Americium: the essentials
- Name: americium
- Symbol: Am
- Atomic number: 95
- Relative atomic mass (Ar): [ 243 ] (longest lived isotope)
- Standard state: solid at 298 K
- Appearance: silvery white
- Classification: Metallic
- Group in periodic table:
- Group name: Actinoid
- Period in periodic table: 7 (actinoid)
- Block in periodic table: f
- Shell structure: 126.96.36.199.25.8.2
- CAS Registry: 7440-35-9
Americium atoms have 95 electrons and the shell structure is 188.8.131.52.25.8.2. The ground state electronic configuration of neutral americium is [Rn].5f7.7s2 and the term symbol of americium is 8S7/2.
The lustre of freshly prepared americium metal is whiter and more silvery than plutonium or neptunium prepared in the same manner. Americium is a component of the smoke detector above.
Americium appears to be more malleable than uranium or neptunium and americium tarnishes slowly in dry air at room temperature. Americium is a radioactive rare earth metal which must be handled with care to avoid contact, since it is a heavy α and γ emitter. It is named after America. The α activity of 241Am is about three times that of radium. Americium is available to qualified users in the UK and in the USA.
Americium is a key component of some smoke detectors.
Americium: physical properties
- Density of solid: 13780 kg m-3
- Molar volume: 17.63 cm3
- Thermal conductivity: 10 (estimate) W m‑1 K‑1
Americium: heat properties
- Melting point: 1449 [1176 °C (2149 °F)] K
- Boiling point: 2880 [2607 °C (4725 °F)] K
- Enthalpy of fusion: 20.5 kJ mol-1
Americium: atom sizes
- Atomic radius (empirical): 175 pm
- Molecular single bond covalent radius: 166 (coordination number 3) ppm
- van der Waals radius: (no data) ppm
- Pauling electronegativity: 1.3 (Pauling units)
- Allred Rochow electronegativity: 1.2 (Pauling units)
- Mulliken-Jaffe electronegativity: (no data)
Americium: orbital properties
- First ionisation energy: 576.38 kJ mol‑1
- Second ionisation energy: 1130 kJ mol‑1
- Third ionisation energy: 2090 kJ mol‑1
- Universe: (no data) ppb by weight
- Crustal rocks: (no data) ppb by weight
- Human: (no data) ppb by weight
Americium: crystal structure
Americium: biological data
- Human abundance by weight: (no data) ppb by weight
Americium has no biological role.
Reactions of americium as the element with air, water, halogens, acids, and bases where known.
Americium: binary compounds
Binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and other compounds of americium where known.
Americium: compound properties
Bond strengths; lattice energies of americium halides, hydrides, oxides (where known); and reduction potentials where known.
Americium: historyAmericium was discovered by Glenn Seaborg, Ralph James., L. Morgan, Albert Ghiorso in 1944 at USA. Origin of name: from the English word "America".
Isolation: coming soon!