Transition Elements

Definition of Transition Elements

Electronic Configurations

Zinc and Scandium

Working out electronic configurations

Questions

These are metals, they live in the d-block of the periodic table, between the s and p blocks. You only need to know about the first row of the transition metals scandium to zinc (Sc → Zn).

OCR specify that the following points are essential:

• Definition

• Electronic configuration (elements and ions)

• Catalytic behaviour

• Oxidation states

• Hydroxides

• Colour

• Complex ions

• Working out the formula of a complex ion – colorimetry

• Redox reactions and titration calculations

Definition of d-block (transition elements)

This needs to be learnt – reproducible at will!

Electronic configuration

This is quite easy – as usual in chemistry there is a pattern, BUT in this case the configuration of chromium and copper are different.

Notice that Cr and Cu do not fit the pattern. A half-filled or completely filled sub-shell is more stable energetically, so Cr and Cu adopt this pattern.

Zinc and Scandium?

Although these are in the d-block, they are not transition elements. They have no ion that has a partially filled d orbital.

Zinc

• Forms only one ion (other transition elements form 2 or more).
• Zn²⁺ has a completely full 3d sub-shell.
• Zn²⁺ has the following configuration 1s² 2s² 3s² 3p⁶ 3d¹⁰.

Scandium

• Forms only one ion (other transition elements form 2 or more).
• Sc³⁺ has no 3d or 4s electrons.
• Sc³⁺ has electronic configuration 1s² 2s² 3s² 3p⁶.

Remember in making the ions of transition elements, the 4s electrons are removed first!

Working out electronic configurations

Work out the electronic configuration of Fe²⁺.

Write out the configuration of the ion [Ar] 3d⁶ 4s²

·        Remove the number of electrons – remembering that the 4s go first.

So the electronic configuration of Fe²⁺ is [Ar] 3d⁶.

Now try the questions