Am
Americium
Element 95 · Actinide
Americium (Am)
Americium is a radioactive, silvery metal found in nearly every household smoke detector.
- Actinide
- Period 7
- f-block series
- f-block
- solid at room temperature
- ☢ Radioactive
Key properties
- Atomic mass
- [243]
- u
- Electron configuration
- [Rn] 5f7 7s2
- Melting point
- 1,175.9 °C
- 1,449 K
- Boiling point
- 2,010.9 °C
- 2,284 K
- Density
- 13.69 g/cm³
- Electronegativity
- 1.3
- Pauling
- Atomic radius
- 244 pm
- van der Waals
- 1st ionisation energy
- 5.993 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about americium
- 01
A typical smoke detector contains about 0.3 micrograms of americium-241.
- 02
Seaborg revealed its discovery on a children’s radio quiz show before the official announcement.
- 03
Americium-241 is being studied as a long-lived power source for space missions.
Applications
What is americium used for?
- Smoke detectors
- Industrial gauges
- Neutron sources
History
Discovery & name origin
Discovered by
Glenn T. Seaborg, Ralph A. James, Leon O. Morgan, Albert Ghiorso
Year
Where
United States
Name origin
From the Americas, by analogy with europium.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 95
- Atomic mass
- [243] u
- Group
- Actinides (3)
- Period
- 7
- Block
- f-block
- Electron configuration
- [Rn] 5f7 7s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f7
- Electrons per shell
- 2, 8, 18, 32, 25, 8, 2
- Electronegativity (Pauling)
- 1.3
- Electron affinity
- —
- Atomic radius (van der Waals)
- 244 pm
- Stable isotopes
- None — all isotopes are radioactive
Oxidation states
Highlighted: common oxidation states (+6, +5, +4, +3).
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 1,449 K · 1,175.9 °C · 2,148.5 °F
- Boiling point
- 2,284 K · 2,010.9 °C · 3,651.5 °F
- Density
- 13.69 g/cm³
- Molar heat capacity
- 62.7 J/(mol·K)
- Appearance
- Silvery white
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Americium questions
What is Am on the periodic table?
Am is the symbol for americium, element 95 on the periodic table. It sits in period 7, in the f-block, in the actinide category, and has an atomic mass of [243].
What is the atomic number of americium?
Americium has atomic number 95, so every americium atom has 95 protons in its nucleus. Its symbol is Am and its atomic mass is [243].
Who discovered americium?
Americium was discovered by Glenn T. Seaborg, Ralph A. James, Leon O. Morgan and Albert Ghiorso in 1944 (United States). The name comes from from the Americas, by analogy with europium.
What is americium used for?
Americium is used for: smoke detectors; industrial gauges; neutron sources.
Is americium a metal?
Yes. Americium is a actinide, one of the metallic elements.
What is the electron configuration of americium?
The electron configuration of americium is [Rn] 5f7 7s2. Its 95 electrons are arranged in shells as 2, 8, 18, 32, 25, 8, 2.