Properties of the halogens

Melting and boiling points, X–X and H–X bond enthalpies, electron affinities, cycle-derived X⁻ hydration enthalpies, standard potentials and absorption maxima of F₂, Cl₂, Br₂ and I₂.


$\ce{F2}$	−219.6	−188.1	158.8	570.7	141.2	328.2	−523	2.866	285	—
$\ce{Cl2}$	−101.5	−34.0	242.6	431.6	198.8	348.6	−379	1.358	330	330
$\ce{Br2}$	−7.2	58.8	192.8	366.2	228.1	324.5	−348	1.066	415	415
$\ce{I2}$	113.7	184.4	151.1	298.3	266.6	295.2	−306	0.535	520	522

Bond enthalpies are dissociation enthalpies at 298 K; hydration enthalpies use the convention ΔhydH°(H⁺) = −1091 kJ/mol. The absorption peaks are literature maxima used to place the teaching bands behind the site’s computed colours, not measured spectra.

Sources

J. D. Cox, D. D. Wagman, V. A. Medvedev, CODATA Key Values for Thermodynamics (1989); D. D. Wagman et al., NBS tables (1982) (bond enthalpies from ΔfH° of X, X₂ and HX; X⁻(aq)).
NIST electron affinities (via the site’s Born–Haber data); K. P. Huber, G. Herzberg, Constants of Diatomic Molecules (1979) (bond lengths).
P. Vanýsek, “Electrochemical series”, CRC Handbook of Chemistry and Physics, 91st ed. (2010).
PubChem periodic table (melting and boiling points, via the site’s element table).

Used in these lessons

Halogens and noble gases