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Americium Facts

Chemical & Physical Properties of Americium

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This is a disk of americium-241 viewed under a microscope.

This is a disk of americium-241 viewed under a microscope.

Bionerd, Creative Commons License Americium is a lustrous silvery-white metal that slowly tarnishes in air.

Americium is a lustrous silvery-white metal that slowly tarnishes in air. The triangle in the glass tube is the world's first sample of americium, produced in a 60-inch cyclotron in 1944.

Lawrence Berkeley National Lab This diagram of an americium atom shows the electron shell.

This diagram of an americium atom shows the electron shell.

Greg Robson,Creative Commonns License
Periodic Table of the Elements

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.)

 

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