Caesium Element (Periodic Table)

Caesium

Caesium (Cs), also spelled as cesium in American English, is a chemical element of the periodic table, located in group 1 and period 6, and has the atomic number 55. It is a soft, silvery-gold alkali metal whose name comes from the Latin word “caesius” (which means sky blue). It is a highly reactive metal.

group
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
period
1
1
H
2
He
2
3
Li
4
Be
5
B
6
C
7
N
8
O
9
F
10
Ne
3
11
Na
12
Mg
13
Al
14
Si
15
P
16
S
17
Cl
18
Ar
4
19
K
20
Ca
21
Sc
22
Ti
23
V
24
Cr
25
Mn
26
Fe
27
Co
28
Ni
29
Cu
30
Zn
31
Ga
32
Ge
33
As
34
Se
35
Br
36
Kr
5
37
Rb
38
Sr
39
Y
40
Zr
41
Nb
42
Mo
43
Tc
44
Ru
45
Rh
46
Pd
47
Ag
48
Cd
49
In
50
Sn
51
Sb
52
Te
53
I
54
Xe
6
55
Cs
56
Ba
72
Hf
73
Ta
74
W
75
Re
76
Os
77
Ir
78
Pt
79
Au
80
Hg
81
Tl
82
Pb
83
Bi
84
Po
85
At
86
Rn
7
87
Fr
88
Ra
104
Rf
105
Db
106
Sg
107
Bh
108
Hs
109
Mt
110
Ds
111
Rg
112
Cn
113
Nh
114
Fl
115
Mc
116
Lv
117
Ts
118
Og
57
La
58
Ce
59
Pr
60
Nd
61
Pm
62
Sm
63
Eu
64
Gd
65
Tb
66
Dy
67
Ho
68
Er
69
Tm
70
Yb
71
Lu
89
Ac
90
Th
91
Pa
92
U
93
Np
94
Pu
95
Am
96
Cm
97
Bk
98
Cf
99
Es
100
Fm
101
Md
102
No
103
Lr
– s block

Caesium Applications (or Uses)

Here are the applications (or uses) of caesium:

  • Caesium is used in the petroleum industry as a drilling fluid to lubricate drill bits
  • Caesium is used in photoelectric cells to convert sunlight into electricity
  • Caesium is used in an atomic clock
  • Caesium is used as a getter in vacuum tubes
  • Caesium is used in cancer treatment
  • Caesium is used in lasers and fluorescent lamps
  • Caesium and its compounds are used as an oxidizer in infrared flares
  • Caesium is used to sterilize food and medical products
  • Caesium is added as a carbonate in optical glass to improve stability and durability
  • Caesium is used as a propellant in ion engines used by space vehicles

Caesium Facts

Here are the facts about caesium:

  • Caesium was discovered using a flame emission spectroscopy method
  • Caesium has a very low melting point that if you place it on your hand, it will melt
  • Caesium reacts explosively with oxygen and water, so it is stored in mineral oil or kerosene
  • Caesium is also the most reactive metal, along with francium
  • Caesium has only one stable isotope: 133Cs
  • Caesium is the 47th most abundant element on earth
  • Caesium is the most electropositive chemical element

FAQs on Caesium Element

Caesium
‣ What does caesium look like?

Appearance: pale gold
‣ When was caesium discovered and by whom?

Discovery: Robert Bunsen and Gustav Kirchhoff (1860)
First isolation: Carl Setterberg (1882)
‣ What column is caesium in on the periodic table?

Caesium Periodic Table

Location: Caesium is found in the first column of the periodic table below the rubidium element.
‣ What is caesium’s atomic number?

Atomic number (Z): 55
‣ What’s the symbol for caesium?

Symbol: Cs
Atomic weight of caesium: 132.90545196
‣ What block is caesium in the periodic table?

Block: s-block
‣ Which group is caesium in the periodic table?

Group: 1 (hydrogen and alkali metals)
‣ What period is caesium located in?

Period: 6
‣ What is the atomic radius of caesium?

Atomic radius: empirical: 265 pm
Caesium covalent radius: 244±11 pm
Caesium Van der Waals radius: 343 pm
‣ What is caesium’s melting point?

Melting point: 301.7 K (28.5 °C, 83.3 °F)
‣ What is caesium’s boiling point?

Boiling point: 944 K (671 °C, 1240 °F)
Caesium critical point: 1938 K, 9.4 MPa
‣ How many electron shells does caesium have?

Electrons per shell: 2, 8, 18, 18, 8, 1
‣ What is the electron configuration of caesium?

Electron configuration: [Xe] 6s1
‣ What is the ionization energy of caesium?

Ionization energies:
1st: 375.7 kJ/mol
2nd: 2234.3 kJ/mol
3rd: 3400 kJ/mol
‣ What phase is caesium at room temperature?

Phase (at r.t): solid
‣ What is the density of caesium?

Density (near r.t): 1.93 g/cm3
when liquid (at m.p): 1.843 g/cm3
Caesium magnetic ordering: paramagnetic
Caesium natural occurrence: primordial
‣ What is the oxidation state of caesium?

Oxidation state: +1
‣ What’s the electronegativity of caesium?

Electronegativity: Pauling scale: 0.79
Caesium heat of fusion: 2.09 kJ/mol
Caesium heat of vaporization: 63.9 kJ/mol
Caesium molar heat capacity: 32.210 J/(mol K)
‣ What is the crystal structure of caesium?

Crystal structure: body-centered cubic (bcc)
Caesium thermal expansion: 97 µm/(m.K) (at 25 °C)
Thermal conductivity of caesium: 35.9 W/(m.K)
Caesium electrical resistivity: 205 nΩ.m (at 20 °C)
‣ What is the hardness of caesium?

Mohs hardness: 0.2
Brinell hardness: 0.14 MPa
Young’s modulus of caesium: 1.7 GPa
Bulk modulus of caesium: 1.6 GPa
Caesium CAS number: 7440-46-2

‣ Caesium vapor pressure

Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)418469534623750940

‣ How many isotopes does caesium have?

Main isotopes of caesium
IsotopeAbundanceHalf-life (t1/2)Decay modeProduct
133Cs100 %stable
134Cssyn2.0648 yε
β
134Xe
134Ba
135Cstrace2.3 × 106 yβ135Ba
137Cssyn30.17 yβ137Ba

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