About

Curium is a hard, dense, silvery radioactive element named in honor of Marie and Pierre Curie. It is a powerful alpha-particle emitter that generates significant heat from decay. This property has allowed it to be used as a power source in radioisotope thermoelectric generators (RTGs) for spacecraft and pacemakers. It was also used to bombard targets to produce heavier elements.

Atomic Properties

Atomic Number96

Atomic Weight247 u

Neutrons (common)151

Electron Configuration[Rn] 5f⁷ 6d¹ 7s²

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 5f⁷ 6d¹ 7s²

Electrons per Shell2, 8, 18, 32, 25, 9, 2

Electronegativity1.3

Oxidation States+3, +4

Covalent Radius169 pm

Ionic Radius97 pm

Periodic Table Position

Group3

Period7

BlockF

Chemical SeriesActinoids

Physical Properties

State at STPsolid

Appearancesilvery-white metallic, glows purple in the dark

Crystal Structurehcp

Magnetic Orderingparamagnetic

Thermal Properties

Melting Point1,613 K

Boiling Point3,383 K

Thermal Conductivity10 W/(m·K)

Specific Heat0.116 J/(g·K)

Heat of Fusion15 kJ/mol

Heat of Vaporization330 kJ/mol

Discovery

Discovered byGlenn T. Seaborg, Ralph A. James, Albert Ghiorso

Discovery Year1,944

Occurrencesynthetic

CAS Number7440-51-9

Electron Configuration

Energy

↿⇂

1s

↿⇂

2s

↿⇂

2p

↿⇂

3s

↿⇂

3p

↿⇂

4s

↿⇂

3d

↿⇂

4p

↿⇂

5s

↿⇂

4d

↿⇂

5p

↿⇂

6s

↿⇂

4f

↿⇂

5d

↿⇂

6p

↿⇂

7s

↿

5f

↿

6d

7p

Isotopes of Curium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
²⁴⁵Cm	245.065490	—	8.25 ky	Alpha Decay
²⁴⁶Cm	246.067220	—	4.706 ky	Alpha Decay, Spontaneous Fission
²⁴⁷Cm	247.070350	—	15.6 My	Alpha Decay
²⁴⁸Cm	248.072340	—	348 ky	Alpha Decay, Spontaneous Fission