Isotopes of mercury

Isotopes of mercury (₈₀Hg)
Standard atomic weight Ar°(Hg)
	200.592±0.003; 200.59±0.01 (abridged);
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Last updated October 14, 2024

There are seven stable isotopes of mercury (₈₀Hg) with ²⁰²Hg being the most abundant (29.86%). The longest-lived radioisotopes are ¹⁹⁴Hg with a half-life of 444 years, and ²⁰³Hg with a half-life of 46.612 days. Most of the remaining 40 radioisotopes have half-lives that are less than a day. ¹⁹⁹Hg and ²⁰¹Hg are the most often studied NMR-active nuclei, having spin quantum numbers of 1/2 and 3/2 respectively. All isotopes of mercury are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed. These isotopes are predicted to undergo either alpha decay or double beta decay.

List of isotopes

Nuclide ^{[n 1]}	Z	N	Isotopic mass (Da)^[4] ^{[n 2]}^{[n 3]}	Half-life ^[1] ^{[n 4]}	Decay mode ^[1] ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity ^[1] ^{[n 7]}^{[n 4]}	Natural abundance (mole fraction)
Nuclide ^{[n 1]}	Excitation energy^{[n 4]}			Half-life ^[1] ^{[n 4]}	Decay mode ^[1] ^{[n 5]}	Daughter isotope ^{[n 6]}	Spin and parity ^[1] ^{[n 7]}^{[n 4]}	Normal proportion^[1]	Range of variation
¹⁷⁰Hg	80	90	170.00581(32)#	310(250) μs	α	¹⁶⁶Pt	0+
¹⁷¹Hg	80	91	171.00359(33)#	70(30) μs	α	¹⁶⁷Pt	3/2−#
¹⁷²Hg	80	92	171.99886(16)	231(9) μs	α	¹⁶⁸Pt	0+
¹⁷³Hg	80	93	172.99714(22)#	800(80) μs	α	¹⁶⁹Pt	(7/2−)
¹⁷⁴Hg	80	94	173.992871(21)	2.0(4) ms	α	¹⁷⁰Pt	0+
¹⁷⁵Hg	80	95	174.99144(9)	10.2(3) ms	α	¹⁷¹Pt	(7/2−)
^175mHg	494(2) keV			340(30) ns	IT	¹⁷⁵Hg	(13/2+)
¹⁷⁶Hg	80	96	175.987349(12)	20.3(14) ms	α (90%)	¹⁷²Pt	0+
¹⁷⁶Hg	80	96	175.987349(12)	20.3(14) ms	β⁺ (10%)	¹⁷⁶Au	0+
¹⁷⁷Hg	80	97	176.98628(9)	117(7) ms	α	¹⁷³Pt	7/2−
^177mHg	323.2(13) keV			1.50(15) μs	IT	¹⁷⁷Hg	13/2+
¹⁷⁸Hg	80	98	177.982485(12)	266.5(24) ms	α (89%)	¹⁷⁴Pt	0+
¹⁷⁸Hg	80	98	177.982485(12)	266.5(24) ms	β⁺ (11%)	¹⁷⁸Au	0+
¹⁷⁹Hg	80	99	178.98182(3)	1.05(3) s	α (75%)	¹⁷⁵Pt	7/2−
					β⁺ (25%)	¹⁷⁹Au
					β⁺, p (0.15%)	¹⁷⁸Pt
^179mHg	171.4(4) keV			6.4(9) μs	IT	¹⁷⁹Hg	13/2+
¹⁸⁰Hg	80	100	179.978260(14)	2.59(1) s	β⁺ (52%)	¹⁸⁰Au	0+
