Physical Properties of the Element Chromium

Chromium is element atomic number 24 with element symbol Cr.

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, a boiling point of 2672°C, a 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