자연계에 존재하는 탈륨의 안정 동위 원소는 2종으로 203Tl, 205Tl이 있다. 205Tl은 넵투늄 계열의 붕괴 사슬의 최종 붕괴 생성물이다. 핵종기호 과거 명칭 Z(p) N(n) 동위 원소 질량 (u) 반감기 붕괴방식ε 전자 포획IT 이성질핵 전이 붕괴생성물 핵스핀 전형적동위 원소구성비(몰 분율) 자연적구성비변동 범위(몰 분율) 들뜬 에너지 176Tl 81 95 176.00059(21)# 5.2(+30-14) ms (3-,4-,5-) 177Tl 81 96 176.996427(27) 18(5) ms p 176Hg (1/2+) α (드묾) 173Au 177mTl 807(18) keV 230(40) µs p 176Hg (11/2-) α 173Au 178Tl 81 97 177.99490(12)# 255(10) ms α 174Au p (드묾) 177Hg 179Tl 81 98 178.99109(5) 270(30) ms α 175Au (1/2+) p (드묾) 178Hg 179mTl 860(30)# keV 1.60(16) ms α 175Au (9/2-) IT (드묾) 179Tl 180Tl 81 99 179.98991(13)# 1.5(2) s α (75%) 176Au β+ (25%) 180Hg SF (10−4%) 100Ru , 80Kr 181Tl 81 100 180.986257(10) 3.2(3) s α 177Au 1/2+# β+ 181Hg 181mTl 857(29) keV 1.7(4) ms α 177Au 9/2-# β+ 181Hg 182Tl 81 101 181.98567(8) 2.0(3) s β+ (96%) 182Hg 2-# α (4%) 178Au 182m1Tl 100(100)# keV 2.9(5) s α 178Au (7+) β+ (드묾) 182Hg 182m2Tl 600(140)# keV 10- 183Tl 81 102 182.982193(10) 6.9(7) s β+ (98%) 183Hg 1/2+# α (2%) 179Au 183m1Tl 630(17) keV 53.3(3) ms IT (99.99%) 183Tl 9/2-# α (0.01%) 179Au 183m2Tl 976.8(3) keV 1.48(10) µs (13/2+) 184Tl 81 103 183.98187(5) 9.7(6) s β+ 184Hg 2-# 184m1Tl 100(100)# keV 10# s β+ (97.9%) 184Hg 7+# α (2.1%) 180Au 184m2Tl 500(140)# keV >20 ns (10-) 185Tl 81 104 184.97879(6) 19.5(5) s α 181Au 1/2+# β+ 185Hg 185mTl 452.8(20) keV 1.93(8) s IT (99.99%) 185Tl 9/2-# α (0.01%) 181Au β+ 185Hg 186Tl 81 105 185.97833(20) 40# s β+ 186Hg (2-) α (0.006%) 182Au 186m1Tl 320(180) keV 27.5(10) s β+ 186Hg (7+) 186m2Tl 690(180) keV 2.9(2) s (10-) 187Tl 81 106 186.975906(9) ~51 s β+ 187Hg (1/2+) α (드묾) 183Au 187mTl 335(3) keV 15.60(12) s α 183Au (9/2-) IT 187Tl β+ 187Hg 188Tl 81 107 187.97601(4) 71(2) s β+ 188Hg (2-) 188m1Tl 40(30) keV 71(1) s β+ 188Hg (7+) 188m2Tl 310(30) keV 41(4) ms (9-) 189Tl 81 108 188.973588(12) 2.3(2) min β+ 189Hg (1/2+) 189mTl 257.6(13) keV 1.4(1) min β+ (96%) 189Hg (9/2-) IT (4%) 189Tl 190Tl 81 109 189.97388(5) 2.6(3) min β+ 190Hg 2(-) 190m1Tl 130(90)# keV 3.7(3) min β+ 190Hg 7(+#) 190m2Tl 290(70)# keV 750(40) µs (8-) 190m3Tl 410(70)# keV >1 µs 9- 191Tl 81 110 190.971786(8) 20# min β+ 191Hg (1/2+) 191mTl 297(7) keV 5.22(16) min β+ 191Hg 9/2(-) 192Tl 81 111 191.97223(3) 9.6(4) min β+ 192Hg (2-) 192m1Tl 160(50) keV 