Os - Osmium

A precious metal. Osmium is used in ball pens, as a forensic stain, and in electronic applications. Discovered in 1804 by Englishman Smithson Tennent in the residue left by dissolving platinum in aqua regia. A comprehensive guide to the simple chemistry of the metal can be found in The Chemistry of the Rarer Platinum Metals (John Wiley, New York, 1967).

Powdered osmium is oxidized in air at room temperature to form highly toxic osmium tetroxide. Found naturally with iridium, paladium, rhodium and platinum. Due to the high cost of osmium, there is none in our lab.

Atomic number - 76 Density g/mL 22 .4
Atomic weight u 190 .2 Melting point K 3300
Bonding radius A 1 .26 Boiling point K 5285
Atomic radius A 1 .92 Heat of vaporization kJ/mol 746
Ionization Potential V 8 .7 Heat of fusion kJ/mol 31 .8
Electronegativity - 2 .2 Specific heat J/gK 0 .13
The oxide is mildly acidic.
Crystal are hexagonal.

Electron config. : [Xe] 4f14 5d6 6s2

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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 Os: Click mass number for decay process, product for element page.
162
1.9 msec
a,6.780 MeV
W-158
161.98378 		163

a/EC,9.400
W-159/Re-163
162.98207 		164
41 msec
a/EC,6.478
W-160/Re-164
163.97788 		165
73 msec
a/EC,6.320
W-161/Re-165
164.97648 		166
194 msec
a/EC,6.131
W-162/Re-166
165.97252 		167
0.83 sec
a/EC,5.980
W-163/Re-167
166.97133 		168
2.2 sec
a/EC,5.700
W-164/Re-168
167.96775
169
3.4 sec
a/EC,7.680
W-165/Re-169
168.96707 		170
7.3 sec
a/EC,5.000
W-166/Re-170
169.96356 		171
8.0 sec
a/EC,7.100
W-167/Re-171
170.96307 		172
19.2 sec
a/EC,4.500
W-168/Re-172
171.96007 		173
16 sec
a/EC,6.300
W-169/Re-173
172.95974 		174
44 sec
a/EC,3.700
W-170/Re-174
173.95716 		175
1.4 min
EC,5.300 MeV
Re-175
174.95705
176
3.6 min
EC,3.200 MeV
Re-176
175.95496 		177
2.8 min
EC,4.500 MeV
Re-177
176.95512 		178
5.0 min
EC,2.300 MeV
Re-178
177.95335 		179
6.5 min
EC,3.680 MeV
Re-179
178.95393 		180
21.5 min
EC,1.470 MeV
Re-180
179.95235 		181
105 min
EC,2.930 MeV
Re-181
180.95321 		182
22.10 hr
EC,2.800 MeV
Re-182
181.95218
183
13.0 hr
EC,2.130 MeV
Re-183
182.95310 		184 0.020%
5.6E13 yr
,1.671 MeV

183.95249 		185
93.6 da
EC,1.013 MeV
Re-185
184.95404 		186 1.58%
2.0E+15 yr
a,2.822 MeV
W-182
185.95383 		187 1.6%

Stable

186.95574 		188 13.3%

Stable

187.95583 		189 16.1%

Stable

188.95814
190 26.4%

Stable

189.95844 		191
15.4 da
B-,2.045 MeV
Ir-191
190.96092 		192 41.0%

B-Stable
Ir-192
191.96147 		193
30.5 hr
B-,1.140 MeV
Ir-193
192.96414 		194
6.0 yr
B-,7.100 MeV
Ir-194
193.96517 		195
6.5 min
B-,2.000 MeV
Ir-195
194.96811 		196
34.9 min
B-,1.160 MeV
Ir-196
195.96961
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.