Magnesium (Mg)
Magnesium is element 12, a alkaline earth metal in period 3, group 2 of the periodic table. At room temperature it is a solid.
Electron configuration [Ne] 3s2
Electrons per shell 2, 8, 2
Magnesium data
| Atomic number | 12 |
|---|---|
| Symbol | Mg |
| Atomic mass | 24.305 u |
| Category | Alkaline earth metal |
| Group | 2 |
| Period | 3 |
| Block | s |
| State at 25 °C | solid |
| Melting point | 923 K (649.9 °C) |
| Boiling point | 1363 K (1089.9 °C) |
| Density | 1.738 g/cm³ |
| Electronegativity (Pauling) | 1.31 |
| Atomic radius | 130 pm |
| 1st ionization energy | 738 kJ/mol |
| Electron affinity | 0 kJ/mol |
| Oxidation states | +1, +2 |
| Common ion charge | 2+ |
| Discovered | 1808 |
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 magnesium’s configuration and its ions →
Where magnesium sits
Magnesium belongs to the alkaline earth metals. Its Pauling electronegativity of 1.31 is mid-range; see the electronegativity chart and periodic trends for context. To use its mass in a calculation, try the molar mass calculator.
Magnesium FAQ
What is the electron configuration of magnesium?
Magnesium (Z = 12) has the configuration 1s2 2s2 2p6 3s2. In noble-gas shorthand that is [Ne] 3s2.
How many valence electrons does magnesium have?
2 (outer shell (n = 3)).
What is the atomic mass of magnesium?
The standard atomic weight of magnesium is 24.305 u, so one mole weighs 24.305 g.
Is magnesium a metal?
Yes. Magnesium is a alkaline earth metal.
What is the charge of a magnesium ion?
Magnesium most commonly forms Mg2+.