Sr
Strontium
Element 38 · Alkaline earth metal
Strontium (Sr)
Strontium is a soft, silvery alkaline earth metal. Its salts give fireworks and flares their crimson red colour.
- Alkaline earth metal
- Period 5
- Group 2
- s-block
- solid at room temperature
Key properties
- Atomic mass
- 87.62
- u
- Electron configuration
- [Kr] 5s2
- Melting point
- 776.9 °C
- 1,050 K
- Boiling point
- 1,381.9 °C
- 1,655 K
- Density
- 2.64 g/cm³
- Electronegativity
- 0.95
- Pauling
- Atomic radius
- 249 pm
- van der Waals
- 1st ionisation energy
- 5.695 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about strontium
- 01
Humphry Davy isolated the metal in 1808 by electrolysis.
- 02
Radioactive strontium-90 from nuclear fallout can replace calcium in bones.
- 03
Strontium aluminate makes glow-in-the-dark paints far brighter than older phosphors.
Applications
What is strontium used for?
- Red fireworks and flares
- Glow-in-the-dark materials
- Ferrite magnets
- Toothpaste for sensitive teeth
History
Discovery & name origin
Discovered by
Year
Where
Scotland
Name origin
From Strontian, a village in Scotland where the mineral was found.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 38
- Atomic mass
- 87.62 u
- Group
- 2
- Period
- 5
- Block
- s-block
- Electron configuration
- [Kr] 5s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2
- Electrons per shell
- 2, 8, 18, 8, 2
- Electronegativity (Pauling)
- 0.95
- Electron affinity
- —
- Atomic radius (van der Waals)
- 249 pm
- Stable isotopes
- 4
Oxidation states
Highlighted: common oxidation states (+2).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st549.5
- 2nd1,064.2
- 3rd4,138
- 4th5,500
- 5th6,910
- 6th8,760
- 7th10,230
- 8th11,800
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 1,050 K · 776.9 °C · 1,430.3 °F
- Boiling point
- 1,655 K · 1,381.9 °C · 2,519.3 °F
- Density
- 2.64 g/cm³
- Molar heat capacity
- 26.4 J/(mol·K)
- Appearance
- —
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Strontium questions
What is Sr on the periodic table?
Sr is the symbol for strontium, element 38 on the periodic table. It sits in group 2, period 5, in the alkaline earth metal category, and has an atomic mass of 87.62.
What is the atomic number of strontium?
Strontium has atomic number 38, so every strontium atom has 38 protons in its nucleus. Its symbol is Sr and its atomic mass is 87.62.
Who discovered strontium?
Strontium was discovered by Adair Crawford in 1790 (Scotland). The name comes from from Strontian, a village in Scotland where the mineral was found.
What is strontium used for?
Strontium is used for: red fireworks and flares; glow-in-the-dark materials; ferrite magnets; toothpaste for sensitive teeth.
Is strontium a metal?
Yes. Strontium is a alkaline earth metal, one of the metallic elements.
What is the electron configuration of strontium?
The electron configuration of strontium is [Kr] 5s2. Its 38 electrons are arranged in shells as 2, 8, 18, 8, 2.