Strontium (Sr): Electron Configuration, Properties and Uses
Strontium (Sr): Electron Configuration, Properties and Uses
Electron configuration [Kr] 5s2 · group 2 · period 5 · Ar 87.62
Strontium data
- Atomic number
- 38
- Relative atomic mass
- 87.62
- Group
- 2
- Period
- 5
- Block
- s
- Category
- Alkaline earth metal
- Electron configuration
- [Kr] 5s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2
- Electrons per shell
- 2, 8, 18, 8, 2 (K L M N O)
- Valence electrons
- 2
- Electronegativity (Pauling)
- 0.95
- First ionisation energy
- 5.695 eV
- Atomic radius (van der Waals)
- 249 pm
- State at room temperature
- Solid
- Melting point
- 777 °C
- Boiling point
- 1382 °C
- Density
- 2.64 g/cm³
- Common oxidation states
- +2
- Discovered
- 1790
Source: PubChem (NIH, accessed 13 Nov 2026); atomic mass: IUPAC standard atomic weight.
Electron shell diagram
K 2 · L 8 · M 18 · N 8 · O 2
Orbital diagram (outer electrons)
About strontium
Strontium, symbol Sr, is element number 38 in the periodic table. It is an alkaline earth metal in group 2, period 5, s-block. Strontium was first discovered in 1790. Strontium is a solid at room temperature, melting at 777 °C and boiling at 1382 °C.
Strontium electron configuration
The electron configuration of strontium is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2, or in short [Kr] 5s2. Its electrons occupy 5 shells: K = 2, L = 8, M = 18, N = 8, O = 2. Strontium has 2 valence electrons in the O shell (5s2), which is why it sits in group 2. When it forms cations, electrons leave the outermost subshell first: Sr2+ = [Kr] (like krypton).
Filling order: 1s2(2) → 2s2(4) → 2p6(10) → 3s2(12) → 3p6(18) → 4s2(20) → 3d10(30) → 4p6(36) → 5s2(38)
Uses of strontium
Well-known applications of strontium include red fireworks and flares, and ferrite magnets. For research and analysis you can browse strontium compounds in the AMI Scientific catalogue.
Safety
Strontium metal is generally safe to handle, but avoid breathing its dust and read the SDS before using Strontium compounds. 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 strontium?
The electron configuration of strontium (Sr, atomic number 38) is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2, or [Kr] 5s2 in short. By shell: 2, 8, 18, 8, 2.
How many valence electrons does strontium have?
Strontium has 2 valence electrons.
Which group and period is strontium in?
Strontium is in group 2, period 5, s-block.
What is the atomic mass of strontium?
The relative atomic mass of strontium is 87.62. Use it to calculate molar mass with the molar mass calculator.
Need strontium compounds for your lab?
AMI Scientific is one of the official TCI distributors in Indonesia. Reagents with lot CoA & SDS, formal quotations and tax invoices for universities and laboratories.
Other formulas & calculators: molarity, mole, molality, normality, dilution, titration, pH, buffer, molar mass, ppm, mole fraction, mass percent, periodic table, chemical MSDS.
