About radium

With atomic number 88, radium (Ra) has 88 protons in its nucleus and 88 electrons as a neutral atom. It is an alkaline earth metal in group 2, period 7, s-block. Radium was first discovered in 1898. Radium is a solid at room temperature, melting at 700 °C and boiling at 1140 °C.

Radium electron configuration

The electron configuration of radium is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s², or in short [Rn] 7s². Its electrons occupy 7 shells: K = 2, L = 8, M = 18, N = 32, O = 18, P = 8, Q = 2. Radium has 2 valence electrons in the Q shell (7s²), which is why it sits in group 2. When it forms cations, electrons leave the outermost subshell first: Ra²⁺ = [Rn] (like radon).

Filling order: 1s²(2) → 2s²(4) → 2p⁶(10) → 3s²(12) → 3p⁶(18) → 4s²(20) → 3d¹⁰(30) → 4p⁶(36) → 5s²(38) → 4d¹⁰(48) → 5p⁶(54) → 6s²(56) → 4f¹⁴(70) → 5d¹⁰(80) → 6p⁶(86) → 7s²(88)

Uses of radium

In industry and the laboratory, radium turns up in many places, for example Ra-223 therapy for prostate cancer that has spread to bone; formerly luminous watch dials.

Safety

Radium is radioactive. Using, storing or transporting radioactive material requires a licence from the national regulator (BAPETEN in Indonesia). Always read the safety data sheet (SDS) before working with a chemical.

Other elements in group 2

Frequently asked questions

What is the electron configuration of radium?

The electron configuration of radium (Ra, atomic number 88) is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s², or [Rn] 7s² in short. By shell: 2, 8, 18, 32, 18, 8, 2.

How many valence electrons does radium have?

Radium has 2 valence electrons.

Which group and period is radium in?

Radium is in group 2, period 7, s-block.

What is the atomic mass of radium?

Radium has no stable isotope, so the mass number of its longest-lived isotope, [226], is given.