Fm

Fermium

Z 100 257.0 g/molActinide Radioactive

Overview Atomic Properties Thermodynamics Electromagnetism Isotopes


²⁴¹Fm	141	241.0743	69,220.0	---	730.0 µs	(5/2+)	α²³⁷Cf(<14%) β⁺²⁴¹Es(<12%) SF	2008
²⁴²Fm	142	242.0734	68,400.0	---	800.0 µs	0+	SF(100%) α²³⁸Cf	1975
²⁴³Fm	143	243.0744	69,320.0	---	231.0 ms	(7/2-)	α²³⁹Cf(91%) SF(9%) β⁺²⁴³Es	1981
²⁴⁴Fm	144	244.074	68,960.0	---	3.12 ms	0+	SF(>97%) β⁺²⁴⁴Es(<2%) α²⁴⁰Cf(<1%)	1967
²⁴⁵Fm	145	245.0754	70,190.0	---	4.2 s	(1/2+)	α²⁴¹Cf(100%) β⁺²⁴⁵Es(<7%) SF(<0.3%)	1967
²⁴⁶Fm	146	246.0754	70,191.0	---	1.54 s	0+	α²⁴²Cf(93.2%) SF(6.8%) EC²⁴⁶Es(<1.3%)	1966
²⁴⁷Fm	147	247.0769	71,670.0	---	31.0 s	(7/2+)	α²⁴³Cf(64%) β⁺²⁴⁷Es	1967
^247mFm	147	247.077	71,720.0	---	5.1 s	(1/2+)	α²⁴³Cf(88%) β⁺²⁴⁷Es γ²⁴⁷Fm	1967
²⁴⁸Fm	148	248.0772	71,898.0	---	34.5 s	0+	α²⁴⁴Cf(~100%) SF(0.1%) β⁺²⁴⁸Es	1958
^248mFm	148	248.0785	73,100.0	---	10.1 ms	(6+)	γ²⁴⁸Fm α²⁴⁴Cf β⁺²⁴⁸Es	2010
²⁴⁹Fm	149	249.0789	73,519.0	---	1.6 m	7/2+	α²⁴⁵Cf(33%) β⁺²⁴⁹Es	1960
²⁵⁰Fm	150	250.0795	74,072.0	---	31.0 m	0+	α²⁴⁶Cf(~100%) SF(0.007%) EC²⁵⁰Es	1954
^250mFm	150	250.0808	75,271.0	---	1.92 s	(8-)	γ²⁵⁰Fm(100%) α²⁴⁶Cf β⁺²⁵⁰Es SF	1973
²⁵¹Fm	151	251.0815	75,959.0	---	5.3 h	9/2-	β⁺²⁵¹Es(98.2%) α²⁴⁷Cf(1.8%)	1957
^251mFm	151	251.0818	76,159.0	---	21.8 µs	5/2+	γ²⁵¹Fm(100%)	1970
²⁵²Fm	152	252.0825	76,817.0	---	1.06 d	0+	α²⁴⁸Cf(~100%) SF(0.002%) β⁺	1956
²⁵³Fm	153	253.0852	79,345.5	---	3.0 d	1/2+	EC²⁵³Es(88%) α²⁴⁹Cf(12%)	1957
^253mFm	153	253.0853	79,486.0	---	---	(7/2+)	γ²⁵³Fm	---
²⁵³ⁿFm	153	253.0856	79,697.0	---	560.0 ns	(11/2-)	γ²⁵³Fm(100%)	2011
²⁵⁴Fm	154	254.0869	80,902.5	---	3.24 h	0+	α²⁵⁰Cf(99.941%) SF(0.059%)	1954
²⁵⁵Fm	155	255.09	83,800.0	---	20.07 h	7/2+	α²⁵¹Cf(~100%) SF(2.4e-5%)	1954
²⁵⁶Fm	156	256.0918	85,485.0	---	2.62 h	0+	SF(91.9%) α²⁵²Cf(8.1%)	1955
²⁵⁷Fm	157	257.0951	88,590.0	---	100.5 d	9/2+	α²⁵³Cf(99.79%) SF(0.21%)	1964
²⁵⁸Fm	158	258.0971	90,430.0	---	370.0 µs	0+	SF(100%) α²⁵⁴Cf	1971
²⁵⁹Fm	159	259.1006	93,700.0	---	1.5 s	---	SF(100%)	1980
²⁶⁰Fm	160	260.1028	95,770.0	---	1.0 m	0+	SF	---