Element: Polonium

General data

Element name	Polonium
Chemical symbol	Po
Atomic number Z	84
Year discovered	1898
Standard state (25°C)	Solid
Category	Metalloid
Block	p
Atomic mass	[209]
CPK color	#AB5C00

Physical properties

Melting point	527 K (254 °C)
Boiling point	1235 K (962 °C)
Density	9.32 g/cm³

Energy properties

First ionization energy	8.417 eV
Electron affinity	1.9 eV

Atomic structure

Protons	84 (Atomic number)
Neutrons (Po-209, longest-lived isotope)	125
Electrons	84
Electron configuration	[Xe] 6s² 4f¹⁴ 5d¹⁰ 6p⁴
Oxidation states	+4, +2
Electronegativity (Pauling)	2
Atomic radius (van der Waals)	197 pm

Ionization energies - NIST ASD (84 states)

State	Charge	Ioniz. energy (eV)	Type
Po I	0+	8.41807 ± 0.000004	measured
Po II	1+	19.3 ± 1.7	semi-empirical
Po III	2+	27.3 ± 0.7	semi-empirical
Po IV	3+	36 ± 1.7	calculated
Po V	4+	57 ± 1.9	calculated
Po VI	5+	69.1 ± 2	calculated
Po VII	6+	108 ± 2	calculated
Po VIII	7+	125 ± 2.1	calculated
Po IX	8+	146.1 ± 2.2	calculated
Po X	9+	166 ± 2.2	calculated
Po XI	10+	186 ± 2.4	calculated
Po XII	11+	209 ± 2.5	calculated
Po XIII	12+	235 ± 3	calculated
Po XIV	13+	257 ± 3	calculated
Po XV	14+	281 ± 3	calculated
Po XVI	15+	304 ± 3	calculated
Po XVII	16+	416 ± 21	calculated
Po XVIII	17+	444 ± 22	calculated
Po XIX	18+	473 ± 24	calculated
Po XX	19+	502 ± 25	calculated
Po XXI	20+	560 ± 30	calculated
Po XXII	21+	590 ± 30	calculated
Po XXIII	22+	670 ± 30	calculated
Po XXIV	23+	700 ± 30	calculated
Po XXV	24+	740 ± 40	calculated
Po XXVI	25+	800 ± 40	calculated
Po XXVII	26+	870 ± 40	calculated
Po XXVIII	27+	930 ± 50	calculated
Po XXIX	28+	990 ± 50	calculated
Po XXX	29+	1060 ± 50	calculated
Po XXXI	30+	1120 ± 60	calculated
Po XXXII	31+	1180 ± 60	calculated
Po XXXIII	32+	1250 ± 60	calculated
Po XXXIV	33+	1320 ± 70	calculated
Po XXXV	34+	1380 ± 70	calculated
Po XXXVI	35+	1440 ± 70	calculated
Po XXXVII	36+	1510 ± 70	calculated
Po XXXVIII	37+	1570 ± 70	calculated
Po XXXIX	38+	1865 ± 4	calculated
Po XL	39+	1923 ± 4	calculated
Po XLI	40+	1986 ± 4	calculated
Po XLII	41+	2052 ± 4	calculated
Po XLIII	42+	2115 ± 4	calculated
Po XLIV	43+	2177 ± 4	calculated
Po XLV	44+	2281 ± 4	calculated
Po XLVI	45+	2345 ± 4	calculated
Po XLVII	46+	2414 ± 4	calculated
Po XLVIII	47+	2480 ± 4	calculated
Po XLIX	48+	2740 ± 4	calculated
Po L	49+	2803 ± 4	calculated
Po LI	50+	2873 ± 4	calculated
Po LII	51+	2938 ± 4	calculated
Po LIII	52+	3194 ± 4	calculated
Po LIV	53+	3268 ± 5	calculated
Po LV	54+	3450 ± 5	calculated
Po LVI	55+	3524.2 ± 2.5	semi-empirical
Po LVII	56+	5785 ± 5	calculated
Po LVIII	57+	5930 ± 6	calculated
Po LIX	58+	6084 ± 6	calculated
Po LX	59+	6248 ± 7	calculated
Po LXI	60+	6405 ± 10	calculated
Po LXII	61+	6557 ± 12	calculated
Po LXIII	62+	6856 ± 15	calculated
Po LXIV	63+	7015 ± 19	calculated
Po LXV	64+	7191 ± 24	calculated
Po LXVI	65+	7350 ± 30	calculated
Po LXVII	66+	7810 ± 40	calculated
Po LXVIII	67+	7950 ± 40	calculated
Po LXIX	68+	8100 ± 50	calculated
Po LXX	69+	8240 ± 50	calculated
Po LXXI	70+	9050 ± 60	calculated
Po LXXII	71+	9220 ± 60	calculated
Po LXXIII	72+	9550 ± 70	calculated
Po LXXIV	73+	9710 ± 90	calculated
Po LXXV	74+	20670 ± 90	calculated
Po LXXVI	75+	21050 ± 100	calculated
Po LXXVII	76+	21470 ± 110	calculated
Po LXXVIII	77+	21860 ± 120	calculated
Po LXXIX	78+	24860 ± 120	calculated
Po LXXX	79+	25360 ± 140	calculated
Po LXXXI	80+	25990 ± 150	calculated
Po LXXXII	81+	26390.4 ± 0.4	calculated
Po LXXXIII	82+	105064.3 ± 0.4	calculated
Po LXXXIV	83+	106983.4 ± 0.5	calculated

