Naturally occurring platinum (78Pt) consists of five stable isotopes (192Pt, 194Pt, 195Pt, 196Pt, 198Pt) and one long-lived (half-life 4.83×1011 years) radioisotope (190Pt). There are also 34 known synthetic radioisotopes ranging from 165Pt to 204Pt, and longest-lived of those is 193Pt with a half-life of 50 years. All the others have half-lives under two weeks, most under a day. There are numerous metastable states, of which the most stable are 193mPt and 195mPt with half-lives 4.33 and 4.010 days, decaying to their ground states.
Despite the obstacles to measurement with rare isotopes of rare elements, with a very slow decay, the 190Pt/186Os system has been used in isotope geology, though not directly for dating.
All isotopes of platinum are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed. Platinum-195 is the most abundant isotope, making platinum one of the only three elements to have its most abundant isotope with an odd neutron number (the other two being beryllium and nitrogen); however, it is so only by a small margin, unlike the other two, and is more in the nature of a coincidence.
List of isotopes
|-id=Platinum-165 | 165Pt | style="text-align:right" | 78 | style="text-align:right" | 87 | 164.99966(43)# | style="text-align:center" | 2019 | 370(180) μs | α | 161Os | 7/2−#
|-id=Platinum-166 | 166Pt | style="text-align:right" | 78 | style="text-align:right" | 88 | 165.99487(32)# | style="text-align:center" | 1996 | 294(62) μs | α | 162Os | 0+
|-id=Platinum-167 | 167Pt | style="text-align:right" | 78 | style="text-align:right" | 89 | 166.99275(33)# | style="text-align:center" | 1996 | 920(120) μs | α | 163Os | 7/2−#
|-id=Platinum-168 | rowspan=2|168Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 90 | rowspan=2|167.98818(16) | rowspan=2 style="text-align:center" | 1981 | rowspan=2|2.02(10) ms | α | 164Os | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β+ ? | 168Ir |-id=Platinum-169 | rowspan=2|169Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 91 | rowspan=2|168.98662(22)# | rowspan=2 style="text-align:center" | 1981 | rowspan=2|6.99(9) ms | α | 165Os | rowspan=2|(7/2−) | rowspan=2| | rowspan=2| |- | β+ ? | 169Ir |-id=Platinum-170 | rowspan=2|170Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 92 | rowspan=2|169.982502(20) | rowspan=2 style="text-align:center" | 1981 | rowspan=2|13.93(16) ms | α | 166Os | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β+ ? | 170Ir |-id=Platinum-171 | rowspan=2|171Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 93 | rowspan=2|170.981249(87) | rowspan=2 style="text-align:center" | 1981 | rowspan=2|45.5(25) ms | α (86%) | 167Os | rowspan=2|7/2− | rowspan=2| | rowspan=2| |- | β+ (14%) | 171Ir |-id=Platinum-171m | style="text-indent:1em" | 171mPt | colspan=3 style="text-indent:2em" | 412.6(10) keV | style="text-align:center" | 2010 | 901(9) ns | IT | 171Pt | 13/2+
|-id=Platinum-172 | rowspan=2|172Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 94 | rowspan=2|171.977341(11) | rowspan=2 style="text-align:center" | 1981 | rowspan=2|97.6(13) ms | α (96%) | 168Os | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β+ (4%) | 172Ir |-id=Platinum-173 | rowspan=2|173Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 95 | rowspan=2|172.976450(68) | rowspan=2 style="text-align:center" | 1966 | rowspan=2|382(2) ms | α (86%) | 169Os | rowspan=2|(5/2−) | rowspan=2| | rowspan=2| |- | β+ (14%) | 173Ir |-id=Platinum-174 | rowspan=2|174Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 96 | rowspan=2|173.972820(11) | rowspan=2 style="text-align:center" | 1966 | rowspan=2|862(8) ms | α (74.9%) | 170Os | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | β+ (25.1%) | 174Ir |-id=Platinum-175 | rowspan=2|175Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 