12
Mg
Magnesium
24.305
Magnesium (Mg)
Alkaline Earth MetalGroup 2Period 3s-block-block
Magnesium is a chemical element with symbol Mg and atomic number 12. It is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (Group 2, or alkaline earth metals) of the periodic table:they each have the same electron configuration in their outer electron shell producing a similar crystal structure. Magnesium is the ninth most abundant element in the universe.
Latin name: Magnesium
Atomic Number
12
Atomic Mass
24.305 g/mol
Phase (STP)
Solid
Electron Config.
[Ne] 3s²
General
SymbolMg
Atomic Number12
Atomic Mass24.305 g/mol
CategoryAlkaline Earth Metal
Group2
Period3
Blocks-block
Electron Configuration[Ne] 3s²
Valence Electrons2
ColourSilvery-white
Appearanceshiny grey solid
CAS NumberCAS7439-95-4
Physical Properties
Phase (STP)Solid
Density1.74 g/cm³
Melting Point649.85°C · 1201.73°F · 923.00 K
Boiling Point1089.85°C · 1993.73°F · 1363.00 K
Atomic Properties
Atomic Radius145 pm
Covalent Radius141 pm
Van der Waals Radius173 pm
Electronegativity1.31 Pauling
Ionization Energy738 kJ/mol
Electron Affinity0 kJ/mol
Oxidation States+1, +2
Ion ChargeMg²⁺
Thermodynamic
Molar Heat24.869 J/(mol·K)
Thermal Conductivity160 W/(m·K)
Electromagnetic
Electrical TypeConductor
Crystal Structure
Crystal StructureHexagonal close-packed
Mechanical Properties
Mohs Hardness2.5
Abundance
In Universe0.0600%
In Sun0.0700%
In Earth's Crust2.9000%
In Oceans0.1300%
In Humans0.0270%
In Meteorites12.0000%
Discovery & History
Discovery Year1755
Discovered ByJoseph Black
Isotopes of Magnesium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Mg-24 | 78.99% | Stable | — |
| Mg-25 | 10% | Stable | — |
| Mg-26 | 11.01% | Stable | — |