What is Chromium?
Chromium is a hard metal with a distinct luster and brittleness. It is silvery-gray, does not tarnish when exposed to air. It burns when heated and forms green chromic oxide. It can be polished. It is unstable with oxygen. Once it is exposed to oxygen, it produces a thin layer of oxide and it’s impermeable to oxygen, which protects the below metal.
Where is Chromium obtained?
The Earth’s crust contains about 100 to 300 parts per million of chromium. Chromium does not occur as a free element. The majority of chromium is produced from chrome iron ore or chromite. South Africa is the main producer of chromite and is followed by India, Turkey, Kazakhstan, Brazil, Albania, Iran, Philippines, New Zealand, and Finland. Every year, around 20,000 tons of chromium are produced.
History of Chromium
It was in 1797 when a French chemist, Louis-Nicolas Vauquelin discovered chromium in the mineral Siberian red lead. The uniqueness of this mineral has caught his attention and convinced him that the distinct characteristic of this mineral is because of its undiscovered metal, and he later found out that he’s right. He was able to isolate chromium by heating charcoal with chromium trioxide.
The end result was tiny needles of pure chromium. He combined chromium with other solutions and was able to produce a number of vibrant compounds. It has the tendency to create vivid colors when combined with other materials, thus, the name “chroma,” which is a Greek word for “color.”
Classification, Properties and Characteristics of Chromium
Chromium is a chemical element known for its ability to produce vibrant colors. It is a lustrous metal, malleable, tasteless, and odorless. It forms a thin protective oxide coating when exposed to air. If you heat chromium, it forms green chromium oxide. Chromium has the ability to resist rust, which makes chromium a great element for electroplating.
Lewis Dot Structure of Chromium
Bohr’s Atomic Model of Chromium
Atomic Data of Chromium
Physical Properties of Chromium
| Color | Silvery with a blue tinge |
| Odor | Odorless |
| Taste | Tasteless |
| Atomic Mass | 51.996 |
| Weight | 51.996 |
| Density | 7.15 |
| Atomic Radius | 140 pm |
| Ionization Energy | 6.767 eV |
| Covalent Radius | 139 |
| Ionic Radius | 0.061 nm (+3) ; 0.044 nm (+6) |
| Electronic Gain Enthalpy | 652.87kJ mol‑1 |
| Electron Negativity | 1.6 |
| Electron Affinity | 64.3 kJ mol‑1 |
| Melting Point | 1907°C, 3465°F, 2180 K |
| Boiling Point | 2671°C, 4840°F, 2944 K |
Chemical Properties of Chromium
| Atomic Number | 24 |
| Group | 6 |
| Period | 4 |
| Block | d |
| Electronic Configuration | [Ar] 3d54s1 |
| Combustion | It does not burn itself, but flammable in powder form |
| Chemical Reactivity | It does not react with water but reactive with acids |
| Valency of Element | 1 |
Different States of Chromium
As a transition metal, chromium is solid at room temperature. It can exist in various chemical forms, such as chromium (III), chromium (0), and chromium (VI), which is also known as hexavalent chromium. A particular form of chromium integral to human health is trivalent chromium (chromium III).
What are the common uses of Chromium?
Chromium is useful in various applications, such as the following:
- It is used in alloys and stainless steel.
- Chromium is used for electroplating, such as on bicycles and cars, because it produces a smooth silver finish. Not to mention, it is resistant to corrosion.
- Chromium is used as a catalyst in various chemical reactions.
- Chromium compounds are known for their vivid colors, such as red, yellow, orange, and green.
- New alloys are formed with the use of chromium. It is mixed with other elements such as aluminum and stainless steel.
- Expensive gems like emerald have a small amount of chromium. It is usually found in the crystal lattice structure of gems.
- Chromium is present in paints and dyes as well as chemical makeup used for making fabrics.
- Chromium is used in the automotive industry, such as in rims and wheels. They are chromed to spruce up the physical components of the car. Aside from improving the look of the vehicle, it also acts as a protective oxide layer on the surface to resist corrosion.
- Stainless steel has chromium in it. It is an alloy of iron and a bit of chromium, making stainless steel resistant to corrosion.
- Chromium is used in various kitchen equipment and appliances because of its ability to resist corrosion. Examples are skillets and stainless steel pans.
- Chromium is used to tan leather products. An animal’s skin is chromed using chromium sulfate, turning it into leather. It does not only improve the appearance of leather but also makes it resistant to hot water.
- Furnaces and kilns use bricks consisting of chromite ore to retain durability and withstand high temperatures.
- Chromium ions are used in the textile sector to help dyes stick to the fabric.
Price of Chromium
The cost of chromium is dependent on supply and demand. The cost of pure chromium is $32 per 100 grams. If you purchase in bulk, the cost is much cheaper, but is dependent on the supplier and market demand.
Interesting facts about Chromium
- Don’t you know that chromium has long been used by ancient Chinese?
- Don’t you know that around 80% of produced chromium yearly is sued to produce metal alloy?
- The name chromium is derived from “chroma”, Greek word for color. It is called that way because of chromium’s ability to produce colorful compounds.
- About 99% of the world’s supply of chromite comes from Zimbabwe and Southern Africa. It consists of iron oxide and chromium oxide.
- The toxic form of chromium, hexavalent chromium is carcinogenic. It is detrimental to health because it can destroy red blood cells leading to genetic mutations.
- Trivalent chromium has biological use. It acts as a micronutrient and helps boosts the functions of insulin in people suffering from glucose intolerance.
Frequently Asked Questions
Q1. What elements does chromium react with?
Chromium is highly reactive with other elements specially chlorine, fluorine, iodine, and bromine. Once chromium gets in contact with these elements in the halogen group it forms colorful compounds. It dissolves with sulphuric acid and hydrochloric acid thereby creating solutions that have chromium ion.
Q2. What can destroy chromium?
Hexavalent chromium is difficult to destroy. To get rid of it, it needs to be removed physically through the process of soil excavation or pumping and treating groundwater to stabilize it within the environment’s surface.
Q3. Is chromium reactive with water?
At room temperature, elementary chromium doesn’t react with water. The majority of chromium compounds are insoluble in water because they are bound to float particles in water. The only water soluble compounds are chromium hydroxide and chromium oxide.
Q4. Is chromium toxic to humans?
The danger associated with exposure to chromium has something to do with its oxidation state. Chromium in metal form has a low toxicity level. However, chromium in hexavalent form can be extremely poisonous. It can cause a wide array of symptoms such as allergic skin reactions, dermatitis, and ulcerations.
References
- https://www.rsc.org/periodic-table/element/24/chromium
- https://www.britannica.com/science/chromium
- https://www.lenntech.com/periodic/elements/cr.htm
- https://pubchem.ncbi.nlm.nih.gov/element/Chromium#section=Electron-Configuration
- https://www.chemicool.com/elements/chromium.html
- https://byjus.com/chemistry/chromium/
- https://chemistrytalk.org/chromium-element/
- https://www.atsdr.cdc.gov/csem/chromium/what_is_chromium.html
- http://www.chemistryexplained.com/elements/A-C/Chromium.html
- https://www.livescience.com/29194-chromium.html