Chromium Facts

Chemical & Physical Properties of Chromium

These are crystals of pure elemental chromium metal and a one cubic centimeter cube of chromium.
These are crystals of pure elemental chromium metal and a one cubic centimeter cube of chromium. Alchemist-hp

Chromium is element atomic number 24 with element symbol Cr. Here are facts about the metal and its atomic data.

Chromium Basic Facts

Chromium Atomic Number: 24

Chromium Symbol: Cr

Chromium Atomic Weight: 51.9961

Chromium Discovery: Louis Vauquelin 1797 (France)

Chromium Electron Configuration: [Ar] 4s1 3d5

Chromium Word Origin: Greek chroma: color

Chromium Properties: Chromium has a melting point of 1857+/-20°C, boiling point of 2672°C, specific gravity of 7.18 to 7.20 (20°C), with valences usually 2, 3, or 6.

The metal is a lustrous steel-gray color which takes a high polish. It is hard and resistant to corrosion. Chromium has a high melting point, stable crystalline structure, and moderate thermal expansion. All chromium compounds are colored. Chromium compounds are toxic.

Uses: Chromium is used to harden steel. It is a component of stainless steel and many other alloys. The metal is commonly used for plating to produce a shiny, hard surface that is resistant to corrosion. Chromium is used as a catalyst. It is added to glass to produce an emerald green color. Chromium compounds are important as pigments, mordants, and oxidizing agents.

Sources: The principal ore of chromium is chromite (FeCr2O4). The metal may be produced by reducing its oxide with aluminum.

Element Classification: Transition Metal

Chromium Physical Data

Density (g/cc): 7.18

Melting Point (K): 2130

Boiling Point (K): 2945

Appearance: very hard, crystalline, steel-grayish metal

Atomic Radius (pm): 130

Atomic Volume (cc/mol): 7.23

Covalent Radius (pm): 118

Ionic Radius: 52 (+6e) 63 (+3e)

Specific Heat (@20°C J/g mol): 0.488

Fusion Heat (kJ/mol): 21

Evaporation Heat (kJ/mol): 342

Debye Temperature (K): 460.00

Pauling Negativity Number: 1.66

First Ionizing Energy (kJ/mol): 652.4

Oxidation States: 6, 3, 2, 0

Lattice Structure: Body-Centered Cubic

Lattice Constant (Å): 2.880

CAS Registry Number: 7440-47-3

References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)

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Helmenstine, Anne Marie, Ph.D. "Chromium Facts." ThoughtCo, Jun. 18, 2017, Helmenstine, Anne Marie, Ph.D. (2017, June 18). Chromium Facts. Retrieved from Helmenstine, Anne Marie, Ph.D. "Chromium Facts." ThoughtCo. (accessed December 13, 2017).