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Strontium (Sr)

Strontium is a chemical element of the periodic table with chemical symbol Sr and atomic number 38 with an atomic weight of 87.621 u and is classed as alkaline earth metal and is part of group 2 (alkaline earth metal). Strontium is solid at room temperature.

Strontium in the periodic table

Atomic number38
Group2 (Alkaline earth metal)
ClassificationAlkaline Earth Metal
Color Silver
Number of protons38 p+
Number of neutrons50 n0
Number of electrons38 e-
From Wikipedia, the free encyclopediaStrontium is a chemical element with symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when it is exposed to air.

Physical properties

Phase at STPSolid
Density2.64 g/cm3
Atomic weight87.621 u

Thermal properties

Melting point1050 K
776.85 °C
1430.33 °F
Boiling point1650 K
1376.85 °C
2510.33 °F
Heat of vaporization136.9 kJ/mol

Atomic properties

Electronegativity (Pauling Scale)0.95
Electron affinity5.023 kJ/mol
Oxidation states+1, +2
(a strongly basic oxide)
Ionization energies
  1. 549.5 kJ/mol
  2. 1064.2 kJ/mol
  3. 4138 kJ/mol
  4. 5500 kJ/mol
  5. 6910 kJ/mol
  6. 8760 kJ/mol
  7. 10230 kJ/mol
  8. 11800 kJ/mol
  9. 15600 kJ/mol
  10. 17100 kJ/mol
  11. 31270 kJ/mol

Electron configuration for strontium

Electron configuration
Shorthand configuration
[Kr] 5s2
Electron configuration
Full configuration
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2
Electron configuration chart
Electrons per shell2, 8, 18, 8, 2
Valence electrons 2
Valency electrons 2
Bohr model
StrontiumElectron shell for Strontium, created by Injosoft ABSr
Figure: Shell diagram of Strontium (Sr) atom.
Orbital Diagram

The history of Strontium

DiscoveryWilliam Cruickshank (1787)
First isolationHumphry Davy (1808)
Discovery of strontium
Both strontium and strontianite are named after Strontian, a village in Scotland near which the mineral was discovered in 1790 by Adair Crawford and William Cruickshank; it was identified as a new element the next year from its crimson-red flame test color. The element was eventually isolated by Sir Humphry Davy in 1808 by the electrolysis of a mixture containing strontium chloride and mercuric oxide, and announced by him in a lecture to the Royal Society on 30 June 1808. In keeping with the naming of the other alkaline earths, he changed the name to strontium.


List of unique identifiers for Strontium in various chemical registry databases
CAS Number7440-24-6
ChemSpider ID4514263
EC number231-133-4
PubChem CID Number5359327