Magnesium
Element 12 · Alkaline Earth Metal
Magnesium is the metal of brilliant light: photographers once burned magnesium flash powder, and fireworks still use it for its dazzling white flame. It is the eighth most abundant element in Earth's crust and the third most abundant dissolved in seawater. Biology claimed it early — a single magnesium atom sits at the center of every chlorophyll molecule, catching sunlight for photosynthesis. Engineers prize magnesium for being one-third lighter than aluminium, casting it into car parts, laptops, and aircraft components, while doctors prescribe its compounds as antacids and laxatives.
Key facts
| Atomic number | 12 |
|---|---|
| Atomic weight | 24.305 |
| Category | Alkaline Earth Metal |
| Group / Period | 2 / 3 |
| Block | s |
| Electron configuration | 1s2 2s2 2p6 3s2 |
| Common oxidation states | +2 |
| State at STP | Solid |
| Electronegativity | 1.31 |
| Atomic radius | 145 pm |
| Density | 1.738 g/cm³ |
| Melting point | 650 °C |
| Boiling point | 1090 °C |
Occurrence
Magnesium abounds in the minerals dolomite and magnesite and dissolves in seawater at about 0.13 percent. Plants pull it from soil to build chlorophyll.
Applications
Lightweight alloys for cars and aircraft
Fireworks and flares
Chlorophyll in plants
Antacids (milk of magnesia)
Epsom salts (MgSO4)
Common compounds
- Magnesium oxide (MgO)
- Magnesium hydroxide (Mg(OH)2)
- Epsom salt (MgSO4·7H2O)
- Dolomite (CaMg(CO3)2)
Chlorophyll holds one magnesium atom at its center — swap it for iron and you get heme, the red pigment of blood.
Data source: IUPAC standard atomic weights 2021