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

24
Cr
Chromium

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. 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.

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.

Table of Contents

Chromium History

The element Chromium was discovered by Louis Nicolas Vauquelin in year 1797 in France . Chromium derived its name from the Greek word chroma, meaning 'color'

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 %)
Abundance in Universe 1.5e-05
Abundance in Sun 2e-05
Abundance in Meteorites 0.003
Abundance in Earth's Crust 0.00014
Abundance in Oceans 6×10-8%
Abundance in Humans 3×10-6%

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)

a b c
291 291 291 pm

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

alpha beta gamma
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 Name Im_ 3m 24 Cr Chromium - Crystal Structure | SchoolMyKids
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.

Atomic Number 24
Number of Electrons (with no charge) 24
Number of Protons 24
Mass Number 52
Number of Neutrons 28
Shell structure (Electrons per energy level) [2, 8, 13, 1]
Electron Configuration [Ar] 3d5 4s1
Valence Electrons 3d5 4s1
Oxidation State -4;-2;-1
1;2;3;4;5;6
Atomic Term Symbol (Quantum Numbers) 7S3

Shell Structure of Chromium - Electrons per energy level

24 Cr Chromium - Electron Shell Structure | SchoolMyKids
n s p d f
1 K 2
2 L 2 6
3 M 2 6 5
4 N 1

Ground State Electronic Configuration of Chromium - neutral Chromium atom

The ground state 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

Atomic Structure of Chromium

Chromium atomic radius is 166 pm, while it's covalent radius is 127 pm.

Atomic Radius

166 pm (1.66 Å)

Atomic Volume 7.28236694678 cm3
Covalent Radius 127 pm (1.27 Å)
Van der Waals Radius N/A
Neutron Cross Section 3.1 σa/barns

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

Valence 6
Electronegativity 1.66
ElectronAffinity 64.3 kJ/mol

Ionization Energy of Chromium

Refer to table below for Ionization energies of Chromium

Ionization energy number Enthalpy - kJ/mol
1 652.9
2 1590.6
3 2987
4 4743
5 6702
6 8744.9
7 15455
8 17820
9 20190
10 23580
11 26130
12 28750
13 34230
14 37066
15 97510
16 1.058×105
17 1.143×105
18 1.253×105
19 1.347×105
20 1.443×105
21 1.577×105

Chromium Physical Properties

Refer to below table for Chromium Physical Properties

Density 7.14 g/cm3
Molar Volume 7.28236694678 cm3

Elastic Properties

Young Modulus 279 GPa
Shear Modulus 115 GPa
Bulk Modulus 160 GPa
Poisson Ratio 0.21

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 of Chromium

Electrical Conductivity 7.9×106 S/m
Resistivity 1.3×10-7 m Ω
Superconducting Point N/A

Chromium Heat and Conduction Properties

Thermal Conductivity 94 W/(m K)
Thermal Expansion 4.9×10-6 K-1

Chromium Magnetic Properties

Magnetic Type Antiferromagnetic
Curie Point N/A
Mass Magnetic Susceptibility 4.45×10-8
Molar Magnetic Susceptibility 2.314×10-9
Volume Magnetic Susceptibility 0.0003177

Optical Properties of Chromium

Refractive Index N/A

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 (1907 °C)
Boiling Point 2944 K (2671 °C)
Critical Temperature N/A
Superconducting Point N/A

Enthalpies of Chromium

Heat of Fusion 20.5 kJ/mol
Heat of Vaporization 339 kJ/mol
Heat of Combustion N/A

Chromium Isotopes - Nuclear Properties of Chromium

Isotopes of rhodium. Naturally occurring Chromium has 4 stable isotope - 50Cr, 52Cr, 53Cr, 54Cr.

Isotope Isotope Mass % Abundance T half Decay Mode
42Cr  
43Cr  
44Cr  
45Cr  
46Cr  
47Cr  
48Cr  
49Cr  
50Cr   4.345% Stable N/A
51Cr  
52Cr   83.789% Stable N/A
53Cr   9.501% Stable N/A
54Cr   2.365% Stable N/A
55Cr  
56Cr  
57Cr  
58Cr  
59Cr  
60Cr  
61Cr  
62Cr  
63Cr  
64Cr  
65Cr  
66Cr  
67Cr  

Regulatory and Health - Health and Safety Parameters and Guidelines

CAS Number CAS7440-47-3
RTECS Number RTECSGB4200000
DOT Hazard Class 4.1
DOT Numbers 3089
EU Number N/A
NFPA Fire Rating 1
NFPA Hazards N/A
NFPA Health Rating 2
NFPA Reactivity Rating 1
Autoignition Point 400 °C
Flashpoint N/A

Database Search

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

Database Identifier number
CAS Number - Chemical Abstracts Service (CAS) CAS7440-47-3
CID Number CID23976
Gmelin Number N/A
NSC Number N/A
RTECS Number RTECSGB4200000

List of Elements
1 H - Hydrogen
2 He - Helium
3 Li - Lithium
4 Be - Beryllium
5 B - Boron
6 C - Carbon
7 N - Nitrogen
8 O - Oxygen
9 F - Fluorine
10 Ne - Neon
11 Na - Sodium
12 Mg - Magnesium
13 Al - Aluminium
14 Si - Silicon
15 P - Phosphorus
16 S - Sulfur
17 Cl - Chlorine
18 Ar - Argon
19 K - Potassium
20 Ca - Calcium
21 Sc - Scandium
22 Ti - Titanium
23 V - Vanadium
24 Cr - Chromium
25 Mn - Manganese
26 Fe - Iron
27 Co - Cobalt
28 Ni - Nickel
29 Cu - Copper
30 Zn - Zinc
31 Ga - Gallium
32 Ge - Germanium
33 As - Arsenic
34 Se - Selenium
35 Br - Bromine
36 Kr - Krypton
37 Rb - Rubidium
38 Sr - Strontium
39 Y - Yttrium
40 Zr - Zirconium
41 Nb - Niobium
42 Mo - Molybdenum
43 Tc - Technetium
44 Ru - Ruthenium
45 Rh - Rhodium
46 Pd - Palladium
47 Ag - Silver
48 Cd - Cadmium
49 In - Indium
50 Sn - Tin
51 Sb - Antimony
52 Te - Tellurium
53 I - Iodine
54 Xe - Xenon
55 Cs - Cesium
56 Ba - Barium
57 La - Lanthanum
58 Ce - Cerium
59 Pr - Praseodymium
60 Nd - Neodymium
61 Pm - Promethium
62 Sm - Samarium
63 Eu - Europium
64 Gd - Gadolinium
65 Tb - Terbium
66 Dy - Dysprosium
67 Ho - Holmium
68 Er - Erbium
69 Tm - Thulium
70 Yb - Ytterbium
71 Lu - Lutetium
72 Hf - Hafnium
73 Ta - Tantalum
74 W - Tungsten
75 Re - Rhenium
76 Os - Osmium
77 Ir - Iridium
78 Pt - Platinum
79 Au - Gold
80 Hg - Mercury
81 Tl - Thallium
82 Pb - Lead
83 Bi - Bismuth
84 Po - Polonium
85 At - Astatine
86 Rn - Radon
87 Fr - Francium
88 Ra - Radium
89 Ac - Actinium
90 Th - Thorium
91 Pa - Protactinium
92 U - Uranium
93 Np - Neptunium
94 Pu - Plutonium
95 Am - Americium
96 Cm - Curium
97 Bk - Berkelium
98 Cf - Californium
99 Es - Einsteinium
100 Fm - Fermium
101 Md - Mendelevium
102 No - Nobelium
103 Lr - Lawrencium
104 Rf - Rutherfordium
105 Db - Dubnium
106 Sg - Seaborgium
107 Bh - Bohrium
108 Hs - Hassium
109 Mt - Meitnerium
110 Ds - Darmstadtium
111 Rg - Roentgenium
112 Cn - Copernicium
113 Nh - Nihonium
114 Fl - Flerovium
115 Mc - Moscovium
116 Lv - Livermorium
117 Ts - Tennessine
118 Og - Oganesson
Metalloid
Nonmetals
Other Nonmetals
Halogens Noble Gas
Metals
Alkali Metals Alkaline Earth Metals
Transition Metals Post-Transition Metals
Lanthanide Actinide