Chromium is the first element in the sixth column of the periodic table. It is classified as a transition metal. Chromium atoms have 24 electrons and 24 protons with the most abundant isotope having 28 neutrons.
Characteristics and Properties
Under standard conditions chromium is a hard silvery metal with a bluish tint. When it is exposed to air a thin layer of chromium oxide forms over the surface which protects the metal from further reaction with the air. Chromium can be polished to achieve a shiny mirror-like finish that is resistant to corrosion.
For a metal, chromium is fairly active and will react with many other metals as well as with oxygen. It will not react with water.
Chromium is known for its many colorful compounds. These include chromium(III) oxide (green), lead chromate (yellow), anhydrous chromium(III) chloride (purple), and chromium trioxide (red).
Where is chromium found on Earth?
Chromium is only found rarely as a free element in nature. It is mostly found in ores scattered throughout the Earth's crust where it is about the twenty-fourth most abundant element. The main ore that is mined for the production of chromium is cromite.
How is chromium used today?
Chromium is often mixed with other metals to make alloys. One of the most important chromium alloys is produced when chromium is mixed with steel to make stainless steel. Stainless steel is strong and resistant to corrosion. Chromium is also used to produce superalloys with nickel that are used in jet engines.
Another popular application for chromium is as a shiny silver coating on metallic surfaces. It also provides corrosion protection.
Because chromium compounds come in such a variety of colors, it has also been used as a pigment in paints. One of the most popular colors made from chrome is yellow. Many school busses are painted in chrome yellow.
Other applications for chromium include wood preservatives, tanning, as catalysts in industrial production, and magnets.
How was it discovered?
Chromium was discovered by French chemist Nicolas L. Vauquelin in 1797. He later isolated the element and gave it its name.
Where did chromium get its name?
Chromium gets its name from the Greek word "chroma" meaning color. This name was chosen because the element can form so many different colored compounds.
Isotopes
Chromium has four stable isotopes that occur in nature including 50Cr, 52Cr, 53Cr, and 54Cr with the majority of the chromium found in nature being 52Cr.
Interesting Facts about Chromium
Rubies get their red color from small traces of chromium.
The Qin Dynasty of Ancient China used chromium oxide to coat and protect their weapons.
About half of all chromite ore is currently produced in southern Africa. Other big producers include Turkey and India.
