Americium Facts – Element 95 or Am


This is a disk of americium-241 viewed under a microscope. Bionerd, Creative Commons License

This is a disk of americium-241 viewed under a microscope. Bionerd, Creative Commons License

Element Name: Americium

Atomic Number: 95

Symbol: Am

Atomic Weight: 243.0614

Electron Configuration: [Rn] 5f7 7s2

Atomic Number: 95

Element Classification: Radioactive Rare Earth Element (Actinide Series)

Discovered By: G.T.Seaborg, R.A.James, L.O.Morgan, A.Ghiorso

Discovery Date: 1945 (United States)

Name Origin: named for the American continent, similar to the naming of the element europium.

Density (g/cc): 13.67

Melting Point (K): 1267

Boiling Point (K): 2880

Appearance: silvery-white, radioactive metal

Atomic Radius (pm): 173

Atomic Volume (cc/mol): 20.8

Ionic Radius: 92 (+4e) 107 (+3e)

Fusion Heat (kJ/mol): (10.0)

Evaporation Heat (kJ/mol): 238.5

Pauling Negativity Number: 1.3

Oxidation States: 6, 5, 4, 3

References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange’s Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)