038Alkaline earth metal · Group 2 · Period 5
Strontium
Strontium (Sr) is element 38, a alkaline earth metal in the s-block — group 2, period 5. It is a solid at room temperature with 5 electron shells (2, 8, 18, 8, 2) and an atomic mass of 87.621 u.
- Atomic mass
- 87.62 u
- Phase · STP
- solid
- Melting
- 1050 K · 777 °C
- Boiling
- 1650 K · 1377 °C
- Electronegativity
- 0.95
- Density
- 2.64 g/cm³
Photograph — Jurii, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons, source: https://images-of-elements.com/strontium.php
Identity
- Atomic number
- 38
- Standard atomic weight
- 87.62 u
- Category
- Alkaline earth metal
- Group
- 2 · Alkaline earth metals
- Period
- 5
- Block
- s-block
- Oxidation states
- +2
Physical properties
- Melting point
- 1050 K · 777 °C
- Boiling point
- 1650 K · 1377 °C
- Density
- 2.64 g/cm³
- Molar heat capacity
- 26.4 J/(mol·K)
- Atomic radius
- 249 pm
- Electron affinity
- 5.023 kJ/mol
Atomic structure
38protons
50neutrons
38electrons
2valence e⁻
- Noble-gas notation
- [Kr] 5s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2
- Electrons per shell
- 2, 8, 18, 8, 2
Periodic trends
Where Strontium ranks across all 118 elements.
Ionization energies
Energy to remove each successive electron (kJ/mol).
549.51
1.1k2
4.1k3
5.5k4
6.9k5
8.8k6
10.2k7
11.8k8
15.6k9
17.1k10
Successive ionization energies (kJ/mol, log scale).
Discovery
- Discovered
- 1790
- Discovered by
- William Cruickshank (chemist)
- Named by
- —
- Appearance
- —