Cs - Cesium

55
Cs
Cesium

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

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*. You can also download Printable Periodic Table of Elements Flashcards for Cesium in a PDF format.

Cesium Facts

Read key information and facts about element Cesium

NameCesium
Atomic Number55
Atomic SymbolCs
Atomic Weight132.90545
PhaseSolid
ColorSilver
Appearancesilvery gold
ClassificationAlkali Metal
Natural OccurancePrimordial
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
269
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'.

Discovered By R. Bunsen and R. Kirchhoff
Discovery Date 1860 in Germany
First Isolation 1882
Isolated by C. Setterberg

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 Uses

Caesium is used in vacuum tubes to remove trace gasses. Its major use is as a compound in drilling fluid. One of its most important uses is in the ‘caesium clock’ (atomic clock) and as a catalyst for the process of hydrogenation.

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
Space Group Number229
Crystal StructureBody Centered Cubic
Number of atoms per unit cell2
55 Cs Cesium - Crystal Structure | SchoolMyKids

The number of atoms per unit cell in a simple cubic, face-centered cubic and body-centred cubic are 1,4,2 respectively.

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 Calculated298 pm(2.98 Å)
Atomic Radius Empirical260 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

Spectral Lines of Cesium - Atomic Spectrum of Cesium

A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules.

Spectral lines are the result of interaction between a quantum system and a single photon. A spectral line may be observed either as an emission line or an absorption line.

Spectral lines are highly atom-specific, and can be used to identify the chemical composition of any medium. Several elements, including helium, thallium, and caesium, were discovered by spectroscopic means. They are widely used to determine the physical conditions of stars and other celestial bodies that cannot be analyzed by other means.

Emission spectrum of Cesium

Emission Spectrum of Cesium | SchoolMyKids

Absorption spectrum of Cesium

Absorption spectrum of Cesium is not available

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

Ionization energy is the amount of energy required to remove an electron from an atom or molecule.in chemistry, this energy is expresed in kilocalories per mole (kcal/mol) or kilojoules per mole (kJ/mol).

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

Electrical resistivity measures element's electrical resistance or how strongly it resists electric current.The SI unit of electrical resistivity is the ohm-metre (Ω⋅m). While Electrical conductivity is the reciprocal of electrical resistivity. It represents a element's ability to conduct electric current. The SI unit of electrical conductivity is siemens per metre (S/m).

Cesium is a conductor of electricity. Refer to table below for the Electrical properties of Cesium

Electrical conductors Conductor
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, 1239.530 °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

Regulatory and Health - Health and Safety Parameters and Guidelines

The United States Department of Transportation (DOT) identifies hazard class of all dangerous elements/goods/commodities either by its class (or division) number or name. The DOT has divided these materials into nine different categories, known as Hazard Classes.

Substances which in contact with water emit flammable gases

NFPA 704 is a Standard System for the Identification of the Hazards of Materials for Emergency Response. NFPA is a standard maintained by the US based National Fire Protection Association.

The health (blue), flammability (red), and reactivity (yellow) rating all use a numbering scale ranging from 0 to 4. A value of zero means that the element poses no hazard; a rating of four indicates extreme danger.

Autoignition Point-
Flashpoint-

Database Search

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

DatabaseIdentifier number
CAS Number - Chemical Abstracts Service (CAS)CAS7440-46-2
RTECS NumberRTECSFK9225000
CID Number CID5354618
Gmelin Number-
NSC Number-

Frequently Asked Questions (FAQ)

Find the answers to the most frequently asked questions about Cesium

The electronic configuration of Cesium is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s1.

The abbreviated electronic configuration of Cesium is [Xe] 6s1. To form abbreviated notation of electronic configuration, the completely filled subshells are replaced by the noble gas of the preceding period in square brackets.

Symbol of Cesium is Cs. Cesium is a chemical element with symbol Cs and atomic number 55.

Cesium is a chemical element with the symbol Cs and atomic number 55. Cesium is the 55 element on the periodic table. It is located in group 1 and period 6 in the modern periodic table.

The atomic number of Cesium is 55.

Cesium is of Silver color.

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 has 1 valence electrons. Cesium has 55 electrons out of which 1 valence electrons are present in the 6s1 outer orbitals of atom.

Melting Point of Cesium is 301.59 K.

Boiling Point of Cesium is 944 K.

Melting Point of Cesium in Kelvin is 301.59 K.

Boiling Point of Cesium in Kelvin is 944 K.

Melting Point of Cesium in Celsius is 28.44 °C.

Boiling Point of Cesium in Celsius is 670.85 °C.

Melting Point of Cesium in Fahrenheit is 83.19 °F.

Boiling Point of Cesium in Fahrenheit is 1239.53 °F.

The electronic configuration of Cesium will be 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s1.

The electronic configuration of Cesium will be 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 6s1.