Element 88 · Radium (Ra)

Radium Bohr model: diagram and electrons per shell

The radium Bohr model shows a radium atom (Ra) as a small nucleus with its electrons circling it in 7 shells: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O, 8 in shell P and 2 in shell Q. This page has a rotating 3D radium Bohr model, a flat diagram, a table of the electrons in each shell and the steps to draw it yourself.

Rotate the radium Bohr model in 3D

Drag to orbit, scroll to zoom.

This is a Bohr model of radium (Ra), a simplified picture of a single radium atom. Its nucleus holds 88 protons, and a neutral radium atom has 88 electrons, arranged around it in 7 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O, 8 in shell P and 2 in shell Q).

Ra K · 21s² L · 82s² 2p⁶ M · 183s² 3p⁶ 3d¹⁰ N · 324s² 4p⁶ 4d¹⁰ 4f¹⁴ O · 185s² 5p⁶ 5d¹⁰ P · 86s² 6p⁶ Q · 27s²

Radium Bohr model diagram

Bohr model diagram of radium: a nucleus of 88 protons with 88 electrons on 7 shells, 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O, 8 in shell P and 2 in shell Q, each ring labelled with its shell letter. — The radium Bohr model drawn flat: each ring is a shell, labelled with its letter, and every dot is an electron (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O, 8 in shell P and 2 in shell Q).

Radium electrons per shell

A neutral radium atom has 88 electrons, one for each of its 88 protons. They fill the shells from the nucleus outwards: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O, 8 in shell P and 2 in shell Q.

Electrons in each shell of the radium Bohr model
Shell	Shell number (n)	Electrons	Most it can hold (2n²)	Subshells
K	1	2	2	1s²
L	2	8	8	2s² 2p⁶
M	3	18	18	3s² 3p⁶ 3d¹⁰
N	4	32	32	4s² 4p⁶ 4d¹⁰ 4f¹⁴
O	5	18	50	5s² 5p⁶ 5d¹⁰
P	6	8	72	6s² 6p⁶
Q	7	2	98	7s²

How the radium Bohr model builds up, shell by shell

Watch the radium Bohr model come together: the nucleus first, then each shell in turn, from the innermost outwards, with its electrons joining the ring. The legend names every shell and counts its electrons, so you can read off the arrangement (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O, 8 in shell P and 2 in shell Q) as it forms.

Animation of the radium Bohr model being built: a nucleus of 88 protons appears first, then each shell grows in around it and takes its electrons, giving 88 electrons on 7 shells (2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O, 8 in shell P and 2 in shell Q). — The radium Bohr model built up in six seconds: the nucleus first, then each shell with its electrons, ending with 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O, 8 in shell P and 2 in shell Q. Protons are red, neutrons yellow and electrons blue.

How to draw the radium Bohr model

Find the atomic number. Radium has atomic number 88, so a neutral atom has 88 protons and 88 electrons.
Draw the nucleus. Put a circle in the centre and write Ra in it. The 88 protons sit there with the neutrons.
Draw the shells. Sketch 7 shells as rings around the nucleus. A shell holds at most 2n² electrons: 2 in the first, 8 in the second, 18 in the third and 32 in the fourth.
Place the electrons. Fill from the inside out: 2 in shell K, 8 in shell L, 18 in shell M, 32 in shell N, 18 in shell O, 8 in shell P and 2 in shell Q.
Check the total. 2 + 8 + 18 + 32 + 18 + 8 + 2 = 88, the atomic number, so every electron is accounted for.

Atomic data for the radium Bohr model

The numbers behind the radium Bohr model, grouped by topic. Radii are in picometres (pm) and energies in kilojoules per mole (kJ/mol).

Identity

Symbol: Ra
Atomic number: 88
Atomic mass: [226] u
Family: Alkaline Earth Metals
Position: group 2, period 7
Block: s-block

Electron configuration

Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s²
Shorthand: [Rn] 7s²
Electrons per shell: 2, 8, 18, 32, 18, 8, 2
Outer-shell electrons: 2 in shell Q

Ionisation energies

I₁: 509.3
I₂: 979

Energy to remove each electron in turn (kJ/mol). A sharp jump means the next electron comes from an inner shell.

Atomic radii

Empirical (pm): 215
Covalent (pm): 201
Van der Waals (pm): 283

Electronegativity and electron affinity

Electronegativity (Pauling): 0.9
Electron affinity (kJ/mol): 9.649

Oxidation states

Charges the element commonly takes in compounds.

Physical properties, abundance and history of radium

Bulk properties of radium, how common it is, who discovered it and some of its compounds.

Physical properties

Phase at room conditions: Solid
Appearance: Silvery white metallic
Melting point: 959.85°C (1233 K)
Boiling point: 1736.85°C (2010 K)
Density: 5.5 g/cm³
Heat of fusion (kJ/mol): 9.6
Heat of vaporisation (kJ/mol): 113

Abundance

Earth's crust (mg/kg): 0
Oceans (mg/L): 0

Discovery

Discovered by: Pierre Curie
Year: 1898

Common compounds

Radium-226 Ra
Radium Ra
Radium-223 Ra
Radium nitrate NO3Ra-
Radium isotope of mass 227 Ra
Radium-228 Ra
Radium-233 Ra
Radium-224 Ra

Compounds listed in the PubChem database.

Main isotopes of radium

Isotopes of radium share the same 88 protons but differ in neutrons. Natural isotopes come first, then the longest-lived others.

Main isotopes of radium: mass number, abundance, half-life and decay
Mass number	Natural abundance	Half-life	Decay
223	–	11.435 d	α, 14C
224	–	3.632 d	α, 14C
225	–	14.82 d	β⁻
226	–	1.6 ky	α, 14C, 2β⁻
228	–	5.75 y	β⁻
230	–	93 min	β⁻

α = alpha decay, β⁻ = beta-minus, β⁺ = beta-plus, EC = electron capture, SF = spontaneous fission, p / n = proton / neutron emission.

More about radium

Radium on the periodic table – properties, isotopes, uses and the full radium page.
Alkaline Earth Metals – all alkaline earth metal elements and their trends.
Bohr model of every element – the Bohr model of all 118 elements.