Chromium

Chromium is an element discovered by Louis-Nicholas Vauquelin in 1797 while experimenting with Siberian red lead. It is a metallic atom that is acquired in mineral form in trace amounts.

Properties


Chromium is a transition metal which has the atomic number 24.(Wilbraham, p268). Its electronic configuration is 4s13d5, and has low energy. The most common forms of Chromium are: chromium 0, chromium III, and chromium VI.  The compounds do not have taste or color. It has a wide range of oxidation states, but the most common states are +2, +3, and +6. +3 is the most stable.  Oxygen is what oxydizes chromium, which forms a thin protective oxide surface layer with another element.  This forms a spinal structure which prevents diffusion of oxygen into the underlying layer.  Chromium does not suffer hydrogen embrittlement, which is when a metal cracks when it is exposed to hydrogen. Chromium can get nitrogen embrittlement though. 

Occurrences
Chromium is mined as chromite ore. Chromium is not found freely in nature. Most ores consist of the mineral chromite. Commercially, Chromium is obtained by heating the ore in the presence of aluminium or silicon. Around two-fifths of chromite ore is produced in South Africa. Other producers are India, Russia, Kazakhstan, and Turkey. In Russia, the udachnaya Mine produces native chromium. It is often found in soil and groundwater at abandoned industrial sites. 

Chromium usually occurs in the environment as trivalent chromium (Cr III), which is natural, and metallic chromium (Cr 0), which is produced industrially. 

Uses
Chromium's most well known use is for chrome or chrome plating. Some other uses of chromium is making or is an ingredient in making: stainless steel, chrome plating, anodized aluminium, turning the surface of aluminium into ruby and producing synthetic rubies because chromium is what makes a ruby red, yellow paint, catalysts, gasoline, chemical reagent, high-temperature electrical conductors, chromium bromide, dietary supplement, and tanning leather. 



In the category of how it is used in food, the best source of chromium is brewer's yeast. But since most people don't like to eat it because it causes abdominal distention, other good sources are: liver, beef, oysters, chicken, apples, spinach, and green peppers to name a few. Chromium stimulates fatty acid and cholesterol synthesis.  It is said that chromium can be used as a weight loss agent and an athletic supplement to increasing lean body mass, also that chromium supplements can help in controling type 2 diabetes, but the evidence has not been consistant. 

Health Hazards
Some forms of chromium are a danger to health. People are usually exposed to chromium through breathing, drinking, eating, or skin contact. One of these would be chromium VI. It is a poisonous compound that can cause problems if ingested of inhaled. If this is done, there could be irritation of the eyes or skin, ulcers, respiratory problems, kidney damage, lung cancer, liver damage, and even death.  A lethal dosage of chromium is half a teaspoon. Because of the danger, the World Health Organization recomends that the max concentration of chromium in water is .05 milligrams per liter. Metal chromium and chromium III compounds aren't usually considered as a danger to health.  The average daily intake from air, water, and food is estimated to be less than 0.2 to 0.4 micrograms.