The
properties of the
d-block elements in the same row are generally
similar to one another and intermediate between the same properties of the
s-block and
p-block elements.
Examples of this are first ionisation energy, atomic radius and electronegativity. The graphs show that the change in these properties is more gradual from element to element across
d-block than for
s-block or
p-block.
TransitionMetalElectronegativity
The
similarity in these properties as well as the tendency for transition metals to form ions in
multiple oxidation states (M
2+ and M
3+ for example) can be rationalised on the basis of
electron configuration.
All elements in the first transition series have valence electrons in both 4s and 3d orbitals. Each successive element has an additional electron in the 3d subshell.
Orbital energies depend on the number of electrons occupying them. 4s and 3d orbitals have very similar energies. For atoms having the number of electrons in the first row d-block elements, 3d orbitals are of lower energy than the 4s orbitals.
The
relatively gradual decrease in atomic radius can be attributed to the electron added to the inner shell (3
d) more effectively shielding outer shell electrons (in 4
s) on atoms of the elements from the pull of the nucleus.
TransitionMetalAtomicRadii
This contrasts with
s-block or
p-block elements where the additional electron is not as effective a shield from the nucleus because it is added in the same shell as the outer electrons.
s indicate relative
orbital energies.
Electrons in
higher energy orbitals have
lower ionisation energies because they are less attracted to the nucleus.
The
lack of an abrupt change in first ionisation energy from calcium to the transition series is consistent with the highest energy (outermost) electron for
d-block metals being in a 4
s orbital as for calcium.
The
gradual increase in ionisation energy across
d-block can be ascribed to the attractive forces due to the higher nuclear charge more than off-setting the increased repulsive forces due to the additional electron.
Row 4 elements all first IE
The focus of this activity is to demonstrate, through ionisation energy data, more detail about how electron configurations and orbital energies are consistent with both the similarities and the differences between the chemistry of the
d-block metals.