067Lanthanide · Group 3 · Period 6

Holmium

Holmium (Ho) is element 67, a lanthanide in the f-block — group 3, period 6. It is a solid at room temperature with 6 electron shells (2, 8, 18, 29, 8, 2) and an atomic mass of 164.930332 u.

Atomic mass: 164.9 u
Phase · STP: solid
Melting: 1734 K · 1461 °C
Boiling: 2873 K · 2600 °C
Electronegativity: 1.23
Density: 8.79 g/cm³

Photograph — Unknown authorUnknown author, CC BY 1.0 <https://creativecommons.org/licenses/by/1.0>, via Wikimedia Commons, source: https://images-of-elements.com/holmium.php

Identity

Atomic number: 67
Standard atomic weight: 164.9 u
Category: Lanthanide
Group: 3
Period: 6
Block: f-block
Oxidation states: +3

Physical properties

Melting point: 1734 K · 1461 °C
Boiling point: 2873 K · 2600 °C
Density: 8.79 g/cm³
Molar heat capacity: 27.15 J/(mol·K)
Atomic radius: 216 pm
Electron affinity: 32.61 kJ/mol

Atomic structure

67protons

98neutrons

67electrons

2valence e⁻

Noble-gas notation: [Xe] 4f11 6s2
Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f11
Electrons per shell: 2, 8, 18, 29, 8, 2

Periodic trends

Where Holmium ranks across all 118 elements.

Electronegativity1.23

Ionization energy581 kJ/mol

Electron affinity32.61 kJ/mol

Density8.79 g/cm³

Atomic radius216 pm

Ionization energies

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

581

1.1k

2.2k

4.1k

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

Discovery

Discovered: 1878
Discovered by: Marc Delafontaine
Named by: —
Appearance: silvery white