What is Chromium? | Types, Definition, Structure, Function & Facts
What is Chromium?
Chromium is the first element in the sixth column of the periodic table. It is classified as a transition metal. The chromium atom has 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 exposed to air, a thin layer of chromium oxide forms on the surface, which protects the metal from further reaction with air. Chrome can be polished to a mirror-like shine, resistant to corrosion.
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For one metal, chromium is quite active and will react with many other metals as well as oxygen. It will not react with water.
Chromium is known for many color compounds. These include chromium(III) oxide (green), lead chromate (yellow), anhydrous chromium(III) chloride (purple), and chromium trioxide (red).
Highlights of Chromium:
| Symbol | Cr |
| Atomic Number | 24 |
| Atomic Weight | 51.996 |
| Classification | Transition metal |
| Phase at Room Temperature | Solid |
| Density | 7.19 grams per cm cubed |
| Melting Point | 1907°C, 3465°F |
| Boiling Point | 2671°C, 4840°F |
| Discovered by | N.L. Vauquelin in 1797 |
Where is Chromium found on Earth?
Chromium is rarely found as a free element in nature. It is mainly found in minerals scattered throughout the earth’s crust, where it is the twenty-fourth most abundant element. The main ore mined to produce chromium is chromite.
How is Chromium used today?
Chromium is often mixed with other metals to form alloys. One of the most important chromium alloys is created when chromium is mixed with steel to make stainless steel. Stainless steel is strong and corrosion resistant. Chromium is also used to produce superalloys with nickel used in jet engines.
Another common application of chromium is as a shiny silver coating on metal surfaces. It also provides corrosion protection.
Because chromium compounds come in a variety of colors, it is also used as a pigment in paints. One of the most popular chrome-based colors is yellow. Many school buses are painted chrome yellow.
Other uses of chromium include wood preservatives, leather tanning, industrial catalysts, and magnets.
How was it discovered?
Chromium was discovered in 1797 by the French chemist Nicolas L. Vauquelin. He later isolated the element and gave it a name.
Where did Chromium get its name?
Chromium gets its name from the Greek word “chroma” which means color. This name was chosen because the element can form many different colored compounds.
Isotopes
Chromium contains four naturally occurring stable isotopes including 50Cr, 52Cr, 53Cr and 54Cr, with the majority of naturally occurring chromium being 52Cr.
Interesting Facts about Chromium
Rubies get their red color from a small amount of chromium.
Ancient China’s Qin Dynasty used chromium oxide to coat and protect their weapons.
About half of chromite ore is currently produced in South Africa. Other major producers are Türkiye and India.
Some chromium compounds are considered toxic.