¹⁸⁰Hg	80	100	179.978260(14)	2.59(1) s	α (48%)	¹⁷⁶Pt	0+
¹⁸¹Hg	80	101	180.977819(17)	3.6(1) s	β⁺ (73%)	¹⁸¹Au	1/2−
					α (27%)	¹⁷⁷Pt
					β⁺, p (0.014%)	¹⁸⁰Pt
					β⁺, α (9×10⁻⁶%)	¹⁷⁷Ir
^181mHg	210(50) keV			480(20) μs	IT	¹⁸¹Hg	13/2+
¹⁸²Hg	80	102	181.974689(11)	10.83(6) s	β⁺ (86.2%)	¹⁸²Au	0+
					α (13.8%)	¹⁷⁸Pt
					β⁺, p (<1×10⁻⁵%)	¹⁸¹Pt
¹⁸³Hg	80	103	182.974445(8)	9.4(7) s	β⁺ (88.3%)	¹⁸³Au	1/2−
					α (11.7%)	¹⁷⁹Pt
					β⁺, p (2.6×10⁻⁴%)	¹⁸²Pt
^183mHg	204(14) keV			>5# μs			13/2+#
¹⁸⁴Hg	80	104	183.971718(10)	30.87(26) s	β⁺ (98.89%)	¹⁸⁴Au	0+
¹⁸⁴Hg	80	104	183.971718(10)	30.87(26) s	α (1.11%)	¹⁸⁰Pt	0+
¹⁸⁵Hg	80	105	184.971891(15)	49.1(10) s	β⁺ (94%)	¹⁸⁵Au	1/2−
¹⁸⁵Hg	80	105	184.971891(15)	49.1(10) s	α (6%)	¹⁸¹Pt	1/2−
^185mHg	103.7(4) keV			21.6(15) s	IT (54%)	¹⁸⁵Hg	13/2+
					β⁺ (46%)	¹⁸⁵Au
					α (0.03%)	¹⁸¹Pt
¹⁸⁶Hg	80	106	185.969362(13)	1.38(6) min	β⁺ (99.98%)	¹⁸⁶Au	0+
¹⁸⁶Hg	80	106	185.969362(13)	1.38(6) min	α (0.016%)	¹⁸²Pt	0+
^186mHg	2217.3(4) keV			82(5) μs	IT	¹⁸⁶Hg	(8−)
¹⁸⁷Hg	80	107	186.969814(14)	1.9(3) min	β⁺	¹⁸⁷Au	3/2−
^187mHg	58(14) keV			2.4(3) min	β⁺	¹⁸⁷Au	13/2+
¹⁸⁸Hg	80	108	187.967581(7)	3.25(15) min	β⁺	¹⁸⁸Au	0+
¹⁸⁸Hg	80	108	187.967581(7)	3.25(15) min	α (3.7×10⁻⁵%)	¹⁸⁴Pt	0+
^188mHg	2724.1(4) keV			142(14) ns	IT	¹⁸⁸Hg	12+
¹⁸⁹Hg	80	109	188.96819(3)	7.6(2) min	β⁺	¹⁸⁹Au	3/2−
^189mHg	80(30) keV			8.6(2) min	β⁺	¹⁸⁹Au	13/2+
¹⁹⁰Hg	80	110	189.966322(17)	20.0(5) min	β⁺	¹⁹⁰Au	0+
¹⁹¹Hg	80	111	190.967158(24)	49(10) min	β⁺	¹⁹¹Au	3/2−
^191mHg	128(22) keV			50.8(15) min	β⁺	¹⁹¹Au	13/2+
¹⁹²Hg	80	112	191.965634(17)	4.85(20) h	EC	¹⁹²Au	0+
¹⁹³Hg	80	113	192.966653(17)	3.80(15) h	β⁺	¹⁹³Au	3/2−
^193mHg	140.76(5) keV			11.8(2) h	β⁺ (92.8%)	¹⁹³Au	13/2+
^193mHg	140.76(5) keV			11.8(2) h	IT (7.2%)	¹⁹³Hg	13/2+
¹⁹⁴Hg	80	114	193.965449(3)	447(28) y	EC	¹⁹⁴Au	0+
¹⁹⁵Hg	80	115	194.966706(25)	10.69(16) h	β⁺	¹⁹⁵Au	1/2−
^195mHg	176.07(4) keV			41.60(19) h	IT (54.2%)	¹⁹⁵Hg	13/2+
^195mHg	176.07(4) keV			41.60(19) h	β⁺ (45.8%)	¹⁹⁵Au	13/2+
¹⁹⁶Hg	80	116	195.965833(3)	Observationally Stable ^{[n 8]}			0+	0.0015(1)
