2
Trends in enthalpies
of atomisation of
transition elements
In general, ions of the same charge in a given series show progressive
decrease in radius with increasing atomic number This is because the
new electron enters a d orbital each time the nuclear charge increases
by unity It may be recalled that the shielding effect of a d electron is
not that effective, hence the net electrostatic attraction between the
nuclear charge and the outermost electron increases and the ionic
radius decreases The same trend is observed in the atomic radii of a
given series