12 2 · 8 · 2

Magnesium, Mg, element 12

Alkaline earth metal· Period 3· Group 2· s-block

Configuration [Ne]3s²

Atomic weight: 24.305Da
Phase: solid
Density: 1.74g/cm³
Melting point: 923.15K 650 °C
Boiling point: 1,363.15K 1,090 °C
Electronegativity: 1.31

Silvery metallic element belonging to group 2 of the periodic table (alkaline-earth metals). It is essential for living organisms, and is used in a number of light alloys. Chemically very reactive, it forms a protective oxide coating when exposed to air and burns with an intense white flame. It also reacts with sulphur, nitrogen and the halogens. First isolated by Bussy in 1828. Description from mendeleev.

Back to the table

The outermost shell: the valence electronsThe inner shellsThe nucleus One bead for each electron, on the ring of its shell, counted from the nucleus out. The rings turn at their own pace; the model is Bohr's picture of the atom, which places electrons in shells but not on true orbits.

Atomic properties

4 of 5 fields have a value for magnesium

Atomic weight The standard atomic weight. For an element with no stable isotope, the mass of its longest-lived isotope.: 24.305Da; Source: mendeleev
Electron configuration: [Ne]3s²; Source: mendeleev
Electron configuration in full The electron configuration with the noble-gas core written out.: 1s²2s²2p⁶3s²; Source: Worked outfrom electron configuration
Electrons in each shell Counted from the electron configuration, from the first shell outward.: 2 · 8 · 2; Source: Worked outfrom electron configuration

No data uncertainty of the atomic weight.

Screening of each subshell

Clementi's screening constants: how much of the nucleus's charge the other electrons hide from an electron in each subshell. What is left is the effective nuclear charge it feels.

Subshell	Screening σ	Effective charge Z − σ
1s	0.3911	11.6089
2s	4.608	7.392
2p	4.1742	7.8258
3s	8.6925	3.3075