Interactive Periodic Table of Elements
All 118 elements with relative atomic mass, electron configuration and properties. Select a cell to see details.
- Relative atomic mass
- 15.999
- Molar mass
- 15.999 g/mol
- Group · period · block
- 16 · 2 · p
- State at 20 °C
- Gas
- Electronegativity
- 3.44
- Atomic radius
- 60 pm
Electron configuration: [He] 2s² 2p⁴
How to read the periodic table
- 1Atomic number — the number of protons in the nucleus.
- 2Symbol — one or two letters, the same in every language.
- 3Element name (UK spelling: aluminium, sulfur, caesium).
- 4Relative atomic mass, rounded as on the GCSE data sheet.
- 5Period — a horizontal row. Its number is the number of electron shells.
- 6Group — a vertical column. Elements in a group react in similar ways.
Element groups
Revising for GCSE Chemistry?
Work through the periodic table, moles and ionic equations with a tutor. Your first lesson is a free trial.
Frequently asked questions
118 confirmed elements, from hydrogen (1) to oganesson (118). The last four were named in 2016.
Take the relative atomic mass and add the unit g/mol. For a compound, add up every atom: M(H₂O) = 2 × 1 + 16 = 18 g/mol.
A period is a row; its number equals the number of electron shells. A group is a column of elements with the same number of outer electrons.
To keep the table narrow. They belong to periods 6 and 7 and fill the f sub-shell.
Group 18: helium, neon, argon, krypton, xenon and radon. They have full outer shells and are very unreactive.
Yes, a periodic table is printed on the GCSE Chemistry data sheet. Practise with the same rounding.