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Bromine
Phase of Berkelium
Sb (Symbol of Antimony)
15 (Atomic Number of Phosphorus)
Atomic Mass of Praseodymium in lb

At

Astatine

Properties

Isotopes

Electrons

39 known isotopes (0 stable, 39 radioactive)

Show stable only

¹⁹¹At

Mass

191.004148 u

Abundance

—

Half-life

1.7 milliseconds

Spin/Parity

(1/2+)

Decay Mode(s)

α (100%)

¹⁹²At

Mass

192.003141 u

Abundance

—

Half-life

88 milliseconds

Spin/Parity

(9- 10-)

Decay Mode(s)

α (100%)

¹⁹³At

Mass

192.999928 u

Abundance

—

Half-life

28 milliseconds

Spin/Parity

(1/2+)

Decay Mode(s)

α (100%)

¹⁹⁴At

Mass

193.999231 u

Abundance

—

Half-life

286 milliseconds

Spin/Parity

(4- 5-)

Decay Mode(s)

α (100%), SF+EC+B+ (0.8%)

¹⁹⁵At

Mass

194.996274 u

Abundance

—

Half-life

290 milliseconds

Spin/Parity

(1/2+)

Decay Mode(s)

α (100%)

¹⁹⁶At

Mass

195.995799 u

Abundance

—

Half-life

0.388 seconds

Spin/Parity

(3+)

Decay Mode(s)

α (95.1%), EC/β⁺ (4.9%)

¹⁹⁷At

Mass

196.993177 u

Abundance

—

Half-life

0.388 seconds

Spin/Parity

(9/2-)

Decay Mode(s)

α (96.1%), EC/β⁺ (3.9%)

¹⁹⁸At

Mass

197.992798 u

Abundance

—

Half-life

4.2 seconds

Spin/Parity

(3+)

Decay Mode(s)

α (90%), EC/β⁺ (10%)

¹⁹⁹At

Mass

198.990528 u

Abundance

—

Half-life

7.03 seconds

Spin/Parity

(9/2-)

Decay Mode(s)

α (90%), EC/β⁺ (10%)

²⁰⁰At

Mass

199.990351 u

Abundance

—

Half-life

43 seconds

Spin/Parity

(3+)

Decay Mode(s)

α (52%), EC/β⁺ (48%)

²⁰¹At

Mass

200.988417 u

Abundance

—

Half-life

87.6 seconds

Spin/Parity

9/2-

Decay Mode(s)

α (71%), EC/β⁺ (29%)

²⁰²At

Mass

201.988626 u

Abundance

—

Half-life

184 seconds

Spin/Parity

(2+ 3+)

Decay Mode(s)

EC/β⁺ (63%), α (37%)

²⁰³At

Mass

202.986943 u

Abundance

—

Half-life

7.4 m

Spin/Parity

9/2-

Decay Mode(s)

EC/β⁺ (69%), α (31%)

²⁰⁴At

Mass

203.987251 u

Abundance

—

Half-life

9.12 m

Spin/Parity

Decay Mode(s)

EC/β⁺ (96.09%), α (3.91%)

²⁰⁵At

Mass

204.986061 u

Abundance

—

Half-life

26.9 m

Spin/Parity

9/2-

Decay Mode(s)

EC/β⁺ (90%), α (10%)

²⁰⁶At

Mass

205.986646 u

Abundance

—

Half-life

30.6 m

Spin/Parity

(5)+

Decay Mode(s)

EC/β⁺ (99.1%), α (0.9%)

²⁰⁷At

Mass

206.985800 u

Abundance

—

Half-life

1.81 h

Spin/Parity

9/2-

Decay Mode(s)

EC/β⁺ (91.4%), α (8.6%)

²⁰⁸At

Mass

207.986613 u

Abundance

—

Half-life

1.63 h

Spin/Parity

Decay Mode(s)

EC/β⁺ (99.45%), α (0.55%)

