At room temperature, the density of chromium is 7.19 grams per cubic centimeters, chromium is a solid, and it is a grayish color. When it is not bonded to other atoms, chromium is brittle. As it is a transition metal, it is neither malleable nor ductile. Chromium is a poor conductor of heat and electricity; its thermal conductivity is 93.9, and its electrical resistivity is 125. Since it is a metal, it is able to conduct heat and electricity, but chromium is far less conductive than metals like copper and silver. Chromium is lustrous and has a high polish. The melting point of chromium is 1,907 degrees in Celsius, and the boiling point of chromium is 2,672 degrees in Celsius. Since it is a transition metal, chromium is a reactive element; it reacts with some acids, some metals, and halogens, like chlorine, fluorine, and bromine. However, chromium is less reactive than some other metals, like iron. This makes it is more resistant to corrosion than most metals. Chromium atoms tend to bond with other atoms through both ionic bonding, as do other metals. In ionic bonding, chromium bonds with another element through a difference in electric charges. If chromium gives up at least one electron to another element, chromium will become a positive ion and the other element will become a negative ion. Chromium will then bond with the other element since they have opposite charges. If chromium takes in at least one electron from another element, the reverse of this will happen. Some ionic-bonded chromium compounds include beryllium chromate, calcium chromate, zinc chromate, iron chromate, magnesium chromate, and barium chromate. Chromium has a total of six valence electrons, which are electrons that are free to change position in bonding with other atoms.
Compounds that chromium is commonly found in:
Compounds that chromium is commonly found in:
- Chromite:
- made up of one iron atom, two chromium atom, and four oxygen atoms
- the only mineral ore of chromium
- a dark gray color
- has some luster
- found in some igneous rock and rock
- Chromium Oxide:
- Chromium(II) Oxide:
- made up of one chromium atom and one oxygen atom
- electric charge of positive two
- electrons must be lost to an oxidizing agent for the compound to be formed
- can form chromium(III) oxide when more oxygen is added
- can be formed from chromium(III) oxide through chemical process
- black, powdery substance
- Chromium(III) Oxide:
- made up of two chromium atoms and three oxygen atoms
- forms a green pigment
- inorganic; found in nature as the mineral eskolaite
- density is 5.21 grams per cubic centimeters
- Chromium(IV) Oxide:
- made up of one chromium atom and two oxygen atoms
- inorganic
- used in magnetic tape recording devices before more modern film devices
- Chromium(VI) Oxide:
- made up of one chromium atom and five oxygen atoms
- very toxic; carcinogenic
- Chromium(II) Oxide:
- Chromate Salts:
- made up of compounds with one chromium atom and four oxygen atoms with a negative charge of two
- Dichromate Salts:
- made up of compounds with two chromium atoms and seven oxygen atoms with a negative charge of two
- Chromic Acid:
- made up of two hydrogen atoms, one chromium atom, and four oxygen atoms
- can be used to clean glass