¹⁹⁷Hg	80	117	196.967214(3)	64.93(7) h	EC	¹⁹⁷Au	1/2−
^197mHg	298.93(8) keV			23.82(4) h	IT (94.68%)	¹⁹⁷Hg	13/2+
^197mHg	298.93(8) keV			23.82(4) h	EC (5.32%)	¹⁹⁷Au	13/2+
¹⁹⁸Hg	80	118	197.9667692(5)	Observationally Stable^{[n 9]}			0+	0.1004(3)
¹⁹⁹Hg	80	119	198.9682810(6)	Observationally Stable^{[n 10]}			1/2−	0.1694(12)
^199mHg	532.48(10) keV			42.67(9) min	IT	¹⁹⁹Hg	13/2+
²⁰⁰Hg	80	120	199.9683269(6)	Observationally Stable^{[n 11]}			0+	0.2314(9)
²⁰¹Hg	80	121	200.9703031(8)	Observationally Stable^{[n 12]}			3/2−	0.1317(9)
^201mHg	766.22(15) keV			94.0(20) μs	IT	²⁰¹Hg	13/2+
²⁰²Hg	80	122	201.9706436(8)	Observationally Stable^{[n 13]}			0+	0.2974(13)
²⁰³Hg	80	123	202.9728724(18)	46.610(10) d	β⁻	²⁰³Tl	5/2−
^203m1Hg	933.14(23) keV			22.1(10) μs	IT	²⁰³Hg	(13/2+)
^203m2Hg	8281.3(5) keV			146(30) ns	IT	²⁰³Hg	(53/2+)
²⁰⁴Hg	80	124	203.9734940(5)	Observationally Stable^{[n 14]}			0+	0.0682(4)
^204mHg	7226.08(17) keV			~485 ns	IT	²⁰⁴Hg	22+
²⁰⁵Hg	80	125	204.976073(4)	5.14(9) min	β⁻	²⁰⁵Tl	1/2−
^205m1Hg	1556.4(3) keV			1.09(4) ms	IT	²⁰⁵Hg	13/2+
^205m2Hg	3316.6(8) keV			5.89(18) μs	IT	²⁰⁵Hg	(23/2−)
²⁰⁶Hg	80	126	205.977514(22)	8.32(7) min	β⁻	²⁰⁶Tl	0+	Trace^{[n 15]}
^206m1Hg	2102.4(3) keV			2.088(17) μs	IT	²⁰⁶Hg	5−
^206m2Hg	3722.3(10) keV			106(3) ns	IT	²⁰⁶Hg	(10+)
²⁰⁷Hg	80	127	206.98230(3)	2.9(2) min	β⁻	²⁰⁷Tl	9/2+
²⁰⁸Hg	80	128	207.98576(3)	135(10) s	β⁻	²⁰⁸Tl	0+
^208mHg	1338(24) keV			99(14) ns	IT	²⁰⁸Hg	(8+)
²⁰⁹Hg	80	129	208.99076(16)#	6.3(11) s	β⁻	²⁰⁹Tl	9/2+#
²¹⁰Hg	80	130	209.99431(22)#	64(12) s	β⁻ (97.8%)	²¹⁰Tl	0+
²¹⁰Hg	80	130	209.99431(22)#	64(12) s	β⁻, n (2.2%)	²⁰⁹Tl	0+
^210m1Hg	663(2) keV			2.1(7) μs	IT	²¹⁰Hg	(3−)
^210m2Hg	1406(23) keV			2(1) μs	IT	²¹⁰Hg	8+#
²¹¹Hg	80	131	210.99958(22)#	26.4(81) s	β⁻ (93.7%)	²¹¹Tl	9/2+#
²¹¹Hg	80	131	210.99958(22)#	26.4(81) s	β⁻, n (6.3%)	²¹⁰Tl	9/2+#
²¹²Hg	80	132	212.00324(32)#	30# s [>300 ns]			0+
²¹³Hg	80	133	213.00880(32)#	15# s [>300 ns]			9/2+#
²¹⁴Hg	80	134	214.01264(43)#	8# s [>300 ns]			0+
²¹⁵Hg	80	135	215.01837(43)#	600# ms [>300 ns]			9/2+#
²¹⁶Hg	80	136	216.02246(43)#	2# s [>300 ns]			0+
This table header & footer: view

