Chromium is discovered in the facility of the regular table, a chart the shows just how chemical facets are regarded each other. Elements in teams 3 through 12 are known as the transition metals. These elements all have comparable physical and also chemical properties. They have actually a bright, shiny surface and high melt points.

Chromium was found in 1797 by French chemist Louis-Nicolas Vauquelin (1763-1829). The name comes from the Greek indigenous chroma, an interpretation "color," due to the fact that chromium link are numerous different colors.

about three-quarters the chromium produced today is used in alloys, consisting of stainless steel. An alloy is make by melting and mixing two or more metals. The mixture has various properties 보다 the individual metals. Chromium is likewise used come cover the surface of various other metals. This an approach protects the basic metal and also gives the surface ar a bright, glowing appearance in ~ a short cost.

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symbol Cr

atomic NUMBER 24

atom MASS 51.996

household team 6 (VIB) shift metal

together CRO-mee-um

Discovery and naming

Chromium was found in a mineral recognized as Siberian red lead. The mineral was very first described in 1766 through German mineralogist Johann Gottlob Lehmann (1719-67). Scientists were puzzled about what facets this brand-new mineral contained. It had actually a type and a shade not watched in other minerals. In part cases, it was found, as part said, "attached like small rubies to quartz."

studies of Siberian red lead to be difficult, however. It was mined at just one ar in Germany and miners discovered it daunting to remove. Scientists had actually only little amounts of the mineral to study. Lock guessed that it included command and arsenic, molybdenum, or some various other metal.

In 1797, Vauquelin began his very own studies of Siberian red lead. He was persuaded that the mineral consisted of a brand-new element. Nobody of the aspects then known could account because that his results. He report "a new metal, own properties completely unlike those of any kind of other metal."

A year later, Vauquelin had the ability to isolate a little sample that the steel itself. That heated charcoal (nearly pure carbon ) with a compound of chromium, chromium trioxide (Cr 2 O 3 ). As soon as the reaction to be complete, he found tiny metallic needles that chromium metal:

The name chromium was suggested by 2 French chemists, Antoine Francois de Fourcroy (1755-1809) and also René-Just Haüy (1743-1822), due to the fact that chromium forms so numerous different colored compounds. The colors selection from purple and also black to green, orange, and also yellow.

physical properties

Chromium is a hard, steel-gray, shiny, steel that division easily. It has actually a melting suggest of 1,900°C (3,450°F) and a boiling allude of 2,642°C (4,788°F). The thickness is 7.1 grams every cubic centimeter. One necessary property is that chromium have the right to be refined to a high shine.

chemical properties

Chromium is a fairly active metal. That does not react with water, yet reacts with many acids. The combines v oxygen at room temperature to type chromium oxide (Cr 2 O 3 ). Chromium oxide creates a thin layer ~ above the surface of the metal, protecting it from more corrosion (rusting).

event in nature

The diversity of chromium in the Earth's crust is about 100 come 300 components per million. The ranks about number 20 amongst the chemical elements in terms of their diversity in the earth.

Chromium does not occur as a cost-free element. Today, practically all chromium is produced from chromite, or chrome stole ore (FeCr 2 O 4 ).

The leading producer the chromite ore is southern Africa. Other essential producers are Kazakhstan, Turkey, India, Finland, Albania, and also Brazil. There space no chromite mines in the united States.


over there are 4 naturally developing isotopes of chromium: chromium-50, chromium-52, chromium-53, and chromium-54. Isotopes are two or an ext forms of one element. Isotopes differ native each other according to their mass number. The number composed to the appropriate of the element's name is the fixed number. The mass number represents the variety of protons plus neutrons in the nucleus of one atom the the element. The variety of protons identify the element, yet the number of neutrons in the atom of any kind of one element can vary. Each variation is one isotope.

7 radioactive isotope of chromium are known also. A radiation isotope is one that division apart and gives off some type of radiation. Radioactive isotope are produced when very small particles room fired in ~ atoms. This particles stick in the atoms and also make castle radioactive.

Chromium compounds' colors range from purple and black to green, orange, and yellow.

