Plutonium

Element 94 on the periodic table, symbol Pu, group 3, period 7.

Plutonium is a transuranic radioactive chemical element with symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states.

Appearance: silvery white, tarnishing to dark gray in air

Properties

Atomic Number: 94
Atomic Mass: 244.0000 u
Group: 3
Period: 7
Block: f-block
Category: Actinide
State at 25 °C: Solid
Melting Point: 912.5 K · 639.4 °C
Boiling Point: 3,505 K · 3,231.9 °C
Density: 19.816 g/cm³
Atomic Radius: 175 pm
Electronegativity: 1.28
Oxidation States: +3, +4, +5, +6
Abundance in Crust: Vanishingly rare
Discovered: 1940
Discovered By: Glenn T. Seaborg

Electron Configuration

[Rn] 5f6 7s2

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f6

Ionisation Energies (kJ/mol)

1. 584.7

Elements near Plutonium

Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.