↑ ^mHg – Excited nuclear isomer.
↑ ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
↑ # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
↑ Modes of decay:
EC: Electron capture
IT: Isomeric transition
↑ Bold symbol as daughter – Daughter product is stable.
↑ ( ) spin value – Indicates spin with weak assignment arguments.
↑ Believed to undergo β⁺β⁺ decay to ¹⁹⁶Pt with a half-life over 2.5×10¹⁸ years; also theorized to undergo α decay to ¹⁹²Pt
↑ Believed to undergo α decay to ¹⁹⁴Pt
↑ Believed to undergo α decay to ¹⁹⁵Pt
↑ Believed to undergo α decay to ¹⁹⁶Pt
↑ Believed to undergo α decay to ¹⁹⁷Pt
↑ Believed to undergo α decay to ¹⁹⁸Pt
↑ Believed to undergo β⁻β⁻ decay to ²⁰⁴Pb
↑ Intermediate decay product of ²³⁸U

Related Research Articles

Bismuth (₈₃Bi) has 41 known isotopes, ranging from ¹⁸⁴Bi to ²²⁴Bi. Bismuth has no stable isotopes, but does have one very long-lived isotope; thus, the standard atomic weight can be given as 208.98040(1). Although bismuth-209 is now known to be radioactive, it has classically been considered to be a stable isotope because it has a half-life of approximately 2.01×10¹⁹ years, which is more than a billion times the age of the universe. Besides ²⁰⁹Bi, the most stable bismuth radioisotopes are ^210mBi with a half-life of 3.04 million years, ²⁰⁸Bi with a half-life of 368,000 years and ²⁰⁷Bi, with a half-life of 32.9 years, none of which occurs in nature. All other isotopes have half-lives under 1 year, most under a day. Of naturally occurring radioisotopes, the most stable is radiogenic ²¹⁰Bi with a half-life of 5.012 days. ^210mBi is unusual for being a nuclear isomer with a half-life multiple orders of magnitude longer than that of the ground state.

Thallium (₈₁Tl) has 41 isotopes with atomic masses that range from 176 to 216. ²⁰³Tl and ²⁰⁵Tl are the only stable isotopes and ²⁰⁴Tl is the most stable radioisotope with a half-life of 3.78 years. ²⁰⁷Tl, with a half-life of 4.77 minutes, has the longest half-life of naturally occurring Tl radioisotopes. All isotopes of thallium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.

Gold (₇₉Au) has one stable isotope, ¹⁹⁷Au, and 40 radioisotopes, with ¹⁹⁵Au being the most stable with a half-life of 186 days. Gold is currently considered the heaviest monoisotopic element. Bismuth formerly held that distinction until alpha-decay of the ²⁰⁹Bi isotope was observed. All isotopes of gold are either radioactive or, in the case of ¹⁹⁷Au, observationally stable, meaning that ¹⁹⁷Au is predicted to be radioactive but no actual decay has been observed.

Naturally occurring platinum (₇₈Pt) consists of five stable isotopes (¹⁹²Pt, ¹⁹⁴Pt, ¹⁹⁵Pt, ¹⁹⁶Pt, ¹⁹⁸Pt) and one very long-lived (half-life 4.83×10¹¹ years) radioisotope (¹⁹⁰Pt). There are also 34 known synthetic radioisotopes, the longest-lived of which is ¹⁹³Pt with a half-life of 50 years. All other isotopes have half-lives under a year, most under a day. 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.

