12 Mg Magnesium 24.305
Alkaline-earth metal
Magnesium 镁
[Ne] 3s²
- Period 3
- Group 2
- Block s
- Solid
Electron configuration
1s² 2s² 2p⁶ 3s²
Orbital diagram (valence)
3s ↑↓
- Electrons per shell
- 2, 8, 2
- Unpaired electrons
- 0
- Zeff (Slater)
- 2.85
Properties
- Atomic weight
- 24.305
- Electronegativity (Pauling)
- 1.31
- First ionization energy
- 737.7 kJ/mol
- Electron affinity
- no data
- Covalent radius
- 141 pm
- van der Waals radius
- 173 pm
- Melting point
- 923 K
- Boiling point
- 1363 K
- Density
- 1.74 g/cm³
- Melting / boiling point
- 649.9 °C / 1089.8 °C
- Common oxidation states
- +2
- Discovered
- 1808
Natural isotopes
| Mass number A | Atomic mass / u | Abundance |
|---|---|---|
| 24Mg | 23.985042 | 78.99 % |
| 25Mg | 24.985837 | 10.00 % |
| 26Mg | 25.982593 | 11.01 % |
Isotope masses: AME2020; abundances: IUPAC/CIAAW representative values.
Successive ionization energies
The big jumps appear where core electrons start to be removed. Ionization energies from the NIST Atomic Spectra Database.
Magnesium in the course
The lessons that discuss this element most (ranked by mentions).
- Complexometric titration: EDTA and water hardness Titrimetric and gravimetric analysis
- Ellingham diagrams and metal extraction Entropy and free energy
- Hydrogen and the s-block The main-group elements
- Periodic trends: size, ionization energy and electronegativity Atomic structure
- Extracting metals Transition metals
- Stability and the chelate effect Coordination chemistry
- Activities and the salt effect Precipitation and complex ions
- Selective precipitation and separating ions Precipitation and complex ions
Lab experiments with Magnesium
Periodic trend
Group 2
Data: PubChem periodic table (public domain); atomic weights are IUPAC abridged standard values; covalent radii from Cordero et al. (2008).