Periodic TableAll elementsAmericium
No. 095
Am
243 u
Element · Actinide

Americium

Americium (镅, symbol Am) is chemical element number 95, an Actinide in period 7 of the periodic table, with a standard atomic weight of about 243. Synthetic radioactive metal. Commonly used in smoke detectors.

Period 7Group —[Rn] 5f⁷ 7s²

Properties

Atomic number95
SymbolAm
Atomic mass243 u
CategoryActinide
Period7
Group
Electron configuration[Rn] 5f⁷ 7s²
Electronegativity1.13
Covalent radius180 pm
Density13.69 g/cm³
Melting point1449 K
Boiling point2880 K
DiscoverySeaborg, James, Morgan, Ghiorso, 1944

Overview

Synthetic radioactive metal. Commonly used in smoke detectors. Americium (Am) holds position 95 in the periodic table, an Actinide in period 7. As an actinide it is typically radioactive and closely tied to nuclear technology.

Its electron configuration is [Rn] 5f⁷ 7s², with 2 electrons in the outer shell, and an electronegativity of about 1.13 (Pauling). Around 25 °C it is usually a solid; it melts near 1449 K (1175.9 °C), boils near 2880 K (2606.9 °C), has a density around 13.69 g/cm³.

In industry and daily life it turns up in Research and Nuclear. On the safety side, it carries a high hazard rating. It was first described by Seaborg, James, Morgan, Ghiorso in 1944. Browse elements of the same category in the browse view.

Electron shells

Am95

Electrons per shell: 2 · 8 · 18 · 32 · 25 · 8 · 2

Main uses

Hazard

HighRadioactive

Compounds containing Americium

No compounds in this knowledge base contain Americium yet.

Data sources

Atomic mass uses IUPAC (CIAAW) standard atomic weights; the covalent radius is from Cordero et al. (2008). Verify on the RSC Periodic Table, PubChem and Wikipedia. Educational reference only.