One radiation isotope the chromium is supplied in clinical research, chromium-51. This isotope is provided as a tracer in researches on blood. A tracer is a radiation isotope whose visibility in a mechanism can conveniently be detected. The isotope is injected right into the mechanism at part point. Within the system, the isotope gives off radiation. That radiation deserve to be complied with by means of detectors placed approximately the system.

A common use of chromium-51 is in researches of red blood cells. The isotope can be provided to uncover out how many blood cells are present in a person's body. It have the right to be used to measure just how long the blood cells endure in the body. The isotope can additionally be supplied to study the flow of blood into and also out of a fetus (an unborn child).


The methods for producing chromium are similar to those provided for other metals. One method is to warmth chromium oxide (Cr 2 O 3 ) with charcoal or aluminum. The charcoal (nearly pure carbon) or aluminum bring away oxygen indigenous the chromium oxide, leaving pure chromium metal. This technique is comparable to the one supplied by Vauquelin:

Chromium can likewise be derived by pass an electric existing through that is compounds:

occasionally chromite is converted straight to one alloy recognized as ferrochromium (or ferrochrome):

Ferrochromium is vital chromium alloy. The is used to include chromium come steel. As soon as steel is first made, the is a really hot, fluid material. To do chromium steel, ferrochromium is included to the hot liquid steel. There, the chromium dissolves into the hot steel. Once the molten stole hardens, the chromium is trapped inside. The is now chromium steel.

The radioactive isotope chromium-51 is used to research the flow of blood into and also out of a fetus (an unborn child).


about 87 percent that chromium used in the United states goes right into alloys. The addition of chromium provides the last product more difficult and more resistant come corrosion. Around 70 percent of all chromium is supplied in the production of stainless steel. The applications of stainless stole are nearly endless. They incorporate automobile and truck bodies, plating for boats and ships, building and construction parts for buildings and also bridges, components for chemical and petroleum equipment, electric cables, maker parts, eating and also cooking utensils, and also reinforcing products in tires and also other materials.

2 other significant uses the chromium room electroplating and also the produce of refractory bricks. Electroplating is the process by i m sorry an electric existing is passed v a water equipment of a metallic compound. The current reasons the material to breakdown into two parts, together the adhering to reaction shows:

The totally free chromium developed in this reaction is laid down in a slim layer ~ above the surface ar of another metal, such together steel. The chromium protects the steel from corrosion and gives that a bright, shining surface. Countless kitchen appliances room "chromeplated" this way.

part chromium is also used to do refractory bricks. A refractory material have the right to withstand really high temperature by reflecting heat. Refractory materials are supplied to heat high-temperature ovens.


Chromium compound have numerous different uses. Some include:

chromic fluoride (CrF 3 ): printing, dyeing, and also mothproofing woolen fabric

chromic oxide (Cr 2 O 3 ): a environment-friendly pigment (coloring agent) in paint, asphalt roofing, and also ceramic materials; refractory bricks; abrasive

chromic sulfate (Cr 2 (SO 4 ) 3 ): a eco-friendly pigment in paint, ceramics, glazes, varnishes, and inks; chrome plating

chromium boride (CrB): refractory; high-temperature electrical conductor

chromium dioxide (CrO 2 ): covering for magnetic tapes ("chromium" tapes)

chromium hexacarbonyl (Cr(CO) 6 ): catalyst; gasoline additive

Health effects

Chromium is an facet with 2 faces, as much as health impacts are concerned. Little amounts of chromium are important for the


Chromium originates from the Greek word because that color. In this bottles, the different shades represent assorted colors the chromium compounds.
health and wellness of plants and animals. In humans, a chromium deficiency leads to diabetes-like symptoms. Diabetes is a condition that creates when the body does not use sugar properly. Chromium appears to beat a role in helping the body usage sugar.

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The addition of chromium provides the last product harder and much more resistant to corrosion.

In larger amounts, chromium is harmful. Some compounds are specifically dangerous, bring about a decision or sores if spilled on the skin. They can additionally cause sores in the mouth and throat if inhaled. If swallowed, some chromium compounds have the right to seriously damage the throat, stomach, intestines, kidneys, and also circulatory (blood) system. Scientists believe exposure to some chromium compounds on a long-term basis causes cancer. Together a result, the U.S. Ecological Protection agency (EPA) has developed rules around the lot of chromium to which workers have the right to be exposed.