Radium

Element 88 on the periodic table, symbol Ra, group 2, period 7.

Radium is a chemical element with symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is almost colorless, but it readily combines with nitrogen (rather than oxygen) on exposure to air, forming a black surface layer of radium nitride (Ra3N2).

Appearance: silvery white metallic

Properties

Atomic Number: 88
Atomic Mass: 226.0000 u
Group: 2
Period: 7
Block: s-block
Category: Alkaline Earth Metal
State at 25 °C: Solid
Melting Point: 1,233 K · 959.9 °C
Boiling Point: 2,010 K · 1,736.9 °C
Density: 5.5 g/cm³
Atomic Radius: 215 pm
Electronegativity: 0.9
Oxidation States: +2
Abundance in Crust: 9.00e-7 mg/kg
Discovered: 1898
Discovered By: Pierre Curie

Electron Configuration

[Rn] 7s2

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

Ionisation Energies (kJ/mol)

1. 509.3
2. 979

Elements near Radium

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.