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Cr Chromium
Element Information, Facts, Properties, Trends, Uses, Comparison with other elements

24
Cr
Chromium
Element 24 of Periodic table is Chromium with atomic number 24, atomic weight 51.9961. Chromium, symbol Cr, has a Body Centered Cubic structure and Silver color. Chromium is a Transition Metal element. It is part of group 6 (chromium family). Know everything about Chromium Facts, Physical Properties, Chemical Properties, Electronic configuration, Atomic and Crystal Structure.
24 Cr - Chromium | SchoolMyKids

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 .

Chromium Facts

Read key information and facts about element Chromium

NameChromium
Atomic Number24
Atomic SymbolCr
Atomic Weight51.9961
PhaseSolid
ColorSilver
Appearancesilvery metallic
ClassificationTransition Metal
Group in Periodic Table6
Group Namechromium family
Period in Periodic Tableperiod 4
Block in Periodic Tabled -block
Electronic Configuration[Ar] 3d5 4s1
Electronic Shell Structure (Electrons per shell)2, 8, 13, 1
Melting Point2180 K
Boiling Point2944 K
CAS NumberCAS7440-47-3
Neighborhood Elements
123456789101112131415161718
1
1
H
Hydrogen
1.008

Atomic #

Electronic Shell #

Symbol
Name
Atomic Weight
HGas
HgLiquid
CSolid
Metals
Metalloids
NonMetals
Alkali metals
Alkali earth metals
Lanthanoids
Transition metals
Post-transition metals
Other nonmetals
Halogens
Nobel gas
Actinoids
2
He
Helium
4.003
2
3
Li
Lithium
6.941
4
Be
Beryllium
9.012
5
B
Boron
10.811
6
C
Carbon
12.011
7
N
Nitrogen
14.007
8
O
Oxygen
15.999
9
F
Fluorine
18.998
10
Ne
Neon
20.180
3
11
Na
Sodium
22.990
12
Mg
Magnesium
24.305
13
Al
Aluminium
26.982
14
Si
Silicon
28.085
15
P
Phosphorus
30.974
16
S
Sulfur
32.065
17
Cl
Chlorine
35.453
18
Ar
Argon
39.948
4
19
K
Potassium
39.098
20
Ca
Calcium
40.078
21
Sc
Scandium
44.956
22
Ti
Titanium
47.867
23
V
Vanadium
50.941
24
Cr
Chromium
51.996
25
Mn
Manganese
54.938
26
Fe
Iron
55.845
27
Co
Cobalt
58.933
28
Ni
Nickel
58.693
29
Cu
Copper
63.546
30
Zn
Zinc
65.409
31
Ga
Gallium
69.723
32
Ge
Germanium
72.640
33
As
Arsenic
74.922
34
Se
Selenium
78.960
35
Br
Bromine
79.904
36
Kr
Krypton
83.798
5
37
Rb
Rubidium
85.468
38
Sr
Strontium
87.620
39
Y
Yttrium
88.906
40
Zr
Zirconium
91.224
41
Nb
Niobium
92.906
42
Mo
Molybdenum
95.940
43
Tc
Technetium
98
44
Ru
Ruthenium
101.070
45
Rh
Rhodium
102.906
46
Pd
Palladium
106.420
47
Ag
Silver
107.868
48
Cd
Cadmium
112.411
49
In
Indium
114.818
50
Sn
Tin
118.710
51
Sb
Antimony
121.760
52
Te
Tellurium
127.600
53
I
Iodine
126.904
54
Xe
Xenon
131.293
6
55
Cs
Cesium
132.905
56
Ba
Barium
137.327
57 - 71
La - Lu
Lanthanides
72
Hf
Hafnium
178.490
73
Ta
Tantalum
180.948
74
W
Tungsten
183.840
75
Re
Rhenium
186.207
76
Os
Osmium
190.230
77
Ir
Iridium
192.217
78
Pt
Platinum
195.078
79
Au
Gold
196.967
80
Hg
Mercury
200.590
81
Tl
Thallium
204.383
82
Pb
Lead
207.200
83
Bi
Bismuth
208.980
84
Po
Polonium
209
85
At
Astatine
210
86
Rn
Radon
222
7
87
Fr
Francium
223
88
Ra
Radium
226
89 - 103
Ac - Lr
Actinides
104
Rf
Rutherfordium
261
105
Db
Dubnium
262
106
Sg
Seaborgium
266
107
Bh
Bohrium
264
108
Hs
Hassium
277
109
Mt
Meitnerium
268
110
Ds
Darmstadtium
281
111
Rg
Roentgenium
272
112
Cn
Copernicium
285
113
Nh
Nihonium
284
114
Fl
Flerovium
289
115
Mc
Moscovium
288
116
Lv
Livermorium
292
117
Ts
Tennessine
294
118
Og
Oganesson
294
Lanthanides
57
La
Lanthanum
138.905
58
Ce
Cerium
140.116
59
Pr
Praseodymium
140.908
60
Nd
Neodymium
144.240
61
Pm
Promethium
145
62
Sm
Samarium
150.360
63
Eu
Europium
151.964
64
Gd
Gadolinium
157.250
65
Tb
Terbium
158.925
66
Dy
Dysprosium
162.500
67
Ho
Holmium
164.930
68
Er
Erbium
167.259
69
Tm
Thulium
168.934
70
Yb
Ytterbium
173.040
71
Lu
Lutetium
174.967
Actinides
89
Ac
Actinium
227
90
Th
Thorium
232.038
91
Pa
Protactinium
231.036
92
U
Uranium
238.029
93
Np
Neptunium
237
94
Pu
Plutonium
244
95
Am
Americium
243
96
Cm
Curium
247
97
Bk
Berkelium
247
98
Cf
Californium
251
99
Es
Einsteinium
252
100
Fm
Fermium
257
101
Md
Mendelevium
258
102
No
Nobelium
259
103
Lr
Lawrencium
262

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.

