95[243]AmAmericium
Americium (Am) — element 95actinide · period 7
Americium is a chemical element with the symbol Am and atomic number 95. It is an actinide in period 7 of the periodic table (the f-block), with a standard atomic mass of [243] u. At room temperature (25 °C) americium is a solid.
💡 Known for: Americium-241 is found in most household smoke detectors.
# Americium properties
| Symbol | Am |
|---|---|
| Atomic number | 95 |
| Atomic mass | [243] u |
| Category | actinide |
| Group | — (f-block, no group number) |
| Period | 7 |
| Block | f-block |
| Electron configuration | [Rn] 5f⁷ 7s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f⁷ 6s² 6p⁶ 7s² |
| Electrons per shell | 2, 8, 18, 32, 25, 8, 2 |
| Protons / electrons | 95 / 95 |
| State at 25 °C | solid |
| Melting point | 1449 K (1175.8 °C, 2148.5 °F) |
| Boiling point | 2880 K (2606.8 °C, 4724.3 °F) |
| Density | 13.69 g/cm³ |
| Electronegativity (Pauling) | 1.13 |
| First ionization energy | 5.974 eV |
| Atomic radius | 175 pm |
| Discovered | 1944 |
# Electron configuration of americium
The electron configuration of americium is [Rn] 5f⁷ 7s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f⁷ 6s² 6p⁶ 7s². Its 95 electrons fill 7 shells as 2, 8, 18, 32, 25, 8, 2, so the outermost shell holds 2 electrons.
# Related elements
PuPlutoniumprevious elementCmCuriumnext elementAcActiniumactinideThThoriumactinidePaProtactiniumactinideUUraniumactinideNpNeptuniumactinideBkBerkeliumactinideCfCaliforniumactinideEsEinsteiniumactinide
# Americium FAQ
What is the atomic number of americium?
The atomic number of americium is 95: every americium atom has 95 protons in its nucleus. Its symbol is Am.
What is the atomic mass of americium?
The standard atomic mass of americium is [243] u (the mass number of its longest-lived isotope, since it has no stable isotopes).
What is the electron configuration of americium?
Americium's electron configuration is [Rn] 5f⁷ 7s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 5f⁷ 6s² 6p⁶ 7s²), with 2, 8, 18, 32, 25, 8, 2 electrons per shell.
Is americium a metal?
Yes. Americium is an actinide, one of the metals.
What is the melting point of americium?
Americium melts at 1449 K (1175.8 °C, 2148.5 °F) and boils at 2880 K (2606.8 °C, 4724.3 °F).
What is americium used for / known for?
Americium-241 is found in most household smoke detectors.