Radium (Ra)

Element 88 · alkaline earth metal · group 2, period 7

• 88 protons
• 2 valence e−
• +2
• s-block

Properties

Electron configuration of radium

Orbitals fill from the lowest energy upward. Writing that out for radium gives 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 7s², which is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 7s2 in plain text.

Everything up to Rn is the same as in that noble gas, so it is usually abbreviated to [Rn] 7s². The part outside the bracket is what does the chemistry.

Radium ion charge

Radium commonly forms ions with a charge of +2.

It has 2 valence electrons, so it is 6 short of a full octet and 2 above an empty outer shell. An atom takes whichever route is shorter, which is why the charge comes out as it does.

Common questions

How many valence electrons does radium have?

Radium has 2 valence electrons. For groups 1 and 2 the count is the group number, and radium is in group 2.

What is the electron configuration of radium?

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 7s2, or [Rn] 7s2 written from the previous noble gas. Orbitals fill lowest energy first.

What is the charge of radium?

Radium commonly forms ions with a charge of +2. With 2 valence electrons it is 6 short of an octet and 2 above an empty shell, so it takes whichever route is shorter.

How many protons, electrons and neutrons does radium have?

A neutral radium atom has 88 protons and 88 electrons. Its standard atomic weight is 226, so the most common isotope has about 138 neutrons.

Nearby elements

• Barium (Ba)above it in group 2
• Francium (Fr)one place to its left
• Actinium (Ac)one place to its right
• Beryllium (Be)same group, same valence count
• Magnesium (Mg)same group, same valence count
• Calcium (Ca)same group, same valence count

See the ionic charge of every element →