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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