10.8(2) min β+ 192Hg (7+) 192m2Tl 407(54) keV 296(5) ns (8-) 193Tl 81 112 192.97067(12) 21.6(8) min β+ 193Hg 1/2(+#) 193mTl 369(4) keV 2.11(15) min IT (75%) 193Tl 9/2- β+ (25%) 193Hg 194Tl 81 113 193.97120(15) 33.0(5) min β+ 194Hg 2- α (10−7%) 190Au 194mTl 300(200)# keV 32.8(2) min β+ 194Hg (7+) 195Tl 81 114 194.969774(15) 1.16(5) h β+ 195Hg 1/2+ 195mTl 482.63(17) keV 3.6(4) s IT 195Tl 9/2- 196Tl 81 115 195.970481(13) 1.84(3) h β+ 196Hg 2- 196mTl 394.2(5) keV 1.41(2) h β+ (95.5%) 196Hg (7+) IT (4.5%) 196Tl 197Tl 81 116 196.969575(18) 2.84(4) h β+ 197Hg 1/2+ 197mTl 608.22(8) keV 540(10) ms IT 197Tl 9/2- 198Tl 81 117 197.97048(9) 5.3(5) h β+ 198Hg 2- 198m1Tl 543.5(4) keV 1.87(3) h β+ (54%) 198Hg 7+ IT (46%) 198Tl 198m2Tl 687.2(5) keV 150(40) ns (5+) 198m3Tl 742.3(4) keV 32.1(10) ms (10-)# 199Tl 81 118 198.96988(3) 7.42(8) h β+ 199Hg 1/2+ 199mTl 749.7(3) keV 28.4(2) ms IT 199Tl 9/2- 200Tl 81 119 199.970963(6) 26.1(1) h β+ 200Hg 2- 200m1Tl 753.6(2) keV 34.3(10) ms IT 200Tl 7+ 200m2Tl 762.0(2) keV 0.33(5) µs 5+ 201Tl 81 120 200.970819(16) 72.912(17) h ε 201Hg 1/2+ 201mTl 919.50(9) keV 2.035(7) ms IT 201Tl (9/2-) 202Tl 81 121 201.972106(16) 12.23(2) d β+ 202Hg 2- 202mTl 950.19(10) keV 572(7) µs 7+ 203Tl 81 122 202.9723442(14) 관측상 안정 1/2+ 0.2952(1) 0.29494-0.29528 203mTl 3400(300) keV 7.7(5) µs (25/2+) 204Tl 81 123 203.9738635(13) 3.78(2) a β- (97.1%) 204Pb 2- ε (2.9%) 204Hg 204m1Tl 1104.0(4) keV 63(2) µs (7)+ 204m2Tl 2500(500) keV 2.6(2) µs (12-) 204m3Tl 3500(500) keV 1.6(2) µs (20+) 205Tl 81 124 204.9744275(14) 관측상 안정 1/2+ 0.7048(1) 0.70472-0.70506 205m1Tl 3290.63(17) keV 2.6(2) µs 25/2+ 205m2Tl 4835.6(15) keV 235(10) ns (35/2-) 206Tl 라듐 E 81 125 205.9761103(15) 4.200(17) min β- 206Pb 0- 미량 206mTl 2643.11(19) keV 3.74(3) min IT 206Tl (12-) 207Tl 악티늄 C 81 126 206.977419(6) 4.77(2) min β- 207Pb 1/2+ 미량 207mTl 1348.1(3) keV 1.33(11) s IT (99.9%) 207Tl 11/2- β- (0.1%) 207Pb 208Tl 토륨 C 81 127 207.9820187(21) 3.053(4) min β- 208Pb 5(+) 미량 209Tl 81 128 208.985359(8) 2.161(7) min β- 209Pb (1/2+) 210Tl 라듐 C″ 81 129 209.990074(12) 1.30(3) min β- (99.991%) 210Pb (5+)# 미량 β-, n (0.009%) 209Pb 211Tl 81 130 210.99348(22)# 1# min>300 ns 1/2+# 212Tl 81 131 211.99823(32)# 30# s>300 ns 5+# 동위 원소 분류:원소별 동위 원소 목록