²⁰⁹At

Mass

208.986169 u

Abundance

—

Half-life

5.42 h

Spin/Parity

9/2-

Decay Mode(s)

EC/β⁺ (95.9%), α (4.1%)

²¹⁰At

Mass

209.987147 u

Abundance

—

Half-life

8.1 h

Spin/Parity

(5)+

Decay Mode(s)

EC/β⁺ (99.825%), α (0.175%)

²¹¹At

Mass

210.987496 u

Abundance

—

Half-life

7.214 h

Spin/Parity

9/2-

Decay Mode(s)

Electron capture (58.2%), α (41.8%)

²¹²At

Mass

211.990737 u

Abundance

—

Half-life

0.314 seconds

Spin/Parity

(1-)

Decay Mode(s)

α (100%)

²¹³At

Mass

212.992937 u

Abundance

—

Half-life

125 nanoseconds

Spin/Parity

9/2-

Decay Mode(s)

α (100%)

²¹⁴At

Mass

213.996372 u

Abundance

—

Half-life

558 nanoseconds

Spin/Parity

Decay Mode(s)

α (100%)

²¹⁵At

Mass

214.998651 u

Abundance

—

Half-life

0.10 milliseconds

Spin/Parity

9/2-

Decay Mode(s)

α (100%)

²¹⁶At

Mass

216.002423 u

Abundance

—

Half-life

0.30 milliseconds

Spin/Parity

Decay Mode(s)

α (100%), β⁻ (0.006%), Electron capture (3e-7%)

²¹⁷At

Mass

217.004718 u

Abundance

—

Half-life

32.6 milliseconds

Spin/Parity

9/2-

Decay Mode(s)

α (99.993%), β⁻ (0.007%)

²¹⁸At

Mass

218.008696 u

Abundance

—

Half-life

1.28 seconds

Spin/Parity

(3- 2-)

Decay Mode(s)

α (99.95%), β⁻ (0.05%)

²¹⁹At

Mass

219.011161 u

Abundance

—

Half-life

56 seconds

Spin/Parity

(9/2-)

Decay Mode(s)

α (93.6%), β⁻ (6.4%)

²²⁰At

Mass

220.015433 u

Abundance

—

Half-life

3.71 m

Spin/Parity

Decay Mode(s)

β⁻ (92%), α (8%)

²²¹At

Mass

221.018017 u

Abundance

—

Half-life

2.3 m

Spin/Parity

—

Decay Mode(s)

β⁻ (100%)

²²²At

Mass

222.022494 u

Abundance

—

Half-life

54 seconds

Spin/Parity

—

Decay Mode(s)

β⁻ (100%)

²²³At

Mass

223.025151 u

Abundance

—

Half-life

50 seconds

Spin/Parity

—

Decay Mode(s)

β⁻ (100%)

²²⁴At

Mass

224.029749 u

Abundance

—

Half-life

1.3 m

Spin/Parity

—

Decay Mode(s)

Unknown

²²⁵At

Mass

225.032528 u

Abundance

—

Half-life

300 nanoseconds

Spin/Parity

—

Decay Mode(s)

Unknown

²²⁶At

Mass

226.037209 u

Abundance

—

Half-life

300 nanoseconds

Spin/Parity

—

Decay Mode(s)

Unknown

²²⁷At

Mass

227.040183 u

Abundance

—

Half-life

300 nanoseconds

Spin/Parity

—

Decay Mode(s)

Unknown

²²⁸At

Mass

228.044960 u

Abundance

—

Half-life

300 nanoseconds

Spin/Parity

—

Decay Mode(s)

Unknown

²²⁹At

Mass

229.048191 u

Abundance

—

Half-life

300 nanoseconds

Spin/Parity

—

Decay Mode(s)

Unknown

Decay mode abbreviations:

β⁻ = Beta minus decay, β⁺ = Beta plus decay, EC = Electron capture, α = Alpha decay

n = Neutron emission, p = Proton emission, SF = Spontaneous fission, IT = Isomeric transition

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