97 | rowspan=2|174.972401(20) | rowspan=2 style="text-align:center" | 1966 | rowspan=2|2.43(4) s | α (64%) | 171Os | rowspan=2|(7/2−) | rowspan=2| | rowspan=2| |- | β+ (36%) | 175Ir |-id=Platinum-176 | rowspan=2|176Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 98 | rowspan=2|175.968938(14) | rowspan=2 style="text-align:center" | 1966 | rowspan=2|6.33(15) s | β+ (60%) | 176Ir | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (40%) | 172Os |-id=Platinum-177 | rowspan=2|177Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 99 | rowspan=2|176.968470(16) | rowspan=2 style="text-align:center" | 1966 | rowspan=2|10.0(04) s | β+ (94.3%) | 177Ir | rowspan=2|5/2− | rowspan=2| | rowspan=2| |- | α (5.7%) | 173Os |-id=Platinum-177m | style="text-indent:1em" | 177mPt | colspan=3 style="text-indent:2em" | 147.5(4) keV | style="text-align:center" | 1979 | 2.35(4) μs | IT | 177Pt | 1/2−
|-id=Platinum-178 | rowspan=2|178Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 100 | rowspan=2|177.965649(11) | rowspan=2 style="text-align:center" | 1966 | rowspan=2|20.7(7) s | β+ (92.3%) | 178Ir | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (7.7%) | 174Os |-id=Platinum-179 | rowspan=2|179Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 101 | rowspan=2|178.9653588(86) | rowspan=2 style="text-align:center" | 1966 | rowspan=2|21.2(4) s | β+ (99.76%) | 179Ir | rowspan=2|1/2− | rowspan=2| | rowspan=2| |- | α (0.24%) | 175Os |-id=Platinum-180 | rowspan=2|180Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 102 | rowspan=2|179.963038(11) | rowspan=2 style="text-align:center" | 1966 | rowspan=2|56(3) s | β+ (99.48%) | 180Ir | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (0.52%) | 176Os |-id=Platinum-181 | rowspan=2|181Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 103 | rowspan=2|180.963090(15) | rowspan=2 style="text-align:center" | 1966 | rowspan=2|52.0(22) s | β+ (99.93%) | 181Ir | rowspan=2|1/2− | rowspan=2| | rowspan=2| |- | α (0.074%) | 177Os |-id=Platinum-181m1 | style="text-indent:1em" | 181m1Pt | colspan=3 style="text-indent:2em" | 116.65(8) keV | style="text-align:center" | 1976 | >300 ns | IT | 181Pt | 7/2−
|-id=Platinum-181m2 | style="text-indent:1em" | 181m2Pt | colspan=3 style="text-indent:2em" | 275.99(10) keV | style="text-align:center" | 1990 | 99(9) ns | IT | 181Pt | (9/2+)
|-id=Platinum-182 | rowspan=2|182Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 104 | rowspan=2|181.961172(14) | rowspan=2 style="text-align:center" | 1963 | rowspan=2|2.67(12) min | β+ (99.962%) | 182Ir | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (0.038%) | 178Os |-id=Platinum-183 | rowspan=2|183Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 105 | rowspan=2|182.961596(15) | rowspan=2 style="text-align:center" | 1963 | rowspan=2|6.5(10) min | β+ (99.99%) | 183Ir | rowspan=2|1/2− | rowspan=2| | rowspan=2| |- | α (0.0096%) | 179Os |-id=Platinum-183m1 | rowspan=3 style="text-indent:1em" | 183m1Pt | rowspan=3 colspan=3 style="text-indent:2em" | 34.74(7) keV | rowspan=3 style="text-align:center" | 1979 | rowspan=3|43(5) s | β+ (96.9%) | 183Ir | rowspan=3|7/2− | rowspan=3| | rowspan=3| |- | IT (3.1%) | 183Pt |- | α ? | 179Os |-id=Platinum-183m2 | style="text-indent:1em" | 183m2Pt | colspan=3 style="text-indent:2em" | 195.90(10) keV | style="text-align:center" | 1984 | >150 ns | IT | 183Pt | 9/2+
|-id=Platinum-184 | rowspan=2|184Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 106 | rowspan=2|183.959922(16) | rowspan=2 style="text-align:center" | 1963 | rowspan=2|17.3(2) min | β+ | 184Ir | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (0.0017%) | 180Os |-id=Platinum-184m | style="text-indent:1em" | 184mPt | colspan=3 style="text-indent:2em" | 1840.3(8) keV | style="text-align:center" | 1966 | 1.01(5) ms | IT | 184Pt | 8−
