Mg 12

Magnesium (Mg)

alkaline-earth-metal

Period: 3 Group: 2 Block: s

Solid

Standard Atomic Weight

Electron configuration

[Ne] 3s²

Melting point

649.85 °C (923 K)

Boiling point

1089.85 °C (1363 K)

Density

1740 kg/m³

Oxidation states

0, +1, +2

Electronegativity (Pauling)

1.31

Ionization energy (1st)

Discovery year

1755

Atomic radius

150 pm

Details

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

Discovery country England

Discoverers Sir Humphrey Davy

Magnesium is a light alkaline earth metal and a major rock-forming element. It occurs in silicate minerals, carbonates, evaporites, seawater, and brines, almost entirely as Mg²⁺ rather than as native metal. Its low density, ready formation of stable salts, and high affinity for oxygen shape both its metallurgy and its geochemistry. Magnesium is also essential in biology, where it stabilizes phosphate chemistry and is central to chlorophyll.

Magnesium is a light, silvery-white, and fairly tough metal. It tarnishes slightly in air, and finely divided magnesium readily ignites upon heating in air and burns with a dazzling white flame.

The name derives from Magnesia, a district in the north-eastern region of Greece called Thessalia. The Scottish chemist Joseph Black recognized it as a separate element in 1755. In 1808, the English chemist Humphry Davy obtained the impure metal, and in 1831 the French pharmacist and chemist Antoine- Alexandre Brutus Bussy isolated the metal in the pure state.

Although it is the eighth most abundant element in the universe and the seventh most abundant element in the earth's crust, magnesium is never found free in nature. Magnesium was first isolated by Sir Humphry Davy, an English chemist, through the electrolysis of a mixture of magnesium oxide (MgO) and mercuric oxide (HgO) in 1808. Today, magnesium can be extracted from the minerals dolomite (CaCO3·MgCO3) and carnallite (KCl·MgCl2·6H2O), but is most often obtained from seawater. Every cubic kilometer of seawater contains about 1.3 billion kilograms of magnesium (12 billion pounds per cubic mile).

From Magnesia, district in Thessaly. Compounds of magnesium have long been known. Black recognized magnesium as an element in 1755. Davy isolated it in 1808 and Bussy prepared it in coherent form in 1831. Magnesium is the eighth most abundant element in the earth's crust. It does not occur uncombined, but is found in large deposits in the form of magnesite, dolomite, and other minerals.

Read about Magnesium on Wikipedia

Images

Properties

Physical

Atomic radius (empirical) 150 pm

Covalent radius 141 pm

Van der Waals radius 173 pm

Metallic radius 136 pm

Density

Molar volume 0.014 L/mol

Phase at STP solid

Melting point 649.85 °C

Boiling point 1089.85 °C

Thermal conductivity 156 W/(m·K)

Specific heat capacity 1.023 J/(g·K)

Molar heat capacity 24.869 J/(mol·K)

Crystal structure hcp

Chemical

Electronegativity (Pauling) 1.31

Electronegativity (Allen) 1.293

Electron affinity

Ionization energy (1st)

Ionization energy (2nd)

Ionization energy (3rd)

Ionization energy (4th)

Ionization energy (5th)

Oxidation states 0, +1, +2

Valence electrons 2

Electron configuration

Electron configuration (semantic)

Thermodynamic

Heat of fusion 0.08788931 eV

Heat of vaporization 1.326631 eV

Heat of sublimation 1.524589 eV

Heat of atomization 1.524589 eV

Atomization enthalpy

Nuclear

Stable isotopes 3

Discovery year 1755

Abundance

Abundance (Earth's crust) 2.330e+4 mg/kg

Abundance (ocean)

Reactivity

N/A

Crystal Structure

Lattice constant a 321 pm

Electronic Structure

Electrons per shell 2, 8, 2

Identifiers

CAS number 7439-95-4

Term symbol

InChI InChI=1S/Mg

InChI Key FYYHWMGAXLPEAU-UHFFFAOYSA-N

Electron Configuration Measured

Ion charge

Protons 12

Electrons 12

Charge Neutral

Configuration Mg: 3s²

[Ne] 3s²

1s² 2s² 2p⁶ 3s²

Orbital diagram

↑↓

2/2

↑↓

2/2

↑↓

6/6

↑↓

2/2

Total electrons: 12 Unpaired: 0

Atomic model

Protons 12

Neutrons 12

Electrons 12

Mass number 24

Stability Stable

Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.