There are two natural isotopes of iridium (₇₇Ir), and 37 radioisotopes, the most stable radioisotope being ¹⁹²Ir with a half-life of 73.83 days, and many nuclear isomers, the most stable of which is ^192m2Ir with a half-life of 241 years. All other isomers have half-lives under a year, most under a day. All isotopes of iridium are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed.

Natural hafnium (₇₂Hf) consists of five observationally stable isotopes (¹⁷⁶Hf, ¹⁷⁷Hf, ¹⁷⁸Hf, ¹⁷⁹Hf, and ¹⁸⁰Hf) and one very long-lived radioisotope, ¹⁷⁴Hf, with a half-life of 7.0×10¹⁶ years. In addition, there are 34 known synthetic radioisotopes, the most stable of which is ¹⁸²Hf with a half-life of 8.9×10⁶ years. This extinct radionuclide is used in hafnium–tungsten dating to study the chronology of planetary differentiation.

Naturally occurring ytterbium (₇₀Yb) is composed of seven stable isotopes: ¹⁶⁸Yb, ¹⁷⁰Yb–¹⁷⁴Yb, and ¹⁷⁶Yb, with ¹⁷⁴Yb being the most abundant. 30 radioisotopes have been characterized, with the most stable being ¹⁶⁹Yb with a half-life of 32.014 days, ¹⁷⁵Yb with a half-life of 4.185 days, and ¹⁶⁶Yb with a half-life of 56.7 hours. All of the remaining radioactive isotopes have half-lives that are less than 2 hours, and the majority of these have half-lives that are less than 20 minutes. This element also has 18 meta states, with the most stable being ^169mYb.

Naturally occurring erbium (₆₈Er) is composed of six stable isotopes, with ¹⁶⁶Er being the most abundant. Thirty-nine radioisotopes have been characterized with between 74 and 112 neutrons, or 142 to 180 nucleons, with the most stable being ¹⁶⁹Er with a half-life of 9.4 days, ¹⁷²Er with a half-life of 49.3 hours, ¹⁶⁰Er with a half-life of 28.58 hours, ¹⁶⁵Er with a half-life of 10.36 hours, and ¹⁷¹Er with a half-life of 7.516 hours. All of the remaining radioactive isotopes have half-lives that are less than 3.5 hours, and the majority of these have half-lives that are less than 4 minutes. This element also has numerous meta states, with the most stable being ^167mEr.

Natural holmium (₆₇Ho) contains one observationally stable isotope, ¹⁶⁵Ho. The below table lists 36 isotopes spanning ¹⁴⁰Ho through ¹⁷⁵Ho as well as 33 nuclear isomers. Among the known synthetic radioactive isotopes; the most stable one is ¹⁶³Ho, with a half-life of 4,570 years. All other radioisotopes have half-lives not greater than 1.117 days in their ground states, and most have half-lives under 3 hours.

Naturally occurring dysprosium (₆₆Dy) is composed of 7 stable isotopes, ¹⁵⁶Dy, ¹⁵⁸Dy, ¹⁶⁰Dy, ¹⁶¹Dy, ¹⁶²Dy, ¹⁶³Dy and ¹⁶⁴Dy, with ¹⁶⁴Dy being the most abundant. Twenty-nine radioisotopes have been characterized, with the most stable being ¹⁵⁴Dy with a half-life of 1.4 million years, ¹⁵⁹Dy with a half-life of 144.4 days, and ¹⁶⁶Dy with a half-life of 81.6 hours. All of the remaining radioactive isotopes have half-lives that are less than 10 hours, and the majority of these have half-lives that are less than 30 seconds. This element also has 12 meta states, with the most stable being ^165mDy, ^147mDy and ^145mDy.

