ElementsWhat is strontium?
Strontium is a soft, silvery-yellow metal. Its salts give a strong red colour to flames.
What is strontium used for?
Red fireworks and flares, magnets for small motors and loudspeakers, and some toothpastes for sensitive teeth.
Where the name comes from
From Strontian, a village in Scotland where its mineral was found.
Key facts
- Symbol
- Sr
- Atomic number
- 38
- Atomic mass
- 87.62 u
- Family
- Alkaline earth metal
- Period
- 5
- Group
- 2
- Block
- s
- State at room temperature
- Solid
- Melting point
- 776.9 °C (1,050 K, 1,430 °F)
- Boiling point
- 1,382 °C (1,655 K, 2,519 °F)
- Density
- 2.64 g/cm³
- Electrons per shell
- 2, 8, 18, 8, 2
- Electron configuration
- [Kr]5s2
- Common oxidation states
- +2
- Electronegativity (Pauling)
- 0.95
- First ionisation energy
- 5.695 eV
- Electron affinity
- no value
- Atomic radius (van der Waals)
- 249 pm
- Discovered
- 1790
Place in the periodic table
Strontium is element number 38. It sits in period 5 (row 5) of the periodic table, in group 2 (column 2), and belongs to the s-block. Just before it comes rubidium (37), and just after it comes yttrium (39). In the same column, calcium is above it and barium is below it. Elements in one column tend to behave alike.
Family: Alkaline earth metals.
Physical properties
At room temperature strontium is a solid. It melts at 776.9 °C and boils at 1,382 °C, so it stays liquid over a range of 605 degrees. Its density is 2.64 grams per cubic centimetre, so a one-litre block would weigh about 2.64 kilograms. By density it ranks 72nd among the 96 elements with a measured value.
Inside the atom
An atom of strontium has 38 protons in its nucleus and, when neutral, 38 electrons around it. The electrons are arranged in 5 shells: 2, 8, 18, 8, 2. The outermost shell holds 2 electrons. Written in full, the electron configuration is [Kr]5s2.
Its electronegativity on the Pauling scale is 0.95. This number shows how strongly an atom pulls shared electrons towards itself: fluorine, the strongest, is 3.98. Removing one electron from an atom takes 5.695 electronvolts (about 549 kilojoules per mole). One mole of strontium weighs 87.62 grams, so a single gram contains about 6.87 × 1021 atoms.
The ring picture is a simple model that only counts the electrons in each shell. Real atoms do not look like this.
Next steps
- Work out the weight of a compound that contains strontium with the molar mass calculator.
- Compare it with every other element in the sortable list.
- Test yourself with the symbol quiz.
Figures on this page are from PubChem (U.S. National Library of Medicine), as downloaded on 11 November 2026. See About and data sources.