Es
Einsteinium
Element 99 · Actinide
Einsteinium (Es)
Einsteinium is a radioactive metal first found in the debris of the first hydrogen bomb test.
- Actinide
- Period 7
- f-block series
- f-block
- solid at room temperature
- ☢ Radioactive
Key properties
- Atomic mass
- [252]
- u
- Electron configuration
- [Rn] 5f11 7s2
- Melting point
- 859.9 °C
- 1,133 K
- Boiling point
- 995.9 °C
- 1,269 K
- Density
- 8.84 g/cm³
- Electronegativity
- 1.3
- Pauling
- Atomic radius
- 245 pm
- van der Waals
- 1st ionisation energy
- 6.42 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 einsteinium
- 01
It was discovered in fallout from the 1952 “Ivy Mike” test on Enewetak Atoll.
- 02
Its discovery was classified until 1955.
- 03
Einsteinium glows blue from its own intense radioactivity.
Applications
What is einsteinium used for?
- Research
History
Discovery & name origin
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 99
- Atomic mass
- [252] u
- Group
- Actinides (3)
- Period
- 7
- Block
- f-block
- Electron configuration
- [Rn] 5f11 7s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f11
- Electrons per shell
- 2, 8, 18, 32, 29, 8, 2
- Electronegativity (Pauling)
- 1.3
- Electron affinity
- —
- Atomic radius (van der Waals)
- 245 pm
- Stable isotopes
- None — all isotopes are radioactive
Oxidation states
Highlighted: common oxidation states (+3).
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 1,133 K · 859.9 °C · 1,579.7 °F
- Boiling point
- 1,269 K · 995.9 °C · 1,824.5 °F
- Density
- 8.84 g/cm³
- Molar heat capacity
- —
- Appearance
- Silver-coloured
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Einsteinium questions
What is Es on the periodic table?
Es is the symbol for einsteinium, element 99 on the periodic table. It sits in period 7, in the f-block, in the actinide category, and has an atomic mass of [252].
What is the atomic number of einsteinium?
Einsteinium has atomic number 99, so every einsteinium atom has 99 protons in its nucleus. Its symbol is Es and its atomic mass is [252].
Who discovered einsteinium?
Einsteinium was discovered by Albert Ghiorso in 1952 (United States). The name comes from from Albert Einstein.
What is einsteinium used for?
Einsteinium is used for: research.
Is einsteinium a metal?
Yes. Einsteinium is a actinide, one of the metallic elements.
What is the electron configuration of einsteinium?
The electron configuration of einsteinium is [Rn] 5f11 7s2. Its 99 electrons are arranged in shells as 2, 8, 18, 32, 29, 8, 2.