Element Information, Facts, Properties, Trends, Uses, Comparison with other elements
Chromium is a chemical element with symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard and brittle metal which takes a high polish, resists tarnishing, and has a high melting point.
It belongs to group 6 of the periodic table having trivial name .
Read key information and facts about element Chromium
|Group in Periodic Table||6|
|Group Name||chromium family|
|Period in Periodic Table||period 4|
|Block in Periodic Table||d -block|
|Electronic Configuration||[Ar] 3d5 4s1|
|Electronic Shell Structure (Electrons per shell)||2, 8, 13, 1|
|Melting Point||2180 K|
|Boiling Point||2944 K|
How to Locate Chromium on Periodic Table
Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 24 to find Chromium on periodic table.
Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Chromium on periodic table look for cross section of group 6 and period 4 in the modern periodic table.
The element Chromium was discovered by N. Vauquelin in year 1797 in France. Chromium was first isolated by N. Vauquelin in 1798. Chromium derived its name from the Greek word chroma, meaning 'color'.
Vauquelin discovered the trioxide incrocoiteore, and later isolated the metal by heating the oxide in a charcoal oven.
Chromium Presence: Abundance in Nature and Around Us
The table below shows the abundance of Chromium in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.
|ppb by weight (1ppb =10^-7 %)||ppb by atoms (1ppb =10^-7 %)|
|Abundance in Universe||15000||400|
|Abundance in Sun||20000||400|
|Abundance in Meteorites||3100000||1200000|
|Abundance in Earth's Crust||140000||55000|
|Abundance in Oceans||0.6||0.071|
|Abundance in Humans||30||4|
Crystal Structure of Chromium
The solid state structure of Chromium is Body Centered Cubic.
The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.
Unit Cell Parameters
The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)
|291 pm||291 pm||291 pm|
and the angles between them Lattice Angles (alpha, beta and gamma).
The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.
The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.
|Space Group Name||Im_ 3m|
|Oxidation States||Space Group Number||229|
|Crystal Structure||Body Centered Cubic|
Chromium Atomic and Orbital Properties
Chromium atoms have 24 electrons and the electronic shell structure is [2, 8, 13, 1] with Atomic Term Symbol (Quantum Numbers) 7S3.
|Number of Electrons (with no charge)||24|
|Number of Protons||24|
|Number of Neutrons||28|
|Shell structure (Electrons per energy level)||2, 8, 13, 1|
|Electron Configuration||[Ar] 3d5 4s1|
|Valence Electrons||3d5 4s1|
|Main Oxidation States||2, 3, 6|
|Oxidation States||-4, -2, -1, 0, 1, 2, 3, 4, 5, 6|
|Atomic Term Symbol (Quantum Numbers)||7S3|
Bohr Atomic Model of Chromium - Electrons per energy level
Ground State Electronic Configuration of Chromium - neutral Chromium atom
Abbreviated electronic configuration of Chromium
The ground state abbreviated electronic configuration of Neutral Chromium atom is [Ar] 3d5 4s1. The portion of Chromium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [Ar]. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. This is important as it is the Valence electrons 3d5 4s1, electrons in the outermost shell that determine the chemical properties of the element.
Unabbreviated electronic configuration of neutral Chromium
Complete ground state electronic configuration for the Chromium atom, Unabbreviated electronic configuration
1s2 2s2 2p6 3s2 3p6 3d5 4s1
Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.
Atomic Structure of Chromium
Chromium atomic radius is 166 pm, while it's covalent radius is 127 pm.
|Atomic Radius Calculated|
166 pm (1.66 Å)
|Atomic Radius Empirical|
140 pm (1.4 Å)
|Atomic Volume||7.2824 cm3/mol|
|Covalent Radius||127 pm (1.27 Å)|
|Van der Waals Radius||-|
|Neutron Cross Section||3.1|
|Neutron Mass Absorption||0.0021|
Atomic Spectrum of Chromium
Chromium Chemical Properties: Chromium Ionization Energies and electron affinity
The electron affinity of Chromium is 64.3 kJ/mol.
Ionization Energy of Chromium
Refer to table below for Ionization energies of Chromium
|Ionization energy number||Enthalpy - kJ/mol|
Chromium Physical Properties
Refer to below table for Chromium Physical Properties
|Density||7.14 g/cm3(when liquid at m.p density is $6.3 g/cm3)|
|Molar Volume||7.2824 cm3/mol|
|Shear Modulus||115 GPa|
|Bulk Modulus||160 GPa|
Hardness of Chromium - Tests to Measure of Hardness of Element
|Mohs Hardness||8.5 MPa|
|Vickers Hardness||1060 MPa|
|Brinell Hardness||1120 MPa|
Chromium Electrical Properties
Chromium is Conductor of electricity. Refer to table below for the Electrical properties ofChromium
|Electrical Conductivity||7900000 S/m|
|Resistivity||1.3e-7 m Ω|
Chromium Heat and Conduction Properties
|Thermal Conductivity||94 W/(m K)|
|Thermal Expansion||0.0000049 /K|
Chromium Magnetic Properties
|Mass Magnetic Susceptibility||4.45e-8 m3/kg|
|Molar Magnetic Susceptibility||2.314e-9 m3/mol|
|Volume Magnetic Susceptibility||0.0003177|
Optical Properties of Chromium
Acoustic Properties of Chromium
|Speed of Sound||5940 m/s|
Chromium Thermal Properties - Enthalpies and thermodynamics
Refer to table below for Thermal properties of Chromium
|Melting Point||2180 K (1906.85°C, 3464.3299999999995 °F)|
|Boiling Point||2944 K (2670.85°C, 4839.53 °F)|
Enthalpies of Chromium
|Heat of Fusion||20.5 kJ/mol|
|Heat of Vaporization||339 kJ/mol|
|Heat of Combustion||-|
Chromium Isotopes - Nuclear Properties of Chromium
Chromium has 26 isotopes, with between 42 and 67 nucleons. Chromium has 4 stable naturally occuring isotopes.
Isotopes of Chromium - Naturally occurring stable Isotopes: 50Cr, 52Cr, 53Cr, 54Cr.
|Isotope||Z||N||Isotope Mass||% Abundance||T half||Decay Mode|