Schematic atomic model, not to scale.

Atomic Fingerprint

Emission / Absorption Spectrum

Emission Visible: 380–750 nm

Isotope Distribution

Mass number	Atomic mass (u)	Natural abundance	Half-life
24 Stable	23.985041697 ± 0.000000014	78.9900%	Stable
25 Stable	24.985836976 ± 0.00000005	10.0000%	Stable
26 Stable	25.982592968 ± 0.000000031	11.0100%	Stable

Measured

Phase / State

Solid 25 °C (298.15 K)

Reason: 624.9 °C below melting point (649.85 °C)

Melting point 649.85 °C

Boiling point 1089.85 °C

Below melting by 624.9 °C

0 K Current temperature: 25 °C 6000 K

Phase timeline

Schematic, not to scale

Solid

Liquid

Gas

Melting

Boiling

25°C

Solid

Liquid

Gas

Current

Phase transition points

Melting point Literature

649.85 °C

Boiling point Literature

1089.85 °C

Current phase Calculated
Solid

Transition energies

Heat of fusion Literature

0.08788931 eV

Energy required to melt 1 mol at melting point

Heat of vaporization Literature

1.326631 eV

Energy required to vaporize 1 mol at boiling point

Heat of sublimation Literature

1.524589 eV

Energy required to sublime 1 mol at sublimation point

Density

Reference density Literature

1740 kg/m³

At standard conditions

Current density Calculated

1740 kg/m³

At standard conditions

Atomic Spectra

Showing 10 of 12 Atomic Spectra. Sorted by ion charge (ascending).

Lines Holdings ?

Ion	Charge	Total lines	Transition probabilities	Level designations
Mg I	0	1342	1090	1342
Mg II	+1	601	482	601
Mg III	+2	452	149	452
Mg IV	+3	821	625	821
Mg V	+4	518	513	515
Mg VI	+5	890	883	890
Mg VII	+6	379	344	379
Mg VIII	+7	944	941	944
Mg IX	+8	461	444	461
Mg X	+9	223	184	223

NIST Lines Holdings →

Levels Holdings ?

Ion	Charge	Levels
Mg I	0	323
Mg II	+1	149
Mg III	+2	114
Mg IV	+3	173
Mg V	+4	104
Mg VI	+5	120
Mg VII	+6	104
Mg VIII	+7	113
Mg IX	+8	94
Mg X	+9	60

NIST Levels Holdings →

12 Mg 24.3055

Magnesium — Atomic Orbital Visualizer

[Ne]3s2

Energy levels 2 8 2

Oxidation states 0, +1, +2

HOMO 3s n=3 · l=0 · m=0

Magnesium — Atomic Orbital Visualizer Preview

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12 Mg 24.3055

Magnesium — Crystal Structure Visualizer

Primitive Hexagonal · Pearson hP2

Experimental

Pearson hP2

Coord. № 12

Packing 75.499%

Magnesium — Crystal Structure Visualizer Preview

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Ionic Radii

Charge	Coordination	Spin	Radius
+2	4	N/A	56.99999999999999 pm
+2	5	N/A	66 pm
+2	6	N/A	72 pm
+2	8	N/A	89 pm

Compounds

24.305 u

Mg+2

24.305 u

27.984 u

26.984 u

24.986 u

Mg+2

27.984 u

Mg+2

24.986 u

23.985 u

25.983 u

Isotopes (3)

Mass number	Atomic mass (u)	Natural abundance	Half-life	Decay mode
24 Stable	23.985041697 ± 0.000000014	78.9900% ± 0.0400%	Stable	stable
25 Stable	24.985836976 ± 0.00000005	10.0000% ± 0.0100%	Stable	stable
26 Stable	25.982592968 ± 0.000000031	11.0100% ± 0.0300%	Stable	stable

