemical compound]]s that are colorful. *[[Chromium(II) oxide]], black, rare, [[reducing agent]] *[[Chromium(II) chloride]], blue when dissolved in water, unstable *[[Chromium(III) oxide]], dark green *[[Chromium(III) chloride]], green when containing water (hydrated), purple when not containing water (anhydrous) *[[Chromium(III) sulfate]] *[[Chromium(IV) oxide]], black, used in [[Audio cassette|cassettes]] *[[Chromium(VI) oxide]], chromium trioxide, red, [[oxidizing agent]], toxic. [[Chromic acid]] is formed by dissolving chromium(VI) oxide in water. *[[Chromyl chloride]], red liquid *[[Chrome alum]] [[File:Chromium(III)-oxide-sample.jpg|thumb|[[Chromium(III) oxide|Trivalent chromium compound]]]] ===Trivalent chromium=== There are two main types of chromium ions, which are found in chromium compounds. One type of chromium ion (''Cr<sup>[[oxidation state|3+]]</sup>'', trivalent chromium ) is required by our body and by those of other animals. If we do not get enough chromium, certain parts of our body may not work properly. We get most of the chromium we need from our food we eat. Chromium is also put into vitamins to make sure that we get enough. If we get too much of this type of chromium, it can harm our body. [[File:Chrom(VI