Is einsteinium a metal?

Yes. Einsteinium is a metal, classified as an actinide on the periodic table.

How many protons does einsteinium have?

Einsteinium has 99 protons. Its atomic number is 99, which is also the number of electrons in a neutral atom of einsteinium.

What group and period is einsteinium in?

Einsteinium is in period 7 of the periodic table. As an actinide in the f-block, it sits in a separate row below the main table and has no standard group number.

What is the atomic mass of einsteinium?

The atomic mass of einsteinium is 252 u (unified atomic mass units).

Element 99

Einsteinium (Es)

Actinide · Period 7 · f-block

Einsteinium (Es) is element 99 of the periodic table, an actinide in period 7 (f-block) with an atomic mass of 252 and is a solid at standard conditions.

At a glance

Atomic number: 99
Symbol: Es
Atomic mass: 252 u
Category: Actinides
Period: 7
Block: f-block
Phase at STP: solid

Electron structure

Electron configuration: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f11 7s2
Shorthand configuration: [Rn] 5f11 7s2
Electrons per shell: 2, 8, 18, 32, 29, 8, 2
Oxidation states: +2, +3, +4

Physical properties

Melting point: 1,133 K (859.85 °C)
Boiling point: 1,269 K (995.85 °C)
Density: 8.84 g/cm³
Phase: solid

Atomic properties

Electronegativity (Pauling): 1.3
Atomic radius: 186 pm
First ionization energy: 619 kJ/mol
Electron affinity: -29 kJ/mol

Notable isotopes

Notable isotopes of Einsteinium: mass number, atomic mass, natural abundance, and stability.
Isotope	Mass	Abundance	Stability
Es-252	252.08298	-	Half-life 471.7 days

Common uses

Scientific research only

Discovery

Year: 1952
Discovered by: Albert Ghiorso
Country: USA

Frequently asked questions

Is einsteinium a metal?: Yes. Einsteinium is a metal, classified as an actinide on the periodic table.
How many protons does einsteinium have?: Einsteinium has 99 protons. Its atomic number is 99, which is also the number of electrons in a neutral atom of einsteinium.
What group and period is einsteinium in?: Einsteinium is in period 7 of the periodic table. As an actinide in the f-block, it sits in a separate row below the main table and has no standard group number.
What is the atomic mass of einsteinium?: The atomic mass of einsteinium is 252 u (unified atomic mass units).

Keep exploring

Einsteinium's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.