99
Es
252
Einsteinium (Es)
Element 99 · Period 7 · Actinide series
actinide
solid at room temp
f-block
radioactive
synthetic
About Einsteinium
Named after Einstein. Discovered in first thermonuclear bomb test debris.
Physical Properties
Atomic Mass
252 u
State at 25°C
Solid
Melting Point
860 °C
Density
8.84 g/cm³
Magnetism
Paramagnetic
Atomic Properties
Electron Configuration
[Rn] 5f¹¹ 7s²
Electron Shells
2, 8, 18, 32, 29, 8, 2
Electronegativity
1.3
Atomic Radius
245 pm
Ionization Energy
619 kJ/mol
Oxidation States
+3
Discovery & History
Discovered By
Albert Ghiorso
Discovery Year
1952
Named By
Albert Ghiorso
Name origin: Albert Einstein
Frequently Asked Questions
- Is Einsteinium a metal, nonmetal, or metalloid?
- Einsteinium is classified as a actinide.
- What state is Einsteinium in at room temperature?
- Einsteinium is a solid at standard room temperature (25°C).
- What is the atomic mass of Einsteinium?
- Einsteinium has an atomic mass of 252 atomic mass units (u).
- Who discovered Einsteinium?
- Einsteinium was discovered by Albert Ghiorso in 1952.
- Where is Einsteinium on the periodic table?
- Einsteinium is element number 99, located in period 7, part of the actinide series shown below the main table.