24 Stable

Atomic mass (u) 23.985041697 ± 0.000000014

Natural abundance 78.9900% ± 0.0400%

Half-life Stable

Decay mode

stable

25 Stable

Atomic mass (u) 24.985836976 ± 0.00000005

Natural abundance 10.0000% ± 0.0100%

Half-life Stable

Decay mode

stable

26 Stable

Atomic mass (u) 25.982592968 ± 0.000000031

Natural abundance 11.0100% ± 0.0300%

Half-life Stable

Decay mode

stable

Spectral Lines

Showing 50 of 399 Spectral Lines. Only spectral lines with measured intensity are shown by default.

Wavelength (nm)	Intensity	Ion stage	Type	Transition	Accuracy	Source
518.36043 nm	45	Mg I	emission	3s.3p 3P* → 3s.4s 3S	Measured	NIST
517.26844 nm	44	Mg I	emission	3s.3p 3P* → 3s.4s 3S	Measured	NIST
516.73213 nm	42	Mg I	emission	3s.3p 3P* → 3s.4s 3S	Measured	NIST
383.82919 nm	40	Mg I	emission	3s.3p 3P* → 3s.3d 3D	Measured	NIST
552.84047 nm	40	Mg I	emission	3s.3p 1P* → 3s.4d 1D	Measured	NIST
383.23039 nm	38	Mg I	emission	3s.3p 3P* → 3s.3d 3D	Measured	NIST
382.93547 nm	36	Mg I	emission	3s.3p 3P* → 3s.3d 3D	Measured	NIST
470.29908 nm	30	Mg I	emission	3s.3p 1P* → 3s.5d 1D	Measured	NIST
571.1088 nm	30	Mg I	emission	3s.3p 1P* → 3s.5s 1S	Measured	NIST
435.19057 nm	20	Mg I	emission	3s.3p 1P* → 3s.6d 1D	Measured	NIST
416.72713 nm	15	Mg I	emission	3s.3p 1P* → 3s.7d 1D	Measured	NIST
625.6757 nm	15	Mg III	emission	2s2.2p5.(2P<3/2>).4s 2[3/2] → 2s2.2p5.(2P*<3/2>).4p 2[5/2]	Measured	NIST
448.1126 nm	14	Mg II	emission	2p6.3d 2D → 2p6.4f 2F*	Measured	NIST
448.1325 nm	13	Mg II	emission	2p6.3d 2D → 2p6.4f 2F*	Measured	NIST
738.7689 nm	12	Mg I	emission	3s.3d 1D → 3s.8f 1F*	Measured	NIST
405.75052 nm	10	Mg I	emission	3s.3p 1P* → 3s.8d 1D	Measured	NIST
439.0572 nm	10	Mg II	emission	2p6.4p 2P* → 2p6.5d 2D	Measured	NIST
473.00286 nm	10	Mg I	emission	3s.3p 1P* → 3s.6s 1S	Measured	NIST
491.5991 nm	10	Mg III	emission	2s2.2p5.(2P<3/2>).4p 2[5/2] → 2s2.2p5.(2P<3/2>).4d 2[7/2]*	Measured	NIST
583.981 nm	10	Mg III	emission	2s2.2p5.(2P<3/2>).4s 2[3/2] → 2s2.2p5.(2P*<3/2>).4p 2[3/2]	Measured	NIST
631.8717 nm	10	Mg I	emission	3s.4s 3S → 3s.6p 3P*	Measured	NIST
634.6742 nm	10	Mg II	emission	2p6.4d 2D → 2p6.6f 2F*	Measured	NIST
719.3184 nm	10	Mg I	emission	3s.3d 1D → 3s.9f 1F*	Measured	NIST
729.1055 nm	10	Mg I	emission	3s.4s 1S → 3s.6p 1P*	Measured	NIST
