Mg
Magnesium
Element 12 · Alkaline earth metal
Magnesium (Mg)
Magnesium is a light, strong alkaline earth metal that burns with a brilliant white flame. It sits at the heart of every chlorophyll molecule.
- Alkaline earth metal
- Period 3
- Group 2
- s-block
- solid at room temperature
Key properties
- Atomic mass
- 24.305
- u
- Electron configuration
- [Ne] 3s2
- Melting point
- 649.9 °C
- 923 K
- Boiling point
- 1,089.9 °C
- 1,363 K
- Density
- 1.74 g/cm³
- Electronegativity
- 1.31
- Pauling
- Atomic radius
- 173 pm
- van der Waals
- 1st ionisation energy
- 7.646 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about magnesium
- 01
Humphry Davy first isolated the metal in 1808, after Joseph Black recognised it as an element.
- 02
Burning magnesium cannot be put out with water — the hot metal splits water and releases hydrogen.
- 03
An adult human body contains about 25 g of magnesium, mostly in the bones.
Applications
What is magnesium used for?
- Lightweight alloys for cars and laptops
- Fireworks and flares
- Antacids and laxatives
- Desulfurising steel
History
Discovery & name origin
Discovered by
Year
Where
Scotland
Name origin
From Magnesia, a district in Thessaly, Greece.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 12
- Atomic mass
- 24.305 u
- Group
- 2
- Period
- 3
- Block
- s-block
- Electron configuration
- [Ne] 3s2
- Full configuration
- 1s2 2s2 2p6 3s2
- Electrons per shell
- 2, 8, 2
- Electronegativity (Pauling)
- 1.31
- Electron affinity
- —
- Atomic radius (van der Waals)
- 173 pm
- Stable isotopes
- 3
Oxidation states
Highlighted: common oxidation states (+2).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st737.7
- 2nd1,450.7
- 3rd7,732.7
- 4th10,542.5
- 5th13,630
- 6th18,020
- 7th21,711
- 8th25,661
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 923 K · 649.9 °C · 1,201.7 °F
- Boiling point
- 1,363 K · 1,089.9 °C · 1,993.7 °F
- Density
- 1.74 g/cm³
- Molar heat capacity
- 24.869 J/(mol·K)
- Appearance
- Shiny grey solid
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Magnesium questions
What is Mg on the periodic table?
Mg is the symbol for magnesium, element 12 on the periodic table. It sits in group 2, period 3, in the alkaline earth metal category, and has an atomic mass of 24.305.
What is the atomic number of magnesium?
Magnesium has atomic number 12, so every magnesium atom has 12 protons in its nucleus. Its symbol is Mg and its atomic mass is 24.305.
Who discovered magnesium?
Magnesium was discovered by Joseph Black in 1755 (Scotland). The name comes from from Magnesia, a district in Thessaly, Greece.
What is magnesium used for?
Magnesium is used for: lightweight alloys for cars and laptops; fireworks and flares; antacids and laxatives; desulfurising steel.
Is magnesium a metal?
Yes. Magnesium is a alkaline earth metal, one of the metallic elements.
What is the electron configuration of magnesium?
The electron configuration of magnesium is [Ne] 3s2. Its 12 electrons are arranged in shells as 2, 8, 2.