Curium (Cm)

Isotopes of Curium 

Isotope Atomic Mass Half-life Mode of Decay Nuclear Spin Nuclear Magnetic Moment
Cm-240 240.05552 27 hours α to Pu-236; 
EC to Am-240;
0 No data available 
Cm-241 241.05765 32.80 days α to Pu-237;
EC to Am-241
1/2 No data available 
Cm-242 242.05883 162.80 days α to Pu-238;
0 No data available 
Cm-243 243.06138 28.50 years α to Pu-239;
EC to Am-243
5/2 0.41
Cm-244 244.06275 18.11 years α to Pu-240;
0 No data available 
Cm-245 245.06548 8500 years α to Pu-241;
7/2 No data available 
Cm-246 246.06722 4780 years α to Pu-242;
0 No data available 
Cm-247 247.070347 1.56 x 107 years α to Pu-243 9/2 0.37
Cm-248 248.07234 3.40 x 105 years α to Pu-244;
0 No data available 
Cm-249 249.07595 64.15 minutes ß- to Bk-249 1/2 No data available 
Cm-250 250.07835 9700 years α to Pu-246;
ß- to Bk-250;
0 No data available 


Curium is a radioactive rare earth metal. It was first produced in 1944 in a cyclotron at the University of California, Berkeley, USA, by Glenn T. Seaborg, Ralph A. James and Albert Ghiorso, who bombarded Plutonium-239 with α-particles. It takes its name from that of Pierre and Marie Curie, who were known for their research on radioactivity.

Curium is a hard, brittle, radioactive silvery metal. It is paramagnetic in ambient conditions and becomes antiferromagnetic when it cools. It oxidizes readily. It forms strongly fluorescent complexes with various organic compounds. It does not occur in nature and must be made in a nuclear reactor by neutron capture reactions from plutonium and americium isotopes. It tarnishes slowly in dry air at room temperature. The most stable isotope is Curium-247, which has a half-life of almost 16 million years.

All known isotopes of curium are radioactive. When introduced into the human body, curium accumulates in the bones, lungs and liver, promoting cancer.  

Properties of Curium

Name Curium
Symbol Cm
Atomic number 96
Atomic weight [247]
Standard state Solid at 298 °K
CAS Registry ID 7440-51-9
Group in periodic table N/A 
Group name Actinoid
Period in periodic table 7 (Actinoid)
Block in periodic table f-block
Color Silver
Classification Metallic
Melting point 1613 °K [or 1340 °C or 2444 °F]
Boiling point 3383 °K [or 3110 °C or 5630 °F]
Density of solid 13.51 g/cm3
Electron configuration [Rn]5f76d17s2

Isotope Supplier: ISOFLEX logo