All practice pages/Interatomic theory/Elements
Element 12, an alkaline earth metal
A light metal that burns with a dazzling white light, and the atom at the center of every chlorophyll molecule.
Period 3, group 2. The other alkaline earth metals are tinted, and every cell opens its own article.
Magnesium has 12 electrons, one for every proton, so the atom carries no charge. Below are the same 12 electrons written two ways.
1s² 2s² 2p⁶ 3s²
Short form: [Ne] 3s², where [Ne] stands for the 10 electrons neon already has.
The simple form counts electrons shell by shell. The orbital form says which subshell each one sits in: s holds 2, p holds 6, d holds 10 and f holds 14. Shell 2 here is 2s² 2p⁶, and 2 + 6 is 8.
Magnesium sits in period 3 and has 3 shells. The period number counts the shells.
The outer shell holds 2 electrons. Those are the ones magnesium can lose, gain or share, so they are the ones that decide what it bonds with. For a main-group element the group number gives that count: group 2 means 2.
Two valence electrons, which magnesium gives up to form the Mg²⁺ ion in its compounds.
About 2% of the crust, in minerals such as dolomite, magnesite and olivine. Seawater holds about 1.3 grams per liter, and for decades much of the world's magnesium was extracted from the sea. Today China produces most of it.
Joseph Black recognized magnesia as different from lime in 1755, and Humphry Davy isolated an impure sample of the metal in 1808. The name comes from Magnesia, a district in Greece where magnesium minerals were found.
Light alloys for car parts, laptop and camera bodies, bicycles and aircraft, since magnesium is about a third lighter than aluminum. It also goes into aluminum drink cans, flares and fireworks, and the production of iron and titanium. Epsom salt soothes sore muscles and milk of magnesia settles stomachs.
Burning magnesium is so hot that water makes the fire worse by releasing hydrogen, and the light can hurt your eyes. Fine powder and shavings catch fire easily.