Magnesium (Mg)
Alkaline earth metal · s-block · period 3 · group 2
Lightweight, silvery-white metal.
Magnesium (symbol Mg) is chemical element number 12, a alkaline earth metal in group 2, period 3 of the periodic table. Its standard atomic weight is 24.305 and its electron configuration is [Ne] 3s2. At room temperature it is a solid. Burns with a dazzling white light — used in old flash photography and in flares.
Properties
| Atomic number | 12 |
|---|---|
| Atomic mass | 24.305 |
| Category | Alkaline earth metal |
| Block | s-block |
| Group · Period | 2 · 3 |
| Electron configuration | [Ne] 3s2 |
| Electrons per shell | 2, 8, 2 |
| State at 25 °C | solid |
| Melting point | 923 K |
| Boiling point | 1363 K |
| Density | 1.738 g/cm³ |
| Electronegativity (Pauling) | 1.31 |
| Radioactive | No |
| Origin | primordial |
| Discovered | 1755 · Joseph Black |
Key facts about Magnesium
- Burns with a dazzling white light — used in old flash photography and in flares.
- One of the lightest structural metals, about two-thirds the density of aluminium.
- At the centre of every chlorophyll molecule, so plants cannot photosynthesise without it.
- A vital dietary mineral for muscle and nerve function.
What Magnesium is used for
Lightweight alloys for cars and aircraft, flares and fireworks, sacrificial anodes, dietary supplements.
Where it sits in the periodic table
Magnesium is in group 2, period 3, of the s-block. Its electron configuration [Ne] 3s2 means its outermost shell holds 2 electrons, which is what places it here and explains much of its chemistry. See Magnesium on the interactive table →
Magnesium — frequently asked questions
What is Magnesium used for?
Lightweight alloys for cars and aircraft, flares and fireworks, sacrificial anodes, dietary supplements.
Is Magnesium radioactive?
No. Magnesium has at least one stable isotope and is not radioactive.
What is the electron configuration of Magnesium?
Magnesium has the electron configuration [Ne] 3s2, which is 2, 8, 2 electrons per shell.
What group and period is Magnesium in?
Magnesium is in group 2, period 3, in the s-block. Its outer shell holds 2 electrons.
Who discovered Magnesium?
Magnesium was discovered in 1755 by Joseph Black.