Naturally occurring gadolinium (₆₄Gd) is composed of 6 stable isotopes, ¹⁵⁴Gd, ¹⁵⁵Gd, ¹⁵⁶Gd, ¹⁵⁷Gd, ¹⁵⁸Gd and ¹⁶⁰Gd, and 1 radioisotope, ¹⁵²Gd, with ¹⁵⁸Gd being the most abundant (24.84% natural abundance). The predicted double beta decay of ¹⁶⁰Gd has never been observed; only a lower limit on its half-life of more than 1.3×10²¹ years has been set experimentally.

Naturally occurring neodymium (₆₀Nd) is composed of 5 stable isotopes, ¹⁴²Nd, ¹⁴³Nd, ¹⁴⁵Nd, ¹⁴⁶Nd and ¹⁴⁸Nd, with ¹⁴²Nd being the most abundant (27.2% natural abundance), and 2 long-lived radioisotopes, ¹⁴⁴Nd and ¹⁵⁰Nd. In all, 33 radioisotopes of neodymium have been characterized up to now, with the most stable being naturally occurring isotopes ¹⁴⁴Nd (alpha decay, a half-life (t_1/2) of 2.29×10¹⁵ years) and ¹⁵⁰Nd (double beta decay, t_1/2 of 7×10¹⁸ years), and for practical purposes they can be considered to be stable as well. All of the remaining radioactive isotopes have half-lives that are less than 12 days, and the majority of these have half-lives that are less than 70 seconds; the most stable artificial isotope is ¹⁴⁷Nd with a half-life of 10.98 days. This element also has 13 known meta states with the most stable being ^139mNd (t_1/2 5.5 hours), ^135mNd (t_1/2 5.5 minutes) and ^133m1Nd (t_1/2 ~70 seconds).

Naturally occurring cerium (₅₈Ce) is composed of 4 stable isotopes: ¹³⁶Ce, ¹³⁸Ce, ¹⁴⁰Ce, and ¹⁴²Ce, with ¹⁴⁰Ce being the most abundant and the only one theoretically stable; ¹³⁶Ce, ¹³⁸Ce, and ¹⁴²Ce are predicted to undergo double beta decay but this process has never been observed. There are 35 radioisotopes that have been characterized, with the most stable being ¹⁴⁴Ce, with a half-life of 284.893 days; ¹³⁹Ce, with a half-life of 137.640 days and ¹⁴¹Ce, with a half-life of 32.501 days. All of the remaining radioactive isotopes have half-lives that are less than 4 days and the majority of these have half-lives that are less than 10 minutes. This element also has 10 meta states.

Naturally occurring barium (₅₆Ba) is a mix of six stable isotopes and one very long-lived radioactive primordial isotope, barium-130, identified as being unstable by geochemical means (from analysis of the presence of its daughter xenon-130 in rocks) in 2001. This nuclide decays by double electron capture (absorbing two electrons and emitting two neutrinos), with a half-life of (0.5–2.7)×10²¹ years (about 10¹¹ times the age of the universe).

Antimony (₅₁Sb) occurs in two stable isotopes, ¹²¹Sb and ¹²³Sb. There are 37 artificial radioactive isotopes, the longest-lived of which are ¹²⁵Sb, with a half-life of 2.75856 years; ¹²⁴Sb, with a half-life of 60.2 days; and ¹²⁶Sb, with a half-life of 12.35 days. All other isotopes have half-lives less than 4 days, most less than an hour. There are also many isomers, the longest-lived of which is ^120m1Sb with a half-life of 5.76 days.

Tin (₅₀Sn) is the element with the greatest number of stable isotopes. This is probably related to the fact that 50 is a "magic number" of protons. In addition, twenty-nine unstable tin isotopes are known, including tin-100 (¹⁰⁰Sn) and tin-132 (¹³²Sn), which are both "doubly magic". The longest-lived tin radioisotope is tin-126 (¹²⁶Sn), with a half-life of 230,000 years. The other 28 radioisotopes have half-lives of less than a year.