Value type as given by NIST ASD: measured - from evaluated experimental data; calculated - from ab initio calculations (mostly highly ionised atoms that have not been measured; for the simplest ones, e.g. H I, the calculation is more accurate than measurement); semi-empirical - from interpolation, extrapolation or another semi-empirical method.

Photos

Photo of the element: Polonium (Po) — © images-of-elements.com (CC BY 3.0)

Isotopes (42)

A	N	Half-life	Decay
Po-186	102	28 μs	α
Po-187	103	1.4 ms	α
Po-188	104	270 μs	α
Po-189	105	3.5 ms	α
Po-190	106	2.45 ms	α
Po-191	107	22 ms	α
Po-192	108	32.2 ms	α
Po-193	109	410 ms	α
Po-194	110	392 ms	α
Po-195	111	4.64 s	α
Po-196	112	5.63 s	α
Po-197	113	54 s	α
Po-198	114	1.76 min	α
Po-199	115	5.5 min	EC/β⁺
Po-200	116	11.5 min	EC/β⁺
Po-201	117	15.5 min	EC/β⁺
Po-202	118	44.6 min	EC/β⁺
Po-203	119	36.7 min	EC/β⁺
Po-204	120	3.518 h	EC/β⁺
Po-205	121	1.79 h	EC/β⁺
Po-206	122	8.8 d	EC/β⁺
Po-207	123	5.80 h	EC/β⁺
Po-208	124	2.898 a	α
Po-209	125	124 a	α
Po-210	126	138.378 d	α
Po-211	127	0.516 s	α
Po-212	128	295.0 ns	α
Po-213	129	3.706 μs	α
Po-214	130	163.48 μs	α
Po-215	131	1.781 ms	α
Po-216	132	144.0 ms	α
Po-217	133	1.53 s	α
Po-218	134	3.097 min	α
Po-219	135	10.3 min	β⁻
Po-220	136	unknown	β⁻
Po-221	137	1.9 min	β⁻
Po-222	138	2 min	β⁻
Po-223	139	unknown	β⁻
Po-224	140	unknown	β⁻
Po-225	141	unknown	β⁻
Po-226	142	unknown	β⁻
Po-227	143	unknown	β⁻

Data sources

PubChem Periodic Table API - Retrieved on 29 June 2026 - licence: CC0
IUPAC CIAAW - Abridged Standard Atomic Weights 2024 - Table version: 2024 - licence: Public domain
NNDC Wallet Cards 2023 - Data as of 15 October 2024 - licence: Public domain
Images of Elements - Retrieved on 29 June 2026 - licence: CC BY 3.0

More about the data sources