Element: Uranium

General data

Element name	Uranium
Chemical symbol	U
Atomic number Z	92
Year discovered	1789
Standard state (25°C)	Solid
Category	Actinide
Block	f
Atomic mass	238.03
CPK color	#008FFF

Physical properties

Melting point	1408 K (1135 °C)
Boiling point	4404 K (4131 °C)
Density	18.95 g/cm³

Energy properties

First ionization energy	6.194 eV
Electron affinity	no data

Atomic structure

Protons	92 (Atomic number)
Neutrons (U-238, most abundant isotope)	146
Electrons	92
Electron configuration	[Rn] 7s² 5f³ 6d¹
Oxidation states	+6, +5, +4, +3
Electronegativity (Pauling)	1.38
Atomic radius (van der Waals)	240 pm

Ionization energies - NIST ASD (92 states)

State	Charge	Ioniz. energy (eV)	Type
U I	0+	6.19405 ± 0.00006	measured
U II	1+	11.6 ± 0.4	measured
U III	2+	19.8 ± 0.3	measured
U IV	3+	36.7 ± 1	measured
U V	4+	46 ± 1.9	calculated
U VI	5+	62 ± 1.6	semi-empirical
U VII	6+	89 ± 2	calculated
U VIII	7+	101 ± 2.1	calculated
U IX	8+	116 ± 2.2	calculated
U X	9+	128.9 ± 2.2	calculated
U XI	10+	158 ± 2.4	calculated
U XII	11+	173 ± 2.5	calculated
U XIII	12+	210 ± 3	calculated
U XIV	13+	227 ± 3	calculated
U XV	14+	323 ± 3	calculated
U XVI	15+	348 ± 3	calculated
U XVII	16+	375 ± 3	calculated
U XVIII	17+	402 ± 3	calculated
U XIX	18+	431 ± 3	calculated
U XX	19+	458 ± 4	calculated
U XXI	20+	497 ± 4	calculated
U XXII	21+	525 ± 4	calculated
U XXIII	22+	557 ± 4	calculated
U XXIV	23+	585 ± 4	calculated
U XXV	24+	730 ± 40	calculated
U XXVI	25+	770 ± 40	calculated
U XXVII	26+	800 ± 40	calculated
U XXVIII	27+	840 ± 40	calculated
U XXIX	28+	930 ± 50	calculated
U XXX	29+	970 ± 50	calculated
U XXXI	30+	1070 ± 50	calculated
U XXXII	31+	1110 ± 60	calculated
U XXXIII	32+	1210 ± 60	calculated
U XXXIV	33+	1290 ± 60	calculated
U XXXV	34+	1370 ± 70	calculated
U XXXVI	35+	1440 ± 70	calculated
U XXXVII	36+	1520 ± 80	calculated
U XXXVIII	37+	1590 ± 80	calculated
U XXXIX	38+	1670 ± 80	calculated
U XL	39+	1750 ± 90	calculated
U XLI	40+	1830 ± 90	calculated
U XLII	41+	1910 ± 100	calculated
U XLIII	42+	1990 ± 100	calculated
U XLIV	43+	2070 ± 100	calculated
U XLV	44+	2140 ± 110	calculated
U XLVI	45+	2220 ± 110	calculated
U XLVII	46+	2578 ± 4	calculated
U XLVIII	47+	2646 ± 4	calculated
U XLIX	48+	2718 ± 4	calculated
U L	49+	2794 ± 4	calculated
U LI	50+	2867 ± 4	calculated
U LII	51+	2938 ± 4	calculated
U LIII	52+	3073 ± 4	calculated
U LIV	53+	3147 ± 5	calculated
U LV	54+	3228 ± 5	calculated
U LVI	55+	3301 ± 5	calculated
U LVII	56+	3602 ± 5	calculated
U LVIII	57+	3675 ± 6	calculated
U LIX	58+	3753 ± 6	calculated
U LX	59+	3827 ± 7	calculated
U LXI	60+	4214 ± 10	calculated
U LXII	61+	4299 ± 12	calculated
U LXIII	62+	4513 ± 15	calculated
U LXIV	63+	4598 ± 5	semi-empirical
U LXV	64+	7393 ± 24	calculated
U LXVI	65+	7550 ± 30	calculated
U LXVII	66+	7730 ± 40	calculated
U LXVIII	67+	7910 ± 40	calculated
U LXIX	68+	8090 ± 50	calculated
U LXX	69+	8260 ± 50	calculated
U LXXI	70+	8650 ± 60	calculated
U LXXII	71+	8830 ± 60	calculated
U LXXIII	72+	9030 ± 70	calculated
U LXXIV	73+	9210 ± 90	calculated
U LXXV	74+	9720 ± 90	calculated
U LXXVI	75+	9870 ± 100	calculated
U LXXVII	76+	10040 ± 110	calculated
U LXXVIII	77+	10200 ± 120	calculated
U LXXIX	78+	11410 ± 120	calculated
U LXXX	79+	11600 ± 140	calculated
U LXXXI	80+	11990 ± 150	calculated
U LXXXII	81+	12160 ± 160	calculated
U LXXXIII	82+	25260 ± 170	calculated
U LXXXIV	83+	25680 ± 190	calculated
U LXXXV	84+	26150 ± 200	calculated
U LXXXVI	85+	26590 ± 220	calculated
U LXXXVII	86+	31060 ± 240	calculated
U LXXXVIII	87+	31640 ± 250	calculated
U LXXXIX	88+	32400 ± 300	calculated
U XC	89+	32836.5 ± 0.6	calculated
U XCI	90+	129569.9 ± 0.7	calculated
U XCII	91+	131816.2 ± 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: Uranium (U) — © images-of-elements.com (CC BY 3.0)

Isotopes (28)

A	N	Half-life	Decay
U-214	122	0.5 ms	α
U-215	123	0.7 ms	α
U-216	124	5 ms	α
U-217	125	16 ms	α
U-218	126	0.63 ms	α
U-219	127	60 μs	α
U-221	129	0.66 μs	α
U-222	130	4.7 μs	α
U-223	131	62 μs	α
U-224	132	396 μs	α
U-225	133	61 ms	α
U-226	134	267 ms	α
U-227	135	1.1 min	α
U-228	136	9.1 min	α
U-229	137	57.8 min	α
U-230	138	20.23 d	α
U-231	139	4.2 d	EC
U-232	140	68.9 a	α
U-233	141	1.5919×10⁵ a	α
U-234	142	2.455×10⁵ a	α
U-235	143	7.040×10⁸ a	α
U-236	144	2.343×10⁷ a	α
U-237	145	6.752 d	β⁻
U-238	146	4.463×10⁹ a	α
U-239	147	23.45 min	β⁻
U-240	148	14.1 h	β⁻
U-241	149	unknown	β⁻
U-242	150	16.8 min	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