Element: Lawrencium

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	Lawrencium
Chemical symbol	Lr
Atomic number Z	103
Year discovered	1961
Standard state (25°C)	Solid
Category	Actinide
Block	f
Atomic mass	[266]
CPK color	#C70066

Physical properties

Melting point	1900 K (1627 °C)

Energy properties

none - only single atoms have been produced

Atomic structure

Protons	103 (Atomic number)
Neutrons (Lr-266, longest-lived isotope)	163
Electrons	103
Electron configuration	[Rn] 7s² 5f¹⁴ 7p¹ Lawrencium is an exception. The orbital filling rules would give [Rn]7s2 5f14 6d1 (as listed e.g. by PubChem). In such a heavy atom, however, electrons close to the nucleus move at speeds comparable to the speed of light - relativistic effects lower the energy of the 7p orbital below 6d. Relativistic quantum calculations point to [Rn]7s2 5f14 7p1, and the first ionization energy of lawrencium measured in 2015 (Sato et al., Nature 520, 209) agrees with it.
Oxidation states	+3
Electronegativity (Pauling)	1.3

Ionization energies - NIST ASD (103 states)

State	Charge	Ioniz. energy (eV)	Type
Lr I	0+	4.96 ± 0.05	measured
Lr II	1+	14.54 ± 0.04	calculated
Lr III	2+	21.8 ± 0.04	calculated
Lr IV	3+	43.6 ± 0.4	semi-empirical
Lr V	4+	56 ± 1.9	calculated
Lr VI	5+	80 ± 2	calculated
Lr VII	6+	96 ± 2	calculated
Lr VIII	7+	121 ± 2.1	calculated
Lr IX	8+	143 ± 2.2	calculated
Lr X	9+	165 ± 2.2	calculated
Lr XI	10+	197 ± 2.4	calculated
Lr XII	11+	216 ± 2.5	calculated
Lr XIII	12+	244 ± 3	calculated
Lr XIV	13+	269 ± 14	calculated
Lr XV	14+	290 ± 15	calculated
Lr XVI	15+	322 ± 12	calculated
Lr XVII	16+	344 ± 17	calculated
Lr XVIII	17+	374 ± 19	calculated
Lr XIX	18+	403 ± 20	calculated
Lr XX	19+	431 ± 21	calculated
Lr XXI	20+	459 ± 24	calculated
Lr XXII	21+	487 ± 25	calculated
Lr XXIII	22+	510 ± 30	calculated
Lr XXIV	23+	540 ± 30	calculated
Lr XXV	24+	560 ± 30	calculated
Lr XXVI	25+	745 ± 4	calculated
Lr XXVII	26+	779 ± 4	calculated
Lr XXVIII	27+	814 ± 4	calculated
Lr XXIX	28+	852 ± 4	calculated
Lr XXX	29+	888 ± 4	calculated
Lr XXXI	30+	922 ± 4	calculated
Lr XXXII	31+	985 ± 4	calculated
Lr XXXIII	32+	1020 ± 4	calculated
Lr XXXIV	33+	1061 ± 5	calculated
Lr XXXV	34+	1098 ± 5	calculated
Lr XXXVI	35+	1280 ± 60	calculated
Lr XXXVII	36+	1320 ± 70	calculated
Lr XXXVIII	37+	1360 ± 70	calculated
Lr XXXIX	38+	1410 ± 70	calculated
Lr XL	39+	1570 ± 80	calculated
Lr XLI	40+	1620 ± 80	calculated
Lr XLII	41+	1760 ± 90	calculated
Lr XLIII	42+	1810 ± 90	calculated
Lr XLIV	43+	2010 ± 100	calculated
