Strontium (Sr)
Strontium is element 38, a alkaline earth metal in period 5, group 2 of the periodic table. At room temperature it is a solid.
Electron configuration [Kr] 5s2
Electrons per shell 2, 8, 18, 8, 2
Strontium data
| Atomic number | 38 |
|---|---|
| Symbol | Sr |
| Atomic mass | 87.62 u |
| Category | Alkaline earth metal |
| Group | 2 |
| Period | 5 |
| Block | s |
| State at 25 °C | solid |
| Melting point | 1050 K (776.9 °C) |
| Boiling point | 1655 K (1381.9 °C) |
| Density | 2.63 g/cm³ |
| Electronegativity (Pauling) | 0.95 |
| Atomic radius | 192 pm |
| 1st ionization energy | 550 kJ/mol |
| Electron affinity | -5 kJ/mol |
| Oxidation states | +2 |
| Common ion charge | 2+ |
| Discovered | 1790 |
Orbital diagram
Each box is one orbital holding up to two electrons of opposite spin. Following Hund’s rule, electrons spread out singly across a subshell before pairing.
Work through strontium’s configuration and its ions →
Where strontium sits
Strontium belongs to the alkaline earth metals. Its Pauling electronegativity of 0.95 is among the lowest on the table, so it gives up electrons readily; see the electronegativity chart and periodic trends for context. To use its mass in a calculation, try the molar mass calculator.
Strontium FAQ
What is the electron configuration of strontium?
Strontium (Z = 38) has the configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 5s2. In noble-gas shorthand that is [Kr] 5s2.
How many valence electrons does strontium have?
2 (outer shell (n = 5)).
What is the atomic mass of strontium?
The standard atomic weight of strontium is 87.62 u, so one mole weighs 87.62 g.
Is strontium a metal?
Yes. Strontium is a alkaline earth metal.
What is the charge of a strontium ion?
Strontium most commonly forms Sr2+.