Strontium (Sr) – element 38
Strontium is a chemical element with the symbol Sr and atomic number 38. It is a alkaline earth metal in group 2 (alkaline earth metals), period 5 of the periodic table (s-block), and is a solid at room temperature.
Strontium (Sr) has atomic number 38, atomic mass 87.62 u and electron configuration [Kr] 5s2.
Strontium facts
| Symbol | Sr |
|---|---|
| Atomic number | 38 |
| Atomic mass | 87.62 u (g/mol) |
| Category | alkaline earth metal |
| Group | group 2 (alkaline earth metals) |
| Period | 5 |
| Block | s-block |
| Phase at 20 °C | Solid |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 |
| Noble-gas notation | [Kr] 5s2 |
| Electrons per shell | 2, 8, 18, 8, 2 |
| Valence electrons | 2 |
Bohr model and shells
Strontium has 38 electrons in 5 shells: 2, 8, 18, 8, 2. Full configuration and noble-gas notation are in the table; work out any element or ion with the electron configuration calculator.
Physical and atomic properties
| Melting point | 1050 K (776.9 °C) |
|---|---|
| Boiling point | 1650 K (1376.8 °C) |
| Density | 2.64 g/cm³ |
| Electronegativity (Pauling) | 0.95 |
| Electron affinity | 5.023 kJ/mol |
| Ionization energies | 549.5, 1064.2, 4138 kJ/mol (1st, 2nd, 3rd) |
| Molar heat capacity | 26.4 J/(mol·K) |
| Discovered by | William Cruickshank (chemist) |
Use the atomic mass in the molar mass calculator for any formula containing Sr.
Position in the periodic table
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Frequently asked questions
What is the atomic mass of strontium?
The atomic mass of strontium is 87.62 u, so one mole of strontium atoms weighs 87.62 g.
What is the electron configuration of strontium?
Strontium has 38 electrons: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s², or [Kr] 5s² in noble-gas notation. Electrons per shell: 2, 8, 18, 8, 2.
How many valence electrons does strontium have?
Strontium has 2 valence electrons (group 2).
Is strontium a metal?
Yes. Strontium is a alkaline earth metal.
Where is strontium on the periodic table?
Strontium is in group 2 (alkaline earth metals), period 5, in the s-block.
Data: Periodic-Table-JSON (CC BY-SA 3.0); standard atomic weights from IUPAC (abridged). Values in brackets are the mass number of the longest-lived isotope.