068Lanthanide · Group 3 · Period 6

Erbium

Erbium (Er) is element 68, a lanthanide in the f-block — group 3, period 6. It is a solid at room temperature with 6 electron shells (2, 8, 18, 30, 8, 2) and an atomic mass of 167.2593 u.

Atomic mass: 167.3 u
Phase · STP: solid
Melting: 1802 K · 1529 °C
Boiling: 3141 K · 2868 °C
Electronegativity: 1.24
Density: 9.066 g/cm³

Photograph — Jurii, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/erbium.php

Identity

Atomic number: 68
Standard atomic weight: 167.3 u
Category: Lanthanide
Group: 3
Period: 6
Block: f-block
Oxidation states: +3

Physical properties

Melting point: 1802 K · 1529 °C
Boiling point: 3141 K · 2868 °C
Density: 9.066 g/cm³
Molar heat capacity: 28.12 J/(mol·K)
Atomic radius: 235 pm
Electron affinity: 30.1 kJ/mol

Atomic structure

68protons

99neutrons

68electrons

2valence e⁻

Noble-gas notation: [Xe] 4f12 6s2
Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f12
Electrons per shell: 2, 8, 18, 30, 8, 2

Periodic trends

Where Erbium ranks across all 118 elements.

Electronegativity1.24

Ionization energy589.3 kJ/mol

Electron affinity30.1 kJ/mol

Density9.066 g/cm³

Atomic radius235 pm

Ionization energies

Energy to remove each successive electron (kJ/mol).

589.3

1.1k

2.2k

4.1k

Successive ionization energies (kJ/mol, log scale).

Discovery

Discovered: 1843
Discovered by: Carl Gustaf Mosander
Named by: —
Appearance: silvery white