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Diatomic Molecules

Author: Hans Lohninger

Diatomic molecules are molecules composed only of two atoms (the Greek prefix "di-" means two). Seven of the chemical elements exists as diatomic molecules. Following is an alphabetical list of the most important diatomic molecules and the physical properties:

Compound Formula m.p. [C] b.p. [C] density
bromine Br2 -7.2 58.78 3.119 g/cm3
carbon monoxide CO -199 -191.5 1.250 g/l
chlorine Cl2 -100.98 -34.6 3.214 g/l
fluorine F2 -219.6 -188.14 1.69 g/l
hydrogen H2 -259.14 -252.87 0.0899 g/l
hydrogen bromide HBr -88.5 -67.0 3.5 g/l
hydrogen chloride HCl -114.8 -84.9 1.00045 g/l
hydrogen fluoride HF -83.1 19.54 0.991 g/l
iodine I2 113.5 184.35 4.93 g/cm3
lead oxide PbO 886 8.0 g/cm3
magnesium oxide MgO 2852 3600 3.580 g/cm3
nitrogen N2 -209.86 -195.8 1.2506 g/l
nitrogen monoxide NO -163.6 -151.8 1.3402 g/l
oxygen O2 -218.4 -182.96 1.429 g/l
zinc oxide ZnO 1975 5.606 g/cm3

Diatomic molecules consisting of the same atoms (e.g. H2 or Cl2) are called homonuclear molecules (in contrast to heteronuclear diatomic molecules, such as NO or CO). The bond in homonuclear diatomic molecules is covalent (non-polar).



Last Update: 2011-05-26