|-id=Platinum-185 | rowspan=2|185Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 107 | rowspan=2|184.960614(28) | rowspan=2 style="text-align:center" | 1960 | rowspan=2|70.9(24) min | β+ | 185Ir | rowspan=2|9/2+ | rowspan=2| | rowspan=2| |- | α (0.0050%) | 181Os |-id=Platinum-185m1 | style="text-indent:1em" | 185m1Pt | colspan=3 style="text-indent:2em" | 103.41(5) keV | style="text-align:center" | 1979 | 33.0(8) min | β+ | 185Ir | 1/2−
|-id=Platinum-185m2 | style="text-indent:1em" | 185m2Pt | colspan=3 style="text-indent:2em" | 200.89(4) keV | style="text-align:center" | 1996 | 728(20) ns | IT | 185Pt | 5/2−
|-id=Platinum-186 | rowspan=2|186Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 108 | rowspan=2|185.959351(23) | rowspan=2 style="text-align:center" | 1960 | rowspan=2|2.08(5) h | β+ | 186Ir | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (1.4×10−4%) | 182Os |-id=Platinum-187 | 187Pt | style="text-align:right" | 78 | style="text-align:right" | 109 | 186.960617(26) | style="text-align:center" | 1960 | 2.35(3) h | β+ | 187Ir | 3/2−
|-id=Platinum-187m | style="text-indent:1em" | 187mPt | colspan=3 style="text-indent:2em" | 174.38(22) keV | style="text-align:center" | 1976 | 311(15) μs | IT | 187Pt | 11/2+
|-id=Platinum-188 | rowspan=2|188Pt | rowspan=2 style="text-align:right" | 78 | rowspan=2 style="text-align:right" | 110 | rowspan=2|187.9593975(57) | rowspan=2 style="text-align:center" | 1954 | rowspan=2|10.16(18) d | EC | 188Ir | rowspan=2|0+ | rowspan=2| | rowspan=2| |- | α (2.6×10−5%) | 184Os |-id=Platinum-189 | 189Pt | style="text-align:right" | 78 | style="text-align:right" | 111 | 188.960848(11) | style="text-align:center" | 1955 | 10.87(12) h | β+ | 189Ir | 3/2−
|-id=Platinum-189m1 | style="text-indent:1em" | 189m1Pt | colspan=3 style="text-indent:2em" | 172.79(6) keV | style="text-align:center" | 1969 | 464(25) ns | IT | 189Pt | 9/2−
|-id=Platinum-189m2 | style="text-indent:1em" | 189m2Pt | colspan=3 style="text-indent:2em" | 191.6(4) keV | style="text-align:center" | 1976 | 143(5) μs | IT | 189Pt | (13/2+)
|-id=Platinum-190 | 190Pt | style="text-align:right" | 78 | style="text-align:right" | 112 | 189.95994982(71) | style="text-align:center" | 1949 | 4.83(3)×1011 y | αTheorized to also undergo β+β+ decay to 190Os | 186Os | 0+ | 1.2(2)×10−4 | |-id=Platinum-191 | 191Pt | style="text-align:right" | 78 | style="text-align:right" | 113 | 190.9616763(44) | style="text-align:center" | 1948 | 2.83(2) d | EC | 191Ir | 3/2−
|-id=Platinum-191m1 | style="text-indent:1em" | 191m1Pt | colspan=3 style="text-indent:2em" | 100.663(20) keV | style="text-align:center" | 1976 | >1 μs | IT | 191Pt | 9/2−
|-id=Platinum-191m2 | style="text-indent:1em" | 191m2Pt | colspan=3 style="text-indent:2em" | 149.035(22) keV | style="text-align:center" | 1967 | 95(5) μs | IT | 191Pt | 13/2+
|-id=Platinum-192 | 192Pt | style="text-align:right" | 78 | style="text-align:right" | 114 | 191.9610427(28) | style="text-align:center" | 1935 | colspan=3 align=center|Observationally StableBelieved to undergo α decay to 188Os with a half-life over 6.0×1016 years | 0+ | 0.00782(24) | |-id=Platinum-192m | style="text-indent:1em" | 192mPt | colspan=3 style="text-indent:2em" | 2172.37(13) keV | style="text-align:center" | 1976 | 272(23) ns | IT | 192Pt | 10−
|-id=Platinum-193 | 193Pt | style="text-align:right" | 78 | style="text-align:right" | 115 | 192.9629845(15) | style="text-align:center" | 1948 | 50(6) y | EC | 193Ir | 1/2−
|-id=Platinum-193m | style="text-indent:1em" | 193mPt | colspan=3 style="text-indent:2em" | 149.78(4) keV | style="text-align:center" | 1949 | 4.33(3) d | IT | 193Pt | 13/2+
|-id=Platinum-194 | 194Pt | style="text-align:right" | 78 | style="text-align:right" | 116 | 193.96268350(53)