Se - Selenium

Selenium was discovered by J. J. Berzelius in 1817 in Sweden.

Atomic number - 34 Density g/mL 4 .8
Atomic weight u 78 .96 Melting point K 494
Bonding radius A 1 .16 Boiling point K 958
Atomic radius A 1 .22 Heat of vaporization kJ/mol 37 .7
Ionization Potential V 9 .752 Heat of fusion kJ/mol 6 .694
Electronegativity - 2 .55 Specific heat J/gK 0 .32
The oxide is a strong acid.
Crystal are hexagonal.

Electron config. : [Ar] 3d10 4s2 4p4


Isotopes of Se: Click mass number for decay process, product for element page.


065
50 msec
EC,14.100 MeV
As-65
64.964680
067
107 msec
EC/ECp,10.150
As-67/Ge-66
66.950090
068
35.5 sec
EC,4.700 MeV
As-68
67.941921
069
27.4 sec
EC/ECp,6.780
As-69/Ge-68
68.939559
070
41.1 min
EC,2.400 MeV
As-70
69.933504
071
4.74 min
EC,4.800 MeV
As-71
70.932270
072
8.40 da
EC,4.356 MeV
As-72
71.927112
073
7.15 hr
EC,2.740 MeV
As-73
72.926767
074 0.89%

Stable

73.922476
075
119.79 da
EC,1.316 MeV
As-75
74.922523
076 9.36%

Stable

75.919214
077 7.63%

Stable

76.919914
078 23.78%

Stable

77.917309
079
6.5E+5 yr
B-,2.281 MeV
Br-79
78.918499
080 49.61%

Stable

79.916522
081
18.45 min
B-,1.585 MeV
Br-81
80.917992
082 8.73%
1.08E+20 yr
B-B-,2.995
Kr-82
81.916700
083
22.3 min
B-,3.668 MeV
Br-83
82.919119
084
3.1 min
B-,1.830 MeV
Br-84
83.918464
085
31.7 sec
B-,6.182 MeV
Br-85
84.922243
086
15.3 sec
B-,5.099 MeV
Br-86
85.924276
087
5.29 sec
B-/B-n,7.280
Br-87/Br-86
86.928523
088
1.53 sec
B-/B-n,6.850
Br-88/Br-87
87.931432
089
0.41 sec
B-/B-n,9.000
Br-89/Br-88
88.936016
091
0.27 sec
B-/B-n,10.700
Br-91/Br-90
90.945356
MASS abund.
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass