Atomic and ionic radii
A halogen atom has the smallest radius as compared to any other element in its period. This is due to the increased effective nuclear charge which results in greater attraction of the electrons by the nucleus. The atomic radii. Increase from fluorine to iodine down the group due to increase in number of shells.
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Covalent radius (pm) |
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Ionic radius (pm) |
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(2) Ionization energy : Ionization energy of these elements are higher than those of the corresponding elements of group 16 due to increased nuclear charge. these values decrease systematically as we move down the group from F to 1
Thus iodine which has a comparatively low value of I.E., has a tendency to lose an electon to form positive iodinium ion, I+ and thus shown electropositive or metallic character.
(3) Electronegativity : Fluorine is the most electronegative element in the periodic table. With increase in atomic number down the group, the electronegativity decreases.
The decreasing order of electronegativity is F > Cl > Br > I.
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