Element: Nobelium

This element has only been produced a few atoms at a time, so most of its properties have never been measured - missing values are omitted.

General data

Element name	Nobelium
Chemical symbol	No
Atomic number Z	102
Year discovered	1957
Standard state (25°C)	Solid
Category	Actinide
Block	f
Atomic mass	[259]
CPK color	#BD0D87

Physical properties

Melting point	1100 K (827 °C)

Energy properties

First ionization energy	6.65 eV

Atomic structure

Protons	102 (Atomic number)
Neutrons (No-259, longest-lived isotope)	157
Electrons	102
Electron configuration	[Rn] 7s² 5f¹⁴
Oxidation states	+3, +2
Electronegativity (Pauling)	1.3

Ionization energies - NIST ASD (102 states)

State	Charge	Ioniz. energy (eV)	Type
No I	0+	6.62621 ± 0.00005	measured
No II	1+	12.93 ± 0.04	calculated
No III	2+	25.8 ± 0.4	semi-empirical
No IV	3+	41.5 ± 0.4	semi-empirical
No V	4+	60 ± 1.9	calculated
No VI	5+	74 ± 2	calculated
No VII	6+	97 ± 2	calculated
No VIII	7+	119 ± 2.1	calculated
No IX	8+	140 ± 2.2	calculated
No X	9+	170 ± 2.2	calculated
No XI	10+	187 ± 2.4	calculated
No XII	11+	216 ± 2.5	calculated
No XIII	12+	246 ± 12	calculated
No XIV	13+	267 ± 14	calculated
No XV	14+	285 ± 12	calculated
No XVI	15+	312 ± 16	calculated
No XVII	16+	341 ± 17	calculated
No XVIII	17+	367 ± 19	calculated
No XIX	18+	394 ± 20	calculated
No XX	19+	422 ± 21	calculated
No XXI	20+	448 ± 22	calculated
No XXII	21+	475 ± 24	calculated
No XXIII	22+	496 ± 4	calculated
No XXIV	23+	520 ± 4	calculated
No XXV	24+	701 ± 4	calculated
No XXVI	25+	734 ± 4	calculated
No XXVII	26+	768 ± 4	calculated
No XXVIII	27+	805 ± 4	calculated
No XXIX	28+	840 ± 4	calculated
No XXX	29+	875 ± 4	calculated
No XXXI	30+	934 ± 4	calculated
No XXXII	31+	969 ± 4	calculated
No XXXIII	32+	1010 ± 4	calculated
No XXXIV	33+	1045 ± 5	calculated
No XXXV	34+	1220 ± 60	calculated
No XXXVI	35+	1260 ± 60	calculated
No XXXVII	36+	1300 ± 70	calculated
No XXXVIII	37+	1350 ± 70	calculated
No XXXIX	38+	1500 ± 70	calculated
No XL	39+	1550 ± 80	calculated
No XLI	40+	1680 ± 80	calculated
No XLII	41+	1730 ± 90	calculated
No XLIII	42+	1920 ± 100	calculated
No XLIV	43+	2010 ± 100	calculated
No XLV	44+	2110 ± 110	calculated
No XLVI	45+	2200 ± 110	calculated
No XLVII	46+	2290 ± 110	calculated
No XLVIII	47+	2380 ± 120	calculated
No XLIX	48+	2470 ± 120	calculated
No L	49+	2570 ± 120	calculated
No LI	50+	2680 ± 140	calculated
No LII	51+	2760 ± 140	calculated
No LIII	52+	2860 ± 150	calculated
No LIV	53+	2950 ± 150	calculated
No LV	54+	3050 ± 150	calculated
No LVI	55+	3140 ± 160	calculated
No LVII	56+	3627 ± 5	calculated
No LVIII	57+	3705 ± 6	calculated
No LIX	58+	3790 ± 6	calculated
No LX	59+	3878 ± 7	calculated
No LXI	60+	3962 ± 10	calculated
No LXII	61+	4045 ± 12	calculated
No LXIII	62+	4234 ± 15	calculated
No LXIV	63+	4320 ± 19	calculated
No LXV	64+	4413 ± 24	calculated
No LXVI	65+	4500 ± 30	calculated
No LXVII	66+	4850 ± 40	calculated
No LXVIII	67+	4930 ± 40	calculated
No LXIX	68+	5030 ± 50	calculated
No LXX	69+	5110 ± 50	calculated
No LXXI	70+	5750 ± 60	calculated
No LXXII	71+	5850 ± 60	calculated
No LXXIII	72+	6110 ± 70	calculated
No LXXIV	73+	6210 ± 90	calculated
No LXXV	74+	9680 ± 90	calculated
No LXXVI	75+	9860 ± 100	calculated
No LXXVII	76+	10060 ± 110	calculated
No LXXVIII	77+	10270 ± 120	calculated
No LXXIX	78+	10470 ± 120	calculated
No LXXX	79+	10660 ± 140	calculated
No LXXXI	80+	11200 ± 150	calculated
No LXXXII	81+	11410 ± 160	calculated
No LXXXIII	82+	11630 ± 170	calculated
No LXXXIV	83+	11840 ± 190	calculated
No LXXXV	84+	12420 ± 200	calculated
No LXXXVI	85+	12600 ± 220	calculated
No LXXXVII	86+	12800 ± 240	calculated
No LXXXVIII	87+	12980 ± 250	calculated
No LXXXIX	88+	15000 ± 300	calculated
No XC	89+	15200 ± 300	calculated
No XCI	90+	15600 ± 300	calculated
No XCII	91+	15800 ± 300	calculated
No XCIII	92+	31700 ± 400	calculated
No XCIV	93+	32200 ± 400	calculated
No XCV	94+	32700 ± 400	calculated
No XCVI	95+	33200 ± 400	calculated
No XCVII	96+	40500 ± 400	calculated
No XCVIII	97+	41200 ± 400	calculated
No XCIX	98+	42100 ± 500	calculated
No C	99+	42632 ± 6	calculated
No CI	100+	166050 ± 7	calculated
No CII	101+	168804 ± 7	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: Nobelium (No) — © images-of-elements.com (CC BY 3.0)

Isotopes (13)

A	N	Half-life	Decay
No-249	147	38 ms	α
No-250	148	4.6 μs	SF
No-251	149	0.80 s	α
No-252	150	2.45 s	α
No-253	151	1.61 min	α
No-254	152	51.2 s	α
No-255	153	3.52 min	EC/β⁺
No-256	154	2.93 s	α
No-257	155	24.5 s	α
No-258	156	1.23 ms	SF
No-259	157	58 min	α
No-260	158	107 ms	SF
No-262	160	≈ 5 ms	SF

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