Magnesium (Mg)
“The feather-light metal whose white-hot flame once fired every camera flash — and still lights fireworks and emergency flares.”
How its electrons are arranged
Computed from the aufbau principle, with known real-world exceptions applied automatically.
Characteristics
- Configuration 1s² 2s² 2p⁶ 3s² — two valence electrons, so magnesium belongs to Period 3, Group 2, the alkaline earth metals, and reacts as the Mg²⁺ ion.
- Burns with a famously dazzling white flame: 2Mg + O₂ → 2MgO — the light that once lit photographs and still fills flares and fireworks.
- So hungry for oxygen that a burning ribbon keeps burning inside carbon dioxide, tearing O from CO₂ and leaving specks of black carbon: 2Mg + CO₂ → 2MgO + C.
- One Mg²⁺ ion sits at the heart of every chlorophyll molecule — remove the magnesium and the green factory of photosynthesis shuts down.
A silvery-white, fairly soft metal — the lightest of all structural metals, about two-thirds the density of aluminium. Shavings catch flame readily, and a thin ribbon burns with a light too bright to watch directly, leaving fluffy white ash of magnesium oxide.
Where you meet it
✦ Uses
- Fireworks, sparklers and distress flares — magnesium powder is the classical recipe for brilliant white bursts in the night sky.
- Milk of magnesia, Mg(OH)₂ — the milky antacid stocked in Bangladeshi pharmacies for acidity and indigestion.
- Epsom salt (MgSO₄·7H₂O) — a fertiliser for magnesium-hungry crops like tomatoes and citrus, and a classic bath salt for aching muscles.
- Magnesium-aluminium alloys — light casings for laptops, cameras, ladders and car wheels, plus sacrificial anodes that corrode away to protect ships and pipelines.
◍ Everyday examples
- A plate of shak — palong, lal shak, dhonepata — the green of every leaf is chlorophyll built around a magnesium ion.
- Fireworks at a wedding or on Shab-e-Barat — the blinding white sparks are magnesium burning.
- The white, milky medicine bottle at home for stomach acidity — shake it and you hold magnesium hydroxide.
History & name
In 1755 the Scottish chemist Joseph Black proved that the white powder “magnesia alba” was a substance distinct from lime, so chemists suspected an unknown metal waited inside. In 1808 Humphry Davy passed current through a hot mixture of magnesia and mercury oxide and collected an impure magnesium amalgam; only in 1829 did the Frenchman Antoine Bussy obtain clean metal by passing potassium vapour over magnesium chloride. The name lands us in ancient Greece: Magnesia was a district of Thessaly whose minerals also fathered the words “magnet” and “manganese”.