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Periodic Table of Elements

Element Chromium - Cr

Comprehensive data on the chemical element Chromium is provided on this page; including scores of properties, element names in many languages, most known nuclides of Chromium. Common chemical compounds are also provided for many elements. In addition technical terms are linked to their definitions and the menu contains links to related articles that are a great aid in one's studies.

Chromium Menu

• Chromium Page One
  • Overview of Chromium
  • Chromium's Name in Other Languages
  • Atomic Structure of Chromium
  • Chemical Properties of Chromium
  • Physical Properties of Chromium
  • Regulatory / Health
  • Who/When/Where/How
• Chromium Page Two
  • Nuclides / Isotopes
  • Potential Parent Nuclides
• Chromium Page Three
  • Common Chemical Compounds of Chromium

Overview of Chromium

• Atomic Number: 24
• Group: 6
• Period: 4
• Series: Transition Metals

Chromium's Name in Other Languages

• Latin: Chromium
• Czech: Chrom
• Croatian: Krom
• French: Chrome
• German: Chrom - r
• Italian: Cromo
• Norwegian: Krom
• Portuguese: Crômio
• Russian: Хром
• Spanish: Cromo
• Swedish: Krom

Atomic Structure of Chromium

• Atomic Radius: 1.85Å
• Atomic Volume: 7.23cm³/mol
• Covalent Radius: 1.18Å
• Cross Section (Thermal Neutron Capture)σ_a/barns: 3.1
• Crystal Structure: Cubic body centered

  

• Electron Configuration:

  1s² 2s²p⁶ 3s²p⁶d⁵ 4s¹

• Electrons per Energy Level: 2,8,13,1

  Shell Model
  

• Ionic Radius: 0.52Å
• Filling Orbital: 3d⁵
• Number of Electrons (with no charge): 24
• Number of Neutrons (most common/stable nuclide): 28
• Number of Protons: 24
• Oxidation States: 6,3,2
• Valence Electrons: 3d⁵ 4s¹

  Electron Dot Model
  

Chemical Properties of Chromium

• Electrochemical Equivalent: 0.32333g/amp-hr
• Electron Work Function: 4.5eV
• Electronegativity: 1.66 (Pauling); 1.56 (Allrod Rochow)
• Heat of Fusion: 16.9kJ/mol
• Incompatibilities:

  Strong oxidizers (such as hydrogen peroxide), alkalis

• Ionization Potential
  • First: 6.766
  • Second: 16.5
  • Third: 30.96
• Valence Electron Potential (-eV): 170

Physical Properties of Chromium

• Atomic Mass Average: 51.9961
• Boiling Point: 2945K 2672°C 4842°F
• Coefficient of lineal thermal expansion/K^-1: 6.2E^-6
• Conductivity

  Electrical: 0.0774 10⁶/cm Ω
  Thermal: 0.937 W/cmK

• Density: 7.19g/cc @ 300K
• Description:

  Hard brittle gray transition metal.

• Elastic Modulus:
  • Bulk: 160.2/GPa
  • Rigidity: 115.3/GPa
  • Youngs: 279/GPa
• Enthalpy of Atomization: 397.5 kJ/mole @ 25°C
• Enthalpy of Fusion: 15.31 kJ/mole
• Enthalpy of Vaporization: 348.8 kJ/mole
• Flammablity Class: Non-combustible solid (except as dust)
• Freezing Point: see melting point
• Hardness Scale
  • Brinell: 1120 MN m^-2
  • Mohs: 8.5
  • Vickers: 1060 MN m^-2
• Heat of Vaporization: 344.3kJ/mol
• Melting Point: 2130K 1857°C 3375°F
• Molar Volume: 7.78 cm³/mole
• Physical State (at 20°C & 1atm): Solid
• Specific Heat: 0.45J/gK
• Vapor Pressure = 990Pa@1857°C

Regulatory / Health

• CAS Number
  • 7440-47-3
• RTECS: GB4200000
• OSHA Permissible Exposure Limit (PEL)
  • TWA: 1 mg/m³
  • Notes: The PEL also applies to insoluble chromium salts.
• OSHA PEL Vacated 1989
  • TWA: 1 mg/m³
  • Notes: The PEL also applies to insoluble chromium salts.
• NIOSH Recommended Exposure Limit (REL)
  • TWA: 0.5 mg/m³
  • IDLH: 250 mg/m³
• Routes of Exposure: Inhalation; Ingestion; Skin and/or eye contact
• Target Organs: Eyes, skin, respiratory system
• Levels In Humans:
  Note: this data represents naturally occuring levels of elements in the typical human, it DOES NOT represent recommended daily allowances.
  • Blood/mg dm^-3: 0.006-0.11
  • Bone/p.p.m: 0.1-033
  • Liver/p.p.m: 0.02-3.3
  • Muscle/p.p.m: 0.024-0.84
  • Daily Dietary Intake: 0.01-1.2 mg
  • Total Mass In Avg. 70kg human: 14 mg

Who / Where / When / How

• Discoverer: Nicholas Louis Vauquelin
• Discovery Location: Paris France
• Discovery Year: 1797
• Name Origin:

  Greek: chrôma (color).

• Abundance of Chromium:
  • Earth's Crust/p.p.m.: 100
  • Seawater/p.p.m.:
    • Atlantic Suface: 0.00018
    • Atlantic Deep: 0.00023
    • Pacific Surface: 0.00015
    • Pacific Deep: 0.00025
  • Atmosphere/p.p.m.: N/A
  • Sun (Relative to H=1E¹²): 513000
• Sources of Chromium:

  Does not occur free in nature. Chromite [Fe,Mg(CrO₄)] is its most important mineral. Annual world wide production around 20,000 tons. Primary mining sources are Turkey, South Africa, Zimbabwe, Russia and Philippines.

• Uses of Chromium:

  Used to make stainless steel. Also used in plating for car parts, tools, knives, camouflage paint, stereos, video tapes and lasers. It gives rubies and emeralds their color.

• Additional Notes:

Chromium Menu

• Chromium Page One
  • Overview of Chromium
  • Chromium's Name in Other Languages
  • Atomic Structure of Chromium
  • Chemical Properties of Chromium
  • Physical Properties of Chromium
  • Regulatory / Health
  • Who/When/Where/How
• Chromium Page Two
  • Nuclides / Isotopes
  • Potential Parent Nuclides
• Chromium Page Three
  • Common Chemical Compounds of Chromium

References

A list of reference sources used to compile the data provided on our periodic table of elements can be found on the main periodic table page.

Related Resources

• Anatomy of the Atom
  Answers many questions regarding the structure of atoms.
• Molarity, Molality and Normality
  Introduces stoichiometry and explains the differences between molarity, molality and normality.
• Molar Mass Calculations and Javascript Calculator
  Molar mass calculations are explained and there is a JavaScript calculator to aid calculations.
• Chemical Database
  This database focuses on the most common chemical compounds used in the home and industry.

Citing this page

If you need to cite this page, you can copy this text:

Kenneth Barbalace. Periodic Table of Elements - Chromium - Cr. EnvironmentalChemistry.com. 1995 - 2024. Accessed on-line: 11/21/2024
https://EnvironmentalChemistry.com/yogi/periodic/Cr.html
.