Chromium History

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 Universe15000400
Abundance in Sun20000400
Abundance in Meteorites31000001200000
Abundance in Earth's Crust14000055000
Abundance in Oceans0.60.071
Abundance in Humans304

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)

abc
291 pm291 pm291 pm

and the angles between them Lattice Angles (alpha, beta and gamma).

alphabetagamma
π/2 π/2 π/2

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 NameIm_ 3m 24 Cr Chromium - Crystal Structure | SchoolMyKids
Oxidation StatesSpace Group Number229
Crystal StructureBody 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.

Atomic Number24
Number of Electrons (with no charge)24
Number of Protons24
Mass Number52
Number of Neutrons28
Shell structure (Electrons per energy level)2, 8, 13, 1
Electron Configuration[Ar] 3d5 4s1
Valence Electrons3d5 4s1
Valence (Valency)6
Main Oxidation States2, 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

24 Cr Chromium - Electron Shell Structure | SchoolMyKids
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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.

  • As per the Aufbau principle the electrons will occupy the orbitals having lower energies before occupying higher energy orbitals. According to this principle, electrons are filled in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…
  • The Pauli exclusion principle states that a maximum of two electrons, each having opposite spins, can fit in an orbital.
  • Hund's rule states that every orbital in a given subshell is singly occupied by electrons before a second electron is filled in an orbital.
  • Electron configuration of Chromium
    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 Volume7.2824 cm3/mol
    Covalent Radius127 pm (1.27 Å)
    Van der Waals Radius-
    Neutron Cross Section3.1
    Neutron Mass Absorption 0.0021

    Atomic Spectrum of Chromium

    Atomic Spectrum of Chromium | SchoolMyKids

    Chromium Chemical Properties: Chromium Ionization Energies and electron affinity

    The electron affinity of Chromium is 64.3 kJ/mol.

    Valence6
    Electronegativity1.66
    ElectronAffinity64.3 kJ/mol

    Ionization Energy of Chromium

    Refer to table below for Ionization energies of Chromium

    Ionization energy numberEnthalpy - kJ/mol
    1st652.9
    2nd1590.6
    3rd2987
    4th4743
    5th6702
    6th8744.9
    7th15455
    8th17820
    9th20190
    10th23580
    11th26130
    12th28750
    13th34230
    14th37066
    15th97510
    16th105800
    17th114300
    18th125300
    19th134700
    20th144300
    21st157700
    22nd166090
    23rd721870
    24th761733

    Chromium Physical Properties

    Refer to below table for Chromium Physical Properties

    Density7.14 g/cm3(when liquid at m.p density is $6.3 g/cm3)
    Molar Volume7.2824 cm3/mol

    Elastic Properties

    Young Modulus279
    Shear Modulus115 GPa
    Bulk Modulus 160 GPa
    Poisson Ratio0.21

    Hardness of Chromium - Tests to Measure of Hardness of Element

    Mohs Hardness8.5 MPa
    Vickers Hardness1060 MPa
    Brinell Hardness1120 MPa

    Chromium Electrical Properties

    Chromium is Conductor of electricity. Refer to table below for the Electrical properties ofChromium

    Electrical Conductivity7900000 S/m
    Resistivity1.3e-7 m Ω
    Superconducting Point-

    Chromium Heat and Conduction Properties

    Thermal Conductivity94 W/(m K)
    Thermal Expansion0.0000049 /K

    Chromium Magnetic Properties

    Magnetic TypeAntiferromagnetic
    Curie Point-
    Mass Magnetic Susceptibility4.45e-8 m3/kg
    Molar Magnetic Susceptibility2.314e-9 m3/mol
    Volume Magnetic Susceptibility0.0003177

    Optical Properties of Chromium

    Refractive Index-

    Acoustic Properties of Chromium

    Speed of Sound5940 m/s

    Chromium Thermal Properties - Enthalpies and thermodynamics

    Refer to table below for Thermal properties of Chromium

    Melting Point2180 K (1906.85°C, 3464.3299999999995 °F)
    Boiling Point2944 K (2670.85°C, 4839.53 °F)
    Critical Temperature-
    Superconducting Point-

    Enthalpies of Chromium

    Heat of Fusion20.5 kJ/mol
    Heat of Vaporization339 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.

    IsotopeZNIsotope Mass% AbundanceT halfDecay Mode
    42Cr241842Synthetic
    43Cr241943Synthetic
    44Cr242044Synthetic
    45Cr242145Synthetic
    46Cr242246Synthetic
    47Cr242347Synthetic
    48Cr242448Synthetic
    49Cr242549Synthetic
    50Cr2426504.345%StableN/A
    51Cr242751Synthetic
    52Cr24285283.789%Stable
    53Cr2429539.501%StableN/A
    54Cr2430542.365%StableN/A
    55Cr243155Synthetic
    56Cr243256Synthetic
    57Cr243357Synthetic
    58Cr243458Synthetic
    59Cr243559Synthetic
    60Cr243660Synthetic
    61Cr243761Synthetic
    62Cr243862Synthetic
    63Cr243963Synthetic
    64Cr244064Synthetic
    65Cr244165Synthetic
    66Cr244266Synthetic
    67Cr244367Synthetic

    Regulatory and Health - Health and Safety Parameters and Guidelines

    Database Search

    List of unique identifiers to search the element in various chemical registry databases

    DatabaseIdentifier number
    CAS Number - Chemical Abstracts Service (CAS)CAS7440-47-3
    RTECS NumberRTECSGB4200000
    CID Number CID23976
    Gmelin Number-
    NSC Number-