Lr XLV	44+	2100 ± 110	calculated
Lr XLVI	45+	2190 ± 110	calculated
Lr XLVII	46+	2290 ± 110	calculated
Lr XLVIII	47+	2380 ± 120	calculated
Lr XLIX	48+	2470 ± 120	calculated
Lr L	49+	2570 ± 120	calculated
Lr LI	50+	2670 ± 140	calculated
Lr LII	51+	2780 ± 140	calculated
Lr LIII	52+	2860 ± 150	calculated
Lr LIV	53+	2960 ± 150	calculated
Lr LV	54+	3060 ± 150	calculated
Lr LVI	55+	3150 ± 160	calculated
Lr LVII	56+	3250 ± 160	calculated
Lr LVIII	57+	3741 ± 6	calculated
Lr LIX	58+	3821 ± 6	calculated
Lr LX	59+	3906 ± 7	calculated
Lr LXI	60+	3996 ± 10	calculated
Lr LXII	61+	4082 ± 12	calculated
Lr LXIII	62+	4165 ± 15	calculated
Lr LXIV	63+	4360 ± 19	calculated
Lr LXV	64+	4448 ± 24	calculated
Lr LXVI	65+	4540 ± 30	calculated
Lr LXVII	66+	4630 ± 40	calculated
Lr LXVIII	67+	4990 ± 40	calculated
Lr LXIX	68+	5070 ± 50	calculated
Lr LXX	69+	5160 ± 50	calculated
Lr LXXI	70+	5250 ± 60	calculated
Lr LXXII	71+	5920 ± 60	calculated
Lr LXXIII	72+	6030 ± 70	calculated
Lr LXXIV	73+	6290 ± 90	calculated
Lr LXXV	74+	6390 ± 90	calculated
Lr LXXVI	75+	9920 ± 100	calculated
Lr LXXVII	76+	10110 ± 110	calculated
Lr LXXVIII	77+	10310 ± 120	calculated
Lr LXXIX	78+	10520 ± 120	calculated
Lr LXXX	79+	10720 ± 140	calculated
Lr LXXXI	80+	10920 ± 150	calculated
Lr LXXXII	81+	11470 ± 160	calculated
Lr LXXXIII	82+	11680 ± 170	calculated
Lr LXXXIV	83+	11910 ± 190	calculated
Lr LXXXV	84+	12120 ± 200	calculated
Lr LXXXVI	85+	12710 ± 220	calculated
Lr LXXXVII	86+	12890 ± 240	calculated
Lr LXXXVIII	87+	13090 ± 250	calculated
Lr LXXXIX	88+	13300 ± 300	calculated
Lr XC	89+	15300 ± 300	calculated
Lr XCI	90+	15600 ± 300	calculated
Lr XCII	91+	16000 ± 300	calculated
Lr XCIII	92+	16200 ± 400	calculated
Lr XCIV	93+	32400 ± 400	calculated
Lr XCV	94+	32900 ± 400	calculated
Lr XCVI	95+	33400 ± 400	calculated
Lr XCVII	96+	33900 ± 400	calculated
Lr XCVIII	97+	41600 ± 400	calculated
Lr XCIX	98+	42300 ± 500	calculated
Lr C	99+	43200 ± 500	calculated
Lr CI	100+	43759 ± 6	calculated
Lr CII	101+	170116 ± 8	calculated
Lr CIII	102+	172928 ± 9	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: Lawrencium (Lr) — © images-of-elements.com (CC BY 3.0)

Isotopes (14)

A	N	Half-life	Decay
Lr-251	148	24 ms	α
Lr-252	149	0.35 s	α
Lr-253	150	0.65 s	α
Lr-254	151	11.9 s	α
Lr-255	152	31.1 s	α
Lr-256	153	27.9 s	α
Lr-257	154	5.9 s	α
Lr-258	155	3.86 s	α
Lr-259	156	6.2 s	α
Lr-260	157	3.0 min	α
Lr-261	158	42 min	SF
Lr-262	159	≈ 4 h	SF
Lr-264	161	4.9 h	SF
Lr-266	163	11 h	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