Element 12
Magnesium (Mg)
Magnesium (Mg) is element 12 of the periodic table, an alkaline earth metal in period 3, group 2 (s-block) with an atomic mass of 24.305 and is a solid at standard conditions.
At a glance
- Atomic number
- 12
- Symbol
- Mg
- Atomic mass
- 24.305 u
- Category
- Alkaline earth metals
- Period
- 3
- Group
- 2
- Block
- s-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2
- Shorthand configuration
- [Ne] 3s2
- Electrons per shell
- 2, 8, 2
- Oxidation states
- +1, +2
Physical properties
- Melting point
- 923 K (649.85 °C)
- Boiling point
- 1,363 K (1,089.85 °C)
- Density
- 1.738 g/cm³
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 1.31
- Atomic radius
- 145 pm
- Covalent radius
- 141 pm
- Van der Waals radius
- 173 pm
- First ionization energy
- 738 kJ/mol
- Electron affinity
- 0 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Mg-24 | 23.98504 | 78.99% | Stable |
Common uses
- Alloys
- Fireworks
- Medicine
- Photography
Discovery
- Year
- 1755
- Discovered by
- Joseph Black
- Country
- Scotland
Frequently asked questions
- Is magnesium a metal?
- Yes. Magnesium is a metal, classified as an alkaline earth metal on the periodic table.
- How many protons does magnesium have?
- Magnesium has 12 protons. Its atomic number is 12, which is also the number of electrons in a neutral atom of magnesium.
- What group and period is magnesium in?
- Magnesium is in group 2 and period 3 of the periodic table, in the s-block.
- What is the atomic mass of magnesium?
- The atomic mass of magnesium is 24.305 u (unified atomic mass units).
Keep exploring
Magnesium's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.