Magnesium (Mg): electron configuration, atomic mass and facts
Magnesium (Mg) is element 12 of the periodic table, an alkaline earth metal in period 3, group 2. Its electron configuration is [Ne] 3s2, with electrons arranged in shells 2, 8, 2, and its standard atomic weight is 24.305 u.
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▶ Watch Magnesium’s electrons orbit in the interactive periodic tableMagnesium at a glance
| Symbol | Mg |
|---|---|
| Atomic number | 12 |
| Atomic mass | 24.305 u |
| Category | Alkaline earth metal |
| Group | 2 |
| Period | 3 |
| Block | s-block |
| Electron configuration | 1s2 2s2 2p6 3s2 |
| Noble-gas shorthand | [Ne] 3s2 |
| Electrons per shell | 2, 8, 2 |
| Outer-shell electrons | 2 |
| Electronegativity (Pauling) | 1.31 |
| State at 20 °C | solid |
Where is Magnesium on the periodic table?
Magnesium is in period 3, group 2, in the s-block. The period number matches its 3 electron shells, and the block names the subshell its last electrons fill. In the same group, Beryllium sits directly above it and Calcium sits directly below it. Elements in one group have the same number of outer-shell electrons (2 here), which is why they react in similar ways.
How to work out the electron configuration of Magnesium
Put 12 electrons into subshells in order of rising energy, filling each before starting the next: 1s² (2), 2s² (4), 2p⁶ (10), 3s² (12). In shorthand, [Ne] stands for the 10 electrons of neon, giving [Ne] 3s².
How electronegative is Magnesium?
Magnesium has a Pauling electronegativity of 1.31, ranking 61 of the 100 elements with a known value (fluorine is highest at 3.98). That is low: it tends to give up electrons and form positive ions.
Magnesium in the virtual lab
Faradium’s chemistry workbench includes these chemicals that contain magnesium: Magnesium ribbon, Magnesium sulfate. Open the Chemistry Lab to experiment with them.
Frequently asked questions
What is the electron configuration of Magnesium?
The electron configuration of Magnesium (Mg) is 1s2 2s2 2p6 3s2. In noble-gas shorthand it is written [Ne] 3s2.
How many electrons does Magnesium have in each shell?
Magnesium has 12 electrons arranged in shells as 2, 8, 2. It has 2 electrons in its outer shell.
What is the atomic mass of Magnesium?
The standard atomic weight of Magnesium is 24.305 u, so one mole of Magnesium atoms has a mass of about 24.305 g.
Is Magnesium a metal?
Yes. Magnesium is an alkaline earth metal.
Explore nearby elements
More alkaline earth metals: Beryllium, Calcium, Strontium, Barium, Radium. See all elements on the periodic table.