Naturally occurring silver (₄₇Ag) is composed of the two stable isotopes ¹⁰⁷Ag and ¹⁰⁹Ag in almost equal proportions, with ¹⁰⁷Ag being slightly more abundant. Notably, silver is the only element with all stable istopes having nuclear spins of 1/2. Thus both ¹⁰⁷Ag and ¹⁰⁹Ag nuclei produce narrow lines in nuclear magnetic resonance spectra.

Bromine (₃₅Br) has two stable isotopes, ⁷⁹Br and ⁸¹Br, and 35 known radioisotopes, the most stable of which is ⁷⁷Br, with a half-life of 57.036 hours.

Naturally occurring zinc (₃₀Zn) is composed of the 5 stable isotopes ⁶⁴Zn, ⁶⁶Zn, ⁶⁷Zn, ⁶⁸Zn, and ⁷⁰Zn with ⁶⁴Zn being the most abundant. Twenty-eight radioisotopes have been characterised with the most stable being ⁶⁵Zn with a half-life of 244.26 days, and then ⁷²Zn with a half-life of 46.5 hours. All of the remaining radioactive isotopes have half-lives that are less than 14 hours and the majority of these have half-lives that are less than 1 second. This element also has 10 meta states.

Naturally occurring scandium (₂₁Sc) is composed of one stable isotope, ⁴⁵Sc. Twenty-seven radioisotopes have been characterized, with the most stable being ⁴⁶Sc with a half-life of 83.8 days, ⁴⁷Sc with a half-life of 3.35 days, and ⁴⁸Sc with a half-life of 43.7 hours and ⁴⁴Sc with a half-life of 3.97 hours. All the remaining isotopes have half-lives that are less than four hours, and the majority of these have half-lives that are less than two minutes, the least stable being proton unbound ³⁹Sc with a half-life shorter than 300 nanoseconds. This element also has 13 meta states with the most stable being ^44m2Sc.

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↑ "Standard Atomic Weights: Mercury". CIAAW. 2011.
↑ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
↑ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.

Isotopic compositions and standard atomic masses from:
- de Laeter, John Robert; Böhlke, John Karl; De Bièvre, Paul; Hidaka, Hiroshi; Peiser, H. Steffen; Rosman, Kevin J. R.; Taylor, Philip D. P. (2003). "Atomic weights of the elements. Review 2000 (IUPAC Technical Report)". Pure and Applied Chemistry . 75 (6): 683–800. doi: 10.1351/pac200375060683 .
- Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry . 78 (11): 2051–2066. doi: 10.1351/pac200678112051 .

"News & Notices: Standard Atomic Weights Revised". International Union of Pure and Applied Chemistry. 19 October 2005.
Half-life, spin, and isomer data selected from the following sources.
- Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
- Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
- National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory.
- Holden, Norman E. (2004). "11. Table of the Isotopes". In Lide, David R. (ed.). CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

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[4] Hg – Excited nuclear isomer.

[6] ( ) – Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.

[TMS-7] # – Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).

[TNN-8] 1 2 3 # – Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).

[9] Modes of decay:
EC: Electron capture
IT: Isomeric transition

[10] Bold symbol as daughter – Daughter product is stable.

[11] ( ) spin value – Indicates spin with weak assignment arguments.

[12] Believed to undergo β⁺β⁺ decay to ¹⁹⁶Pt with a half-life over 2.5×10¹⁸ years; also theorized to undergo α decay to ¹⁹²Pt

[13] Believed to undergo α decay to ¹⁹⁴Pt

[14] Believed to undergo α decay to ¹⁹⁵Pt

[15] Believed to undergo α decay to ¹⁹⁶Pt

[16] Believed to undergo α decay to ¹⁹⁷Pt

[17] Believed to undergo α decay to ¹⁹⁸Pt

[18] Believed to undergo β⁻β⁻ decay to ²⁰⁴Pb

[Th-19] Intermediate decay product of ²³⁸U

[NUBASE2020-1] 1 2 3 4 5 Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

[2] "Standard Atomic Weights: Mercury". CIAAW. 2011.

[CIAAW2021-3] Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.

[AME2020_II-5] Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3): 030003. doi:10.1088/1674-1137/abddaf.

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