Thorium Element (Periodic Table)

Thorium

Thorium (Th) is a chemical element of the periodic table, located in the period 7, and has the atomic number 90. It is the second element in the actinide series. It is a silvery metal that turns gray or black, when it is exposed to air. It is named after Thor, the Norse god of thunder. It is counted as one of the radioactive elements.

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
– f block

FAQs on Thorium Element

Thorium
‣ What does thorium look like?

Appearance: silvery, often with black tarnish
‣ Who discovered thorium? When was thorium discovered?

Discovery: Jons Jacob Berzelius (1829)
‣ Where is thorium on the periodic table?

Thorium Periodic Table

Location: Thorium is found in the seventh row of the periodic table, next to the actinium element.
‣ What’s the atomic number of thorium?

Atomic number (Z): 90
‣ What’s the symbol for thorium?

Symbol: Th
Thorium atomic weight: 232.0377
‣ Which block does thorium belong to?

Block: f-block
‣ What period is thorium in on the periodic table?

Period: 7
Atomic radius of thorium: empirical: 179.8 pm
Thorium covalent radius: 206±6 pm
‣ What is the melting point of thorium?

Melting point: 2023 K (1750 °C, 3182 °F)
‣ What is the boiling point of thorium?

Boiling point: 5061 K (4788 °C, 8650 °F)
‣ How many electron shells does thorium have?

Electrons per shell: 2, 8, 18, 32, 18, 10, 2
‣ What is the electron configuration of thorium?

Electron configuration: [Rn] 6d2 7s2
Thorium ionization energies:
1st: 587 kJ/mol
2nd: 1110 kJ/mol
3rd: 1930 kJ/mol
‣ What is the phase of thorium?

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

Density (near r.t): 11.7 g/cm3
Thorium magnetic ordering: paramagnetic
Thorium natural occurrence: primordial
‣ What is the most common oxidation state of thorium?

Oxidation state: +4
‣ What’s the electronegativity of thorium?

Electronegativity: Pauling scale: 1.3
Thorium poisson’s ratio: 0.27
Thorium heat of fusion: 13.81 kJ/mol
Thorium heat of vaporization: 514 kJ/mol
Thorium molar heat capacity: 26.230 J/(mol K)
Thorium molar magnetic susceptibility: +132.0 × 10-6 cm3/mol (293 K)
Speed of sound in thorium: 2490 m/s (at 20 °C)
‣ What is the crystal structure of thorium?

Crystal structure: face-centered cubic (fcc) 
Thermal expansion of thorium: 11.0 µm/(m.K) (at 25 °C)
Thermal conductivity of thorium: 54.0 W/(m.K)
Thorium electrical resistivity: 157 nΩ.m (at 0 °C)
‣ Thorium hardness

Mohs hardness: 3.0
Vickers hardness: 295-685 MPa
Brinell hardness: 390-1500 MPa
Young’s modulus of thorium: 79 GPa
Shear modulus of thorium: 31 GPa
Bulk modulus of thorium: 54 GPa
Thorium CAS number: 7440-29-1

‣ Thorium vapor pressure

Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)263329073248368342595055

‣ How many isotopes does thorium have?

Main isotopes of thorium
IsotopeAbundanceHalf-life (t1/2)Decay modeProduct
227Thtrace18.68 dα223Ra
228Thtrace1.9116 yα224Ra
229Thtrace7917 yα225Ra
230Th0.02 %75400 yα226Ra
231Thtrace25.5 hβ231Pa
232Th99.98 %1.405 × 1010 yα228Ra
234Thtrace24.1 dβ234Pa

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