amorphous selenium from the University of Toronto

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

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba La* Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra Ac** Rf Db Sg Bh Hs Mt 110 111 112 113

Lanthanides* Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Actinides ** Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

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

Updated by clh on 2/6/98. This is not a publication of Phoenix College.

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
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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