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Cs Cesium
Element Information, Facts, Properties, Trends, Uses, Comparison with other elements

55
Cs
Cesium
Element 55 of Periodic table is Cesium with atomic number 55, atomic weight 132.90545. Cesium, symbol Cs, has a Body Centered Cubic structure and Silver color. Cesium is a Alkali Metal element. It is part of group 1 (lithium family). Know everything about Cesium Facts, Physical Properties, Chemical Properties, Electronic configuration, Atomic and Crystal Structure.
55 Cs - Cesium | SchoolMyKids

Caesium or cesium is a chemical element with symbol Cs and atomic number 55. It is a soft, silvery-gold Alkali Metal with a melting point of 28 °C (82 °F), which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium is an Alkali Metal and has physical and chemical properties similar to those of rubidium and potassium.

It belongs to group 1 of the periodic table having trivial name alkali metals*. Hydrogen resides within this column, but is not considered an alkali metal.

Cesium Facts

Read key information and facts about element Cesium

NameCesium
Atomic Number55
Atomic SymbolCs
Atomic Weight132.90545
PhaseSolid
ColorSilver
Appearancesilvery gold
ClassificationAlkali Metal
Group in Periodic Table1
Group Namelithium family
Period in Periodic Tableperiod 6
Block in Periodic Tables -block
Electronic Configuration[Xe] 6s1
Electronic Shell Structure (Electrons per shell)2, 8, 18, 18, 8, 1
Melting Point301.59 K
Boiling Point944 K
CAS NumberCAS7440-46-2
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 Cesium 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 55 to find Cesium 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 Cesium on periodic table look for cross section of group 1 and period 6 in the modern periodic table.

Cesium History

The element Cesium was discovered by R. Bunsen and R. Kirchhoff in year 1860 in Germany. Cesium was first isolated by C. Setterberg in 1882. Cesium derived its name from the Latin caesius, meaning 'sky blue'.

Bunsen and Kirchhoff were the first to suggest finding new elements byspectrum analysis. They discovered caesium by its two blueemission linesin a sample ofDürkheimmineral water. The pure metal was eventually isolated in 1882 by Setterberg.

Cesium Presence: Abundance in Nature and Around Us

The table below shows the abundance of Cesium 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 Universe0.80.01
Abundance in Sun80.07
Abundance in Meteorites14020
Abundance in Earth's Crust1900290
Abundance in Oceans0.50.023
Abundance in Humans201

Crystal Structure of Cesium

The solid state structure of Cesium 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
614.1 pm614.1 pm614.1 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 55 Cs Cesium - Crystal Structure | SchoolMyKids
Oxidation StatesSpace Group Number229
Crystal StructureBody Centered Cubic

Cesium Atomic and Orbital Properties

Cesium atoms have 55 electrons and the electronic shell structure is [2, 8, 18, 18, 8, 1] with Atomic Term Symbol (Quantum Numbers) 2S1/2.

Atomic Number55
Number of Electrons (with no charge)55
Number of Protons55
Mass Number133
Number of Neutrons78
Shell structure (Electrons per energy level)2, 8, 18, 18, 8, 1
Electron Configuration[Xe] 6s1
Valence Electrons6s1
Valence (Valency)1
Main Oxidation States1
Oxidation States-1, 1
Atomic Term Symbol (Quantum Numbers)2S1/2

Bohr Atomic Model of Cesium - Electrons per energy level

55 Cs Cesium - Electron Shell Structure | SchoolMyKids
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Ground State Electronic Configuration of Cesium - neutral Cesium atom

Abbreviated electronic configuration of Cesium

The ground state abbreviated electronic configuration of Neutral Cesium atom is [Xe] 6s1. The portion of Cesium configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [Xe]. 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 6s1, electrons in the outermost shell that determine the chemical properties of the element.

Unabbreviated electronic configuration of neutral Cesium

Complete ground state electronic configuration for the Cesium atom, Unabbreviated electronic configuration

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s1

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 Cesium
    Atomic Structure of Cesium

    Cesium atomic radius is 298 pm, while it's covalent radius is 225 pm.

