Mendeleev's Periodic Table > Ir - Iridium

Ir - Iridium

This precious transition metal was discovered by Tennant in 1803 in England. The name iridium is appropriate, for its salts are highly coloured. Iridium is white, similar to platinum, but with a slight yellowish cast. It is very hard and brittle, making it very hard to machine, form, or work. It is the most corrosion resistant metal known, and was used in making the standard metre bar of Paris, which is a 90% platinum-10% iridium alloy. This metre bar has since been replaced as a fundamental unit of length (see Krypton). Iridium is not attacked by any of the acids nor by aqua regia, but is attacked by molten salts, such as NaCl and NaCN.

Ruthenium, rhodium, palladium, osmium, iridium, and platinum together make up a group of elements referred to as the platinum group metals (PGM).

Atomic number - 77 Density g/mL 22 .5
Atomic weight u 192 .22 Melting point K 2716
Bonding radius A 1 .27 Boiling point K 4701
Atomic radius A 1 .87 Heat of vaporization kJ/mol 604
Ionization Potential V 9 .1 Heat of fusion kJ/mol 26 .1
Electronegativity - 2 .2 Specific heat J/gK 0 .13
The oxide is mildly basic. Crystal are face centered cubic.
Electron config. : [Xe] 4f14 5d7 6s2

Isotopes of Ir (Iridium) :

MASS abundancy
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass		 166
5 msec
a,6.700 MeV
Re-162
165.98550 		167
5 msec
a/p,6.540 MeV
Re-163/Os-166
166.98164 		168

a,6.410 MeV
Re-164
167.97992 		169
0.4 sec
a/EC/p,6.280
Re-165/Os-169/Os-168
168.97639
MASS abundancy
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass		 170
1.05 sec
a/EC,6.170
Re-166/Os-170
169.97502 		171
1.5 sec
a/EC/p,6.159
Re-167/Os-171/Os-170
170.97180 		172
4.4 sec
a/EC,9.800
Re-168/Os-172
171.97069 		173
9.0 sec
a/EC,7.400
Re-169/Os-173
172.96770
MASS abundancy
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass		 174
9 sec
a/EC,9.000
Re-170/Os-174
173.96682 		175
9 sec
a/EC,6.600
Re-171/Os-175
174.96414 		176
8 sec
a/EC,8.000
Re-172/Os-176
175.96349 		177
30 sec
a/EC,5.700
Re-173/Os-177
176.96113
MASS abundancy
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass		 178
12 sec
EC,7.200 MeV
Os-178
177.96103 		179
79 sec
EC,4.900 MeV
Os-179
178.95909 		180
1.5 min
EC,6.400 MeV
Os-180
179.95920 		181
4.90 min
EC,4.070 MeV
Os-181
180.95757
MASS abundancy
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass		 182
15 min
EC,5.610 MeV
Os-182
181.95820 		183
57 min
EC,3.450 MeV
Os-183
182.95681 		184
3.09 hr
EC,4.600 MeV
Os-184
183.95738 		185
14.4 hr
EC,2.370 MeV
Os-185
184.95658
MASS abundancy
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass		 186
16.64 hr
EC,3.831 MeV
Os-186
185.95795 		187
10.5 hr
EC,1.502 MeV
Os-187
186.95736 		188
41.5 hr
EC,2.809 MeV
Os-188
187.95885 		189
13.2 da
EC,1.009 MeV
Os-189
188.95871
MASS abundancy
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass		 190
11.78 da
EC,2.000 MeV
Os-190
189.96059 		191 37.3%

Stable

190.96059 		192
73.830 da
B-/EC,1.460
Pt-192/Os-192
191.96260 		192a
1.45 min
B-,1.517 MeV
Pt-192
191.96266
MASS abundancy
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass		 193 62.7%

Stable

192.96292 		194
19.28 hr
B-,7.100 MeV
Pt-194
193.96507 		195
2.5 hr
B-,1.120 MeV
Pt-195
194.96597 		196
52 sec
B-,3.210 MeV
Pt-196
195.96838
MASS abundancy
Halflife
Particle, Energy
Decay Product(s)
Isotopic Mass		 196a
1.40 hr
B-,3.620 MeV
Pt-196
195.96882 		197
5.8 min
B-,2.155 MeV
Pt-197
196.96963 		198
8 sec
B-,4.100 MeV
Pt-198
197.97228