Chromium Tech Report
Overview
Chromium is found in the center of the periodic table, a chart that shows how chemical elements are related to each other. Elements in Groups 3 through 12 are known as the transition metals. These elements all have similar physical and chemical properties. They have a bright, shiny surface and high melting points.

Chromium was discovered in 1797 by French chemist Louis-Nicolas Vauquelin (1763-1829). The name comes from the Greek word chroma, meaning "color," because chromium compounds are many different colors.

About three-quarters of chromium produced today is used in alloys, including stainless steel. An alloy is made by melting and mixing two or more metals. The mixture has different properties than the individual metals. Chromium is also used to cover the surface of other metals. This technique protects the base metal and gives the surface a bright, shiny appearance at a low cost.

SYMBOL
Cr

ATOMIC NUMBER
24

ATOMIC MASS
51.996

FAMILY
Group 6 (VIB)
Transition metal

Physical properties
Chromium is a hard, steel-gray, shiny, metal that breaks easily. It has a melting point of 1,900°C (3,450°F) and a boiling point of 2,642°C (4,788°F). The density is 7.1 grams per cubic centimeter. One important property is that chromium can be polished to a high shine.

Chemical properties
Chromium is a fairly active metal. It does not react with water, but reacts with most acids. It combines with oxygen at room temperature to form chromium oxide (Cr2O3). Chromium oxide forms a thin layer on the surface of the metal, protecting it from further corrosion (rusting).