438.4637 nm	9	Mg II	emission	2p6.4p 2P* → 2p6.5d 2D	Measured	NIST
443.3988 nm	9	Mg II	emission	2p6.4p 2P* → 2p6.6s 2S	Measured	NIST
452.6219 nm	9	Mg III	emission	2s2.2p5.(2P<3/2>).4p 2[1/2] → 2s2.2p5.(2P<3/2>).4d 2[3/2]*	Measured	NIST
459.6921 nm	9	Mg III	emission	2s2.2p5.(2P<3/2>).4p 2[1/2] → 2s2.2p5.(2P<3/2>).4d 2[1/2]*	Measured	NIST
496.041 nm	9	Mg III	emission	2s2.2p5.(2P<3/2>).4p 2[5/2] → 2s2.2p5.(2P<3/2>).4d 2[7/2]*	Measured	NIST
631.9237 nm	9	Mg I	emission	3s.4s 3S → 3s.6p 3P*	Measured	NIST
634.6964 nm	9	Mg II	emission	2p6.4d 2D → 2p6.6f 2F*	Measured	NIST
384.8211 nm	8	Mg II	emission	2p6.3d 2D → 2p6.5p 2P*	Measured	NIST
398.67533 nm	8	Mg I	emission	3s.3p 1P* → 3s.9d 1D	Measured	NIST
442.7994 nm	8	Mg II	emission	2p6.4p 2P* → 2p6.6s 2S	Measured	NIST
467.3315 nm	8	Mg III	emission	2s2.2p5.(2P<1/2>).4s 2[1/2] → 2s2.2p5.(2P*<1/2>).4p 2[1/2]	Measured	NIST
498.1469 nm	8	Mg III	emission	2s2.2p5.(2P<1/2>).4p 2[3/2] → 2s2.2p5.(2P<1/2>).4d 2[5/2]*	Measured	NIST
526.422 nm	8	Mg II	emission	2p6.4d 2D → 2p6.7f 2F*	Measured	NIST
640.6637 nm	8	Mg III	emission	2s2.2p5.(2P<3/2>).4s 2[3/2] → 2s2.2p5.(2P*<3/2>).4p 2[5/2]	Measured	NIST
678.7855 nm	8	Mg II	emission	2p6.5p 2P* → 2p6.7d 2D	Measured	NIST
681.927 nm	8	Mg II	emission	2p6.5p 2P* → 2p6.8s 2S	Measured	NIST
706.0414 nm	8	Mg I	emission	3s.3d 1D → 3s.10f 1F*	Measured	NIST
385.0386 nm	7	Mg II	emission	2p6.3d 2D → 2p6.5p 2P*	Measured	NIST
423.9473 nm	7	Mg III	emission	2s2.2p5.(2P<3/2>).4s 2[3/2] → 2s2.2p5.(2P*<1/2>).4p 2[1/2]	Measured	NIST
463.2537 nm	7	Mg III	emission	2s2.2p5.(2P<3/2>).4p 2[1/2] → 2s2.2p5.(2P<3/2>).4d 2[1/2]*	Measured	NIST
480.2585 nm	7	Mg III	emission	2s2.2p5.(2P<3/2>).4p 2[3/2] → 2s2.2p5.(2P<3/2>).4d 2[3/2]*	Measured	NIST
491.5363 nm	7	Mg III	emission	2s2.2p5.(2P<1/2>).4p 2[3/2] → 2s2.2p5.(2P<1/2>).4d 2[5/2]*	Measured	NIST
497.0497 nm	7	Mg III	emission	2s2.2p5.(2P<3/2>).4p 2[3/2] → 2s2.2p5.(2P<3/2>).4d 2[5/2]*	Measured	NIST
502.3674 nm	7	Mg III	emission	2s2.2p5.(2P<3/2>).4p 2[3/2] → 2s2.2p5.(2P<3/2>).4d 2[5/2]*	Measured	NIST
526.4364 nm	7	Mg II	emission	2p6.4d 2D → 2p6.7f 2F*	Measured	NIST
591.6431 nm	7	Mg II	emission	2p6.4d 2D → 2p6.7p 2P*	Measured	NIST

Extended Properties

Covalent Radii (Extended)

