059Lanthanide · Group 3 · Period 6

Praseodymium

Praseodymium (Pr) is element 59, a lanthanide in the f-block — group 3, period 6. It is a solid at room temperature with 6 electron shells (2, 8, 18, 21, 8, 2) and an atomic mass of 140.907662 u.

Atomic mass: 140.9 u
Phase · STP: solid
Melting: 1208 K · 935 °C
Boiling: 3403 K · 3130 °C
Electronegativity: 1.13
Density: 6.77 g/cm³

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

Identity

Atomic number: 59
Standard atomic weight: 140.9 u
Category: Lanthanide
Group: 3
Period: 6
Block: f-block
Oxidation states: +3

Physical properties

Melting point: 1208 K · 935 °C
Boiling point: 3403 K · 3130 °C
Density: 6.77 g/cm³
Molar heat capacity: 27.2 J/(mol·K)
Atomic radius: 239 pm
Electron affinity: 93 kJ/mol

Atomic structure

59protons

82neutrons

59electrons

2valence e⁻

Noble-gas notation: [Xe] 4f3 6s2
Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f3
Electrons per shell: 2, 8, 18, 21, 8, 2

Periodic trends

Where Praseodymium ranks across all 118 elements.

Electronegativity1.13

Ionization energy527 kJ/mol

Electron affinity93 kJ/mol

Density6.77 g/cm³

Atomic radius239 pm

Ionization energies

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

527

1.0k

2.1k

3.8k

5.6k

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

Discovery

Discovered: 1885
Discovered by: Carl Auer von Welsbach
Named by: —
Appearance: grayish white