Magnesium Facts – Mg or Atomic Number 12

Magnesium (Mg) is a silvery-white, lightweight metal and the 12th element on the periodic table. As an alkaline earth metal, it is highly reactive and does not occur freely in nature. Magnesium is the eighth most abundant element in Earth’s crust, comprising about 2.3% by weight, and is the fifth most plentiful element dissolved in seawater. Essential to both industrial applications and biological systems, magnesium plays a critical role in structural alloys, chemical processes, and over 300 enzymatic reactions in the human body.

Basic Magnesium Facts

Name: Magnesium

Atomic Number: 12

Element Symbol: Mg

Group: 2

Period: 3

Block: s

Element Family: alkaline earth

Atomic Mass: [24.304, 24.307]
IUPAC guidelines recommend an atomic mass range. If a single value of the atomic mass is necessary, use 24.305.

Electron Configuration: [Ne]3s² (shorthand) or 1s²2s²2p⁶3s² (full)

Discovery and Isolation

Magnesium was first recognized as a distinct element in the early 19th century. The mineral magnesia alba (magnesium carbonate), sourced from Magnesia, a region in Thessaly, Greece, had been known since ancient times, but it was often confused with calcium-containing compounds due to similar properties.

In 1755, Joseph Black identified magnesium carbonate as distinct from calcium carbonate by studying their reactions with acids and heat. However, he did not isolate the element itself.

The element magnesium was first isolated in 1808 by Sir Humphry Davy, who used electrolysis to reduce a mixture of magnesia (MgO) and mercuric oxide (HgO). Although Davy’s initial yield was impure, he confirmed the existence of a new metallic element and named it “magnium”, later corrected to magnesium.

Pure magnesium metal was finally obtained in 1831 by Antoine Bussy, who improved the isolation process by heating magnesium chloride with potassium. His method produced small, coherent quantities of magnesium metal, enabling the first studies of its properties as a distinct substance.

Name Origin: Davy named the element after its source material, magnesia.

Appearance and Physical Properties

Magnesium is a silvery-white metal with a shiny luster when freshly cut. However, it quickly tarnishes in air due to the formation of a thin, protective layer of magnesium oxide (MgO). It is a lightweight, moderately hard metal with a low density and high strength-to-weight ratio.

Physical Properties:

• Color: Silvery-white
• Density: 1.738 g/cm³ (about two-thirds that of aluminum)
• Melting Point: 650 °C (1,202 °F)
• Boiling Point: 1,090 °C (1,994 °F)
• Thermal conductivity: Relatively high
• Electrical conductivity: Moderate, similar to aluminum

Magnetic Properties:

Magnesium is diamagnetic, meaning it creates a very weak, negative response to external magnetic fields and does not retain magnetization. It is not attracted to magnets.

Mechanical Properties:

• Malleability and ductility: Moderate when pure, but greatly improved in alloyed forms
• Hardness: Relatively soft (Mohs hardness ≈ 2.5)
• Tensile strength: Low in pure form, higher in alloys
• Machinability: Excellent, especially for magnesium alloys
• Burning behavior: Burns easily when powdered or in thin strips, producing an intense white flame

Because of its light weight and mechanical strength when alloyed, magnesium is widely used in structural applications, particularly where weight reduction is important.

Isotopes

Natural magnesium consists of three stable isotopes: ²⁴Mg, ²⁵Mg and ²⁶Mg. By far, the most abundant isotope is ²⁴Mg. Nineteen radioactive isotopes have been produced under laboratory conditions ranging from ¹⁹Mg to ⁴⁰Mg.

²⁴Mg
Magnesium-24 is a stable isotope containing 12 neutrons. 78.99% of natural magnesium is magnesium-24.

²⁵Mg
Magnesium-25 is a stable isotope containing 13 neutrons. 10% of natural magnesium is magnesium-25.

²⁶Mg
Magnesium-26 is a stable isotope containing 14 neutrons. 11.01% of natural magnesium is magnesium-26.

Magnesium Uses

Magnesium is valued for its low density, high strength-to-weight ratio, and excellent reactivity, making it useful across many industries and applications:

• Aerospace and Automotive: Magnesium alloys are prized for being lightweight yet strong, making them ideal for aircraft components, automotive parts such as steering wheels and engine blocks, and performance bicycles.
• Electronics and Consumer Products: Magnesium is used in the manufacture of laptops, smartphones, cameras, and power tools due to its strength and lightness.
• Construction and Metallurgy: Magnesium oxide is used in refractory bricks and specialty cements. Metallic magnesium is also employed as a deoxidizer and desulfurizer in steelmaking and in the production of titanium and other metals.
• Pyrotechnics and Flares: Magnesium burns with a brilliant white light, making it a key component in fireworks, signal flares, and incendiary devices.
• Medical Applications: Magnesium is used in some surgical implants and biodegradable medical devices due to its biocompatibility and ability to safely dissolve in the body over time.
• Chemical Processes: It serves as a reducing agent in the production of uranium and other metals from their salts and is involved in various chemical synthesis applications.

Abundance and Sources

Magnesium is the eighth most abundant element in Earth’s crust, making up about 2.3% by weight. It is also the fifth most abundant element dissolved in seawater, following oxygen, hydrogen, chlorine, and sodium.

Magnesium does not occur in its elemental form in nature but occurs in a variety of minerals and salts. Key sources include:

• Minerals: Dolomite, magnesite, brucite, carnallite, and olivine are the most commercially important magnesium-bearing minerals.
• Seawater and Brines: Magnesium extraction from seawater and brine pools involves precipitation and electrolysis.
• Mining and Refining: Commercial production typically involves mining magnesite or dolomite and reducing magnesium oxide using silicon or electrolysis.