Covalent radius (Pyykkö)

Covalent radius (Pyykkö, double)

Covalent radius (Pyykkö, triple)

Covalent radius (Bragg)

Van der Waals Radii

Bondi

Batsanov

Alvarez

UFF

MM3

Atomic & Metallic Radii

Atomic radius (Rahm)

Metallic radius (C12)

Numbering Scales

Mendeleev

Pettifor

Glawe

Electronegativity Scales

Ghosh

Miedema

Gunnarsson–Lundqvist

Robles–Bartolotti

Polarizability & Dispersion

Dipole polarizability

Dipole polarizability (unc.)

C₆

C₆ (Gould–Bučko)

Chemical Affinity

Proton affinity

Gas basicity

Miedema Parameters

Miedema molar volume

Miedema electron density

Supply Risk & Economics

Production concentration

Relative supply risk

Reserve distribution

Political stability (top producer)

Political stability (top reserve)

Phase Transitions & Allotropes

Melting point	923.15 K
Boiling point	1363.15 K

Oxidation State Categories

+2 main

+1 extended

0 extended

Advanced Reference Data

Screening Constants (4)

n	Orbital	σ
1	s	0.3911
2	p	4.1742
2	s	4.608
3	s	8.6925

Crystal Radii Detail (4)

Charge	CN	r_crystal (pm)	Origin
2	IV	71
2	V	80
2	VI	86
2	VIII	103	calculated,

Isotope Decay Modes (43)

Isotope	Mode	Intensity
19	2p	100%
20	B+	100%
20	B+p	30.3%
21	B+	100%
21	B+p	20.1%
21	B+A	0.1%
21	B+pA	0%
22	B+	100%
23	B+	100%
27	B-	100%

X‑ray Scattering Factors (755)

Energy (eV)	f₁	f₂
0.5	0.117	0.14592
0.5079	0.1168	0.14896
0.516	0.1165	0.15206
0.5242	0.1165	0.15522
0.5325	0.1162	0.15845
0.5409	0.1162	0.16175
0.5495	0.1162	0.16511
0.5582	0.1161	0.16855
0.5671	0.1163	0.17205
0.5761	0.1167	0.17558

Additional Data

Estimated Crustal Abundance

The estimated element abundance in the earth's crust.

2.33×104 milligrams per kilogram

References (1)

[5] Magnesium https://education.jlab.org/itselemental/ele012.html

Estimated Oceanic Abundance

The estimated element abundance in the earth's oceans.

1.29×103 milligrams per liter

References (1)

[5] Magnesium https://education.jlab.org/itselemental/ele012.html

Sources

Sources of this element.

The metal is now principally obtained in the U.S. by electrolysis of fused magnesium chloride derived from brines, wells, and sea water.

References (1)

[6] Magnesium https://periodic.lanl.gov/12.shtml

References

(9)

1 PubChem

Data deposited in or computed by PubChem

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2 Atomic Mass Data Center (AMDC), International Atomic Energy Agency (IAEA)

The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.

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3 IUPAC Commission on Isotopic Abundances and Atomic Weights (CIAAW)

Magnesium

Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.

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4 IUPAC Periodic Table of the Elements and Isotopes (IPTEI)

The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.

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License note: Copyright (c) 2020 International Union of Pure and Applied Chemistry. The International Union of Pure and Applied Chemistry (IUPAC) contribution within Pubchem is provided under a CC-BY-NC-ND 4.0 license, unless otherwise stated.

5 Jefferson Lab, U.S. Department of Energy

Magnesium

Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/

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License note: Please see citation and linking information: https://education.jlab.org/faq/index.html

6 Los Alamos National Laboratory, U.S. Department of Energy

Magnesium

The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.

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7 NIST Physical Measurement Laboratory

Magnesium

The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database

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8 PubChem Elements

Magnesium

This section provides all form of data related to element Magnesium.

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9 PubChem Elements

Magnesium

The element property data was retrieved from publications.

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Last updated: May 1, 2026

Data verified: May 12, 2026

Content is reviewed against latest scientific data.