magnesium

• Description
• General information
• Physical data
• Radii
• Electronegativities
• Solid state structure
• Temperatures
• Enthalpies
• Ionization Enthalpies
• Isotopes
• Further information

Description

Magnesium is the eighth most abundant element in the earth's crust although not found in it's elemental form. It is a Group 2 element (Group IIA in older labelling schemes). Group 2 elements are called alkaline earth metals.

Magnesium is a grayish-white, 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. Normally magnesium is coated with a layer of oxide, MgO, that protects magnesium from air and water.

Magnesium is an important element for plant and animal life. Chlorophylls are porphyrins based upon magnesium. The adult human daily requirement of magnesium is about 0.3 g day^-1.

General information

Discoveror: Sir Humphrey Davy
Date discovered: 1755
Discovered at: England
Meaning of name: From the Greek word "Magnesia", a district of Thessaly

Physical data

Standard state: solid at 298 K
Colour: silvery white
Density of solid at ambient temperature/kg m^-3: 1738
Molar volume/cm³: 14.00

Radii /pm

Atomic: 145
Covalent (single bond):
Pauling radius for the ion [Mg]^-: no data

Valence shell orbital radius maxima (R_max)

orbital	s	p	d	f
radius	136.9	no data	no data	no data

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: 1.31
Allred Rochow: 1.23

Crystal Structure

structure: hcp (hexagonal close-packed)

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.

Temperatures (/K)

melting point: 923
boiling point: 1363

Enthalpies /kJ mol^-1

fusion: 8.48
vaporization: 128

single bond enthalpies:

Mg-F	Mg-Cl	Mg-Br	Mg-I	Mg-Mg
513	406	339	264	8.552

Ionization enthalpies /kJ mol^-1

Number	Enthalpy
1st	737.7
2nd	1450.7
3rd	7732.8
4th	10540
5th	13630
6th	17995
7th	21704
8th	25656

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass	Accurate mass	% natural abundance
24Mg	23.9850423 (8)	78.99 (3)
25Mg	24.9858374 (8)	10.00 (1)
26Mg	25.9825937 (8)	11.01 (2)

Further Information

• Additional information about WebElements 1.2.2
• This is a licensed copy (here is the full list) of WebElements 1.2.2 and contains a subset of the material contained within the main version of WebElements (version 2)
• For further information please try WebElements version 2
• Sheffield Chemdex: perhaps the largest internet chemistry directory
• Sheffield Chemputer: interactive chemistry calculators on the WWW