Major producers of magnesium include China, Russia, the United States, and Israel.

Health Effects and Toxicity

Magnesium is essential for human health. It is a cofactor in more than 300 enzymatic reactions and plays a vital role in nerve transmission, muscle contraction, protein synthesis, blood glucose regulation, and blood pressure control.

The recommended daily intake for adults is between 310 and 420 milligrams, depending on age and sex. Magnesium is in many foods, including leafy greens, whole grains, nuts, legumes, and dairy products. Many individuals fall short of meeting their daily magnesium needs, which may lead to symptoms such as:

• Muscle cramps or spasms
• Fatigue and weakness
• Irregular heartbeat
• Mood disturbances or anxiety
• High blood pressure

Magnesium toxicity from food sources is extremely rare, as the kidneys excrete excess amounts. However, overuse of magnesium-containing supplements or medications, such as antacids or laxatives, causes adverse effects. Symptoms of excessive magnesium intake include:

• Nausea and vomiting
• Diarrhea
• Low blood pressure
• Confusion or slowed reflexes
• In severe cases, cardiac arrest

People with kidney disease are especially vulnerable to magnesium overload and should consult a healthcare provider before taking supplements.

Oxidation States

Magnesium primarily exhibits a +2 oxidation state in its compounds. This is because magnesium has two valence electrons in its outer shell (electron configuration: [Ne] 3s²), which it readily loses to achieve a stable noble gas configuration. The loss of these two electrons forms the Mg²⁺ ion, which is highly stable and common in both inorganic and biological systems.

Key Points:

• Common oxidation state: +2
• Electron configuration of Mg: [Ne] 3s²
• Mg²⁺ ion: Stable, colorless, and prevalent in ionic compounds

Examples of Magnesium Compounds in the +2 State:

• Magnesium oxide (MgO)
• Magnesium chloride (MgCl₂)
• Magnesium sulfate (MgSO₄)
• Magnesium hydroxide (Mg(OH)₂)

The +1 and 0 oxidation states occur in certain organometallic or cluster compounds under laboratory conditions, but these are rare and unstable.

Physical Data

Density: 1.74 g/cm³

Melting Point: 923 K ​(650 °C, ​1202 °F)

Boiling Point: 1363 K ​(1091 °C, ​1994 °F)

State at 20ºC: Solid

Heat of Fusion: 8.48 kJ/mol

Heat of Vaporization: 128 kJ/mol

Molar Heat Capacity: 24.869 J/mol·K

Magnetic Ordering: Paramagnetic

Crystal Structure: hexagonal close-packed (hcp)

Atomic Data

Atomic Radius: 1.6 Å

Covalent Radius: 1.41 Å

Van der Waals Radius:  1.73 Å

Electron Affinity: not stable

Electronegativity: 1.31

1^st Ionization Energy: 737.75 kJ/mol

2^nd Ionization Energy: 1450.683 kJ/mol

3^rd Ionization Energy: 7732.692 kJ/mol

4^th Ionization Energy: 10542.519 kJ/mol

5^th Ionization Energy: 13630.48 kJ/mol

6^th Ionization Energy: 18019.6 kJ/mol

7^th Ionization Energy: 21711.13 kJ/mol

8^th Ionization Energy: 25661.24 kJ/mol

Oxidation States: 0, +1, +2

Interesting Magnesium Facts

• Magnesium is a silvery-white alkaline solid at room temperature.
• Magnesium has a sour taste. Small amounts of magnesium in mineral water gives it that slightly tangy flavor.
• An early name for magnesium was “magnium”. The metallic form of manganese was already known as magnesium. Davy’s colleagues convinced him to change the name to magnesium, while manganese metal was just called manganese.
• Magnesium is a central atom in the chlorophyll molecule. It is an essential part of the process of photosynthesis.
• Magnesium is the ninth most abundant element in the universe.
• Magnesium is the 11th most abundant element in the human body. There is magnesium in every one of your cells.
• 60% of the magnesium in your body is in your skeletal system.
• Magnesium burns very brightly and produces white sparkles in fireworks.
• Adding magnesium to aluminum alloys reduces their weight.
• Magnesium is common in some fire starters that produce sparks when rubbed with steel.
• Magnesium hydroxide additions in some plastics helps make them fire resistant.
• A class of organic magnesium compounds known as Grignard reagents are important compounds in synthesis reactions in organic chemistry. These compounds take the form: RMg-X, where R is a carbon functional group and X is a halide.

Learn more about elements on the periodic table.

References

• Amundsen, Ketil; Aune, Terje Kr.; Bakke, Per; et al. (2003). “Magnesium”. Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim, Germany: Wiley. doi:10.1002/14356007.a15_559. ISBN 978-3-527-30385-4.
• Davy, H. (1808). “Electro-chemical researches on the decomposition of the earths; with observations on the metals obtained from the alkaline earths, and on the amalgam procured from ammonia”. Philosophical Transactions of the Royal Society of London. 98: 333–370. doi:10.1098/rstl.1808.0023
• Rösch, B.; Gentner, T. X.; Eyselein, J.; Langer, J.; Elsen, H.; Harder, S. (2021). “Strongly reducing magnesium(0) complexes”. Nature. 592 (7856): 717–721. doi:10.1038/s41586-021-03401-w
• Rumble, John R., ed. (2018). CRC Handbook of Chemistry and Physics (99th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-1385-6163-2.
• Saris, N.E.; Mervaala, E.; Karppanen, H.; Khawaja, J.A.; Lewenstam, A. (2000). “Magnesium. An update on physiological, clinical and analytical aspects”. Clin Chim Acta. 294 (1–2): 1–26. doi:10.1016/S0009-8981(99)00258-2