    Atomic Radius Calculated

    298 pm (2.98 Å)

    Atomic Radius Empirical

    260 pm (2.6 Å)

    Atomic Volume70.732 cm3/mol
    Covalent Radius225 pm (2.25 Å)
    Van der Waals Radius343 pm
    Neutron Cross Section29
    Neutron Mass Absorption 0.0077

    Atomic Spectrum of Cesium

    Atomic Spectrum of Cesium | SchoolMyKids

    Cesium Chemical Properties: Cesium Ionization Energies and electron affinity

    The electron affinity of Cesium is 45.5 kJ/mol.

    Valence1
    Electronegativity0.79
    ElectronAffinity45.5 kJ/mol

    Ionization Energy of Cesium

    Refer to table below for Ionization energies of Cesium

    Ionization energy numberEnthalpy - kJ/mol
    1st375.7
    2nd2234.3
    3rd3400

    Cesium Physical Properties

    Refer to below table for Cesium Physical Properties

    Density1.879 g/cm3(when liquid at m.p density is $1.843 g/cm3)
    Molar Volume70.732 cm3/mol

    Elastic Properties

    Young Modulus1.7
    Shear Modulus-
    Bulk Modulus 1.6 GPa
    Poisson Ratio-

    Hardness of Cesium - Tests to Measure of Hardness of Element

    Mohs Hardness0.2 MPa
    Vickers Hardness-
    Brinell Hardness0.14 MPa

    Cesium Electrical Properties

    Cesium is Conductor of electricity. Refer to table below for the Electrical properties ofCesium

    Electrical Conductivity5000000 S/m
    Resistivity2e-7 m Ω
    Superconducting Point-

    Cesium Heat and Conduction Properties

    Thermal Conductivity36 W/(m K)
    Thermal Expansion-

    Cesium Magnetic Properties

    Magnetic TypeParamagnetic
    Curie Point-
    Mass Magnetic Susceptibility2.8e-9 m3/kg
    Molar Magnetic Susceptibility3.72e-10 m3/mol
    Volume Magnetic Susceptibility0.00000526

    Optical Properties of Cesium

    Refractive Index-

    Acoustic Properties of Cesium

    Speed of Sound-

    Cesium Thermal Properties - Enthalpies and thermodynamics

    Refer to table below for Thermal properties of Cesium

    Melting Point301.59 K (28.44°C, 83.192 °F)
    Boiling Point944 K (670.85°C, 1239.5300000000002 °F)
    Critical Temperature1938 K
    Superconducting Point-

    Enthalpies of Cesium

    Heat of Fusion2.09 kJ/mol
    Heat of Vaporization65 kJ/mol
    Heat of Combustion-

    Cesium Isotopes - Nuclear Properties of Cesium

    Cesium has 40 isotopes, with between 112 and 151 nucleons. Cesium has 1 stable naturally occuring isotopes.

    Isotopes of Cesium - Naturally occurring stable Isotopes: 133Cs.

    IsotopeZNIsotope Mass% AbundanceT halfDecay Mode
    112Cs5557112Synthetic
    113Cs5558113Synthetic
    114Cs5559114Synthetic
    115Cs5560115Synthetic
    116Cs5561116Synthetic
    117Cs5562117Synthetic
    118Cs5563118Synthetic
    119Cs5564119Synthetic
    120Cs5565120Synthetic
    121Cs5566121Synthetic
    122Cs5567122Synthetic
    123Cs5568123Synthetic
    124Cs5569124Synthetic
    125Cs5570125Synthetic
    126Cs5571126Synthetic
    127Cs5572127Synthetic
    128Cs5573128Synthetic
    129Cs5574129Synthetic
    130Cs5575130Synthetic
    131Cs5576131Synthetic
    132Cs5577132Synthetic
    133Cs5578133100%Stable
    134Cs5579134Synthetic
    135Cs5580135Synthetic
    136Cs5581136Synthetic
    137Cs5582137Synthetic
    138Cs5583138Synthetic
    139Cs5584139Synthetic
    140Cs5585140Synthetic
    141Cs5586141Synthetic
    142Cs5587142Synthetic
    143Cs5588143Synthetic
    144Cs5589144Synthetic
    145Cs5590145Synthetic
    146Cs5591146Synthetic
    147Cs5592147Synthetic
    148Cs5593148Synthetic
    149Cs5594149Synthetic
    150Cs5595150Synthetic
    151Cs5596151Synthetic