Selenium Element (Periodic Table)

Selenium

Selenium (Se) is a chemical element of the periodic table, located in the group 16 and the period 4, and has the atomic number 34. It is a red powder or black reactive nonmetal, whose name comes from the Greek word “selene”, which means Moon. It is a member of the chalcogen group.

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
– p block

FAQs on Selenium Element

Selenium
‣ What does selenium look like?

Appearance: grey metallic-looking, red, and vitreous black (not pictured) allotropes
‣ Who discovered selenium? When was selenium discovered?

Discovery and first isolation: Jons Jakob Berzelius and Johann Gottlieb Gahn (1817)
‣ Where is selenium located on the periodic table?

Selenium Periodic Table

Location: Selenium is found in the fourth row of the periodic table below the sulfur element.
‣ What is selenium’s atomic number?

Atomic number (Z): 34
‣ What is the symbol for selenium?

Symbol: Se
‣ What is the atomic weight of selenium?

Standard atomic weight: 78.971
‣ What is the block of selenium?

Block: p-block
‣ What group is selenium in on the periodic table?

Group: 16 (chalcogens)
‣ Which period is selenium on the periodic table?

Period: 4
‣ What is the atomic radius of selenium (atomic number 34)?

Atomic radius: empirical: 120 pm
Selenium covalent radius: 120±4 pm
Selenium Van der Waals radius: 190 pm
‣ What is the melting point of selenium?

Melting point: 494 K (221 °C, 430 °F)
‣ What is the boiling point of selenium?

Boiling point: 958 K (685 °C, 1265 °F)
Selenium critical point: 1766 K, 27.2 MPa
‣ How many electron shells does selenium have?

Electrons per shell: 2, 8, 18, 6
‣ What is the ground state electron configuration of selenium?

Electron configuration: [Ar] 3d10 4s2 4p4
‣ What is the ionization energy of selenium?

Ionization energies:
1st: 941.0 kJ/mol
2nd: 2045 kJ/mol
3rd: 2973.7 kJ/mol
‣ What is the phase of selenium at room temperature?

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

Density (near r.t): gray: 4.81 g/cm3
alpha: 4.39 g/cm3
vitreous: 4.28 g/cm3

when liquid (at m.p): 3.99 g/cm3
Selenium magnetic ordering: diamagnetic
Selenium natural occurrence: primordial
‣ What is the oxidation state of selenium?

Oxidation state: 0, -2, +4, +6
‣ What’s the electronegativity of selenium?

Electronegativity: Pauling scale: 2.55
Selenium poisson’s ratio: 0.33
Selenium heat of fusion: gray: 6.69 kJ/mol
Selenium heat of vaporization: 95.48 kJ/mol
Selenium molar heat capacity: 25.363 J/(mol K)
Selenium molar magnetic susceptibility: -25.0 × 10-6 cm3/mol (298 K)
Speed of sound in selenium: 3350 m/s (at 20 °C)
Selenium crystal structure: hexagonal
Thermal expansion of selenium: amorphous: 37 µm/(m.K) (at 25 °C)
Thermal conductivity of selenium: amorphous: 0.519 W/(m.K)
‣ What is the hardness of selenium?

Mohs hardness: 2.0
Brinell hardness: 736 MPa
Young’s modulus of selenium: 10 GPa
Shear modulus of selenium: 3.7 GPa
Bulk modulus of selenium: 8.3 GPa
Selenium CAS number: 7782-49-2

‣ Selenium vapor pressure

Vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)500552617704813958

‣ How many isotopes does selenium have?

Main isotopes of selenium
IsotopeAbundanceHalf-life (t1/2)Decay modeProduct
72Sesyn8.4 dε
γ
72As
74Se0.86 %stable
75Sesyn119.8 dε
γ
75As
76Se9.23 %stable
77Se7.60 %stable
78Se23.69 %stable
79Setrace3.27 × 105 yβ79Br
80Se49.80 %stable
82Se8.82 %1.08 × 1020 yββ82Kr

.
.
.

Related:

Also Read:

Leave a Comment