Periodic Table

Magnesium

Alkaline Earth Metal

Quick Facts about Magnesium

Na
  • solid- state of matter at room temperature
  • Stable- has at least one stable isotope
  • +2- common oxidation states in compounds
  • HEX- crystal structure, atomic arrangement in solid form
Al

Magnesium (Mg) is element 12 on the periodic table. Atomic mass of Mg: 24.3050 u. Mg is in period 3, group 2. Melting point of Mg: 923.00 K.Density of Mg: 1.74 g/cm³.

Why Magnesium Matters

The element in chlorophyll that makes plants green

In Your Home

  • Epsom salts for baths (magnesium sulfate)
  • Antacids (milk of magnesia)
  • Magnesium fire starters
  • Lightweight alloys in laptop cases

Industry Uses

AutomotiveLightweight alloys for wheels and engine blocks
AerospaceMagnesium alloys in aircraft and missiles
AgricultureFertilizer component, central atom in chlorophyll
MedicalLaxatives, antacids, IV magnesium for eclampsia

In Your Body

✓ Essential for life

Essential for 300+ enzyme reactions. Central atom of chlorophyll. Needed for muscle and nerve function, blood sugar control, and DNA synthesis. Your body contains about 25g.

Safety: Very safe from food sources. Excess from supplements causes diarrhea (milk of magnesia effect). IV overdose can cause heart problems.

Discovery of Magnesium

Discovered by Sir Humphrey Davy in England, 1808

Name origin: From Magnesia ancient city in district of Thessaly, Greece.

History & Events

1755
Recognition
Joseph Black recognized magnesia as a distinct element (different from lime)
1808
Isolation
Humphry Davy isolated magnesium metal through electrolysis
1915
Chlorophyll Structure
Richard Willstätter determined chlorophyll's structure with magnesium at center, winning Nobel Prize

About Magnesium

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.

Atomic Properties of Mg

Atomic Number of Mg
12
Atomic Mass of Mg
24.3050 u
Electron Configuration
[Ne] 3s2
Electronegativity
1.31
Block
s-block
Group
2
Period
3

Physical Properties of Mg

Phase (STP)
solid
Melting Point of Mg
923.00 K
Boiling Point of Mg
1363.00 K
Density of Mg
1.7380 g/cm3

Thermal Properties

Heat of Fusion
9.20 kJ/mol
Heat of Vaporization
131.80 kJ/mol
Specific Heat
1.02 J/g·K
Molar Heat Capacity
24.87 J/mol·K
Thermal Conductivity
156.00 W/m·K

Atomic Radii

Calculated
150 pm
Covalent
139 pm
Van der Waals
173 pm
Metallic
136 pm

Common Misconceptions

Wrong:Magnesium burns underwater.
Correct:Magnesium can burn in steam but not underwater. It reacts with water slowly at room temperature.
Wrong:Magnesium supplements are all the same.
Correct:Different forms (citrate, oxide, glycinate) have very different absorption rates and effects.
Wrong:Green vegetables are green because of magnesium.
Correct:Partially true! Chlorophyll contains magnesium, but the green color comes from chlorophyll's structure, not magnesium itself.

Isotopes of Magnesium

Magnesium has 3 naturally occurring isotopes.

IsotopeAtomic Mass (u)AbundanceHalf-LifeDecay Mode
2412Mg (Mg-24)Magnesium-24 isotope23.985041778.99%
2512Mg (Mg-25)Magnesium-25 isotope24.9858369810.00%
2612Mg (Mg-26)Magnesium-26 isotope25.9825929711.01%

Data source: NIH PubChem (aggregated from IUPAC, NIST)

Isotope Applications

Isotopes of Magnesium have important real-world applications in science and industry.

Geochronology & Dating

26Mg is a stable isotope and is the radiogenic product of 26Al decay. 26Al is produced by cosmic rays in space and in the atmosphere, and it was present in the primordial solar nebula. The anomalous abundance of 26Mg in meteorite inclusions indicate that this material must have been formed early in the development of the Solar System before all primordial 26Al (with half-life of 7.1×105 years) had decayed [116].

Abundance

Earth's Crust
23.3 g/kg
Seawater
1.3 g/kg

Uses

Used in alloys to make airplanes, missiles and other uses for light metals. Has structural properties similar to aluminium. But since it is flammable at temperatures of burning gasoline, its uses are limited.

Sources

Usually obtained by electrolysis of melted magnesium chloride (MgCl2) found in sea water. Each cubic mile of seawater contains about 12 billion pounds of magnesium.

Geochemistry

Goldschmidt
litophile
Geochemical Class
major

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