Element 38 · Alkaline earth metal
Strontium (Sr) — Element 38
Strontian, Scotland
Strontium (Sr) is an alkaline earth metal in Period 5, Group 2 of the periodic table with atomic number 38, standard atomic weight 87.62 u, and ground-state electron configuration [Kr] 5s². At standard temperature and pressure it is classified as a solid with 2 valence electrons and common oxidation states +2.
Fireworks (red), magnets
What are the atomic properties and physical constants of Strontium?
Reference constants compiled from IUPAC standard atomic weights, the NIST Atomic Spectra Database, and the CRC Handbook.
- Atomic number (Z)
- 38
- Standard atomic mass
- 87.62 u
- Chemical family
- Alkaline earth metal
- Ground-state configuration
- [Kr] 5s²
- Electrons per shell
- 2, 8, 18, 8, 2
- Valence electrons
- 2
- Common ion charges / oxidation states
- +2
- Phase at STP
- Solid
- Pauling electronegativity
- 0.95 Pauling
- First ionization energy
- 549 kJ/mol
- Atomic radius
- 219 pm
- Melting point
- 777 °C
- Boiling point
- 1,382 °C
- Discovery year
- 1790
- Table coordinate
- Period 5, Group 2
- Radioactivity
- Has stable isotope(s)
How are electrons arranged across Strontium’s shells?
A neutral Strontium atom contains 38 electrons distributed across 5 occupied principal energy shells ([Kr] 5s²). The table below compares Strontium’s shell occupancy against each shell’s theoretical 2n² capacity.
| Principal Shell (n) | Spectroscopic Letter | Electrons in Sr | Max Shell Capacity (2n²) |
|---|---|---|---|
| n = 1 | K | 2 e⁻ | 2 e⁻ |
| n = 2 | L | 8 e⁻ | 8 e⁻ |
| n = 3 | M | 18 e⁻ | 18 e⁻ |
| n = 4 | N | 8 e⁻ | 32 e⁻ |
| n = 5 | O | 2 e⁻ | 50 e⁻ |
Frequently Asked Questions about Strontium (Sr)
What is the atomic mass and atomic number of Strontium (Sr)?
Strontium (Sr) has atomic number Z = 38 (38 protons in its nucleus) and an IUPAC standard atomic weight of 87.62 u. It sits in Period 5, Group 2 and is classified as an alkaline earth metal.
What is the ground-state electron configuration of Strontium?
The neutral ground-state electron configuration of Strontium (Z = 38) is [Kr] 5s². Across its 5 occupied principal shells (n = 1 to n = 5), the electrons per shell are 2, 8, 18, 8, 2, with 2 valence electrons participating in bonding.
What are the common ion charges and electronegativity of Strontium?
Strontium commonly forms +2 oxidation states or ion charges in compounds. Its Pauling electronegativity is 0.95 and its first ionization energy is 549 kJ/mol.
When was Strontium discovered and what is it used for?
Strontium was discovered in 1790 (Strontian, Scotland). Fireworks (red), magnets
How does Strontium compare to neighboring elements?
Other alkaline earth metal elements: