The d Block

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Electrons from both inner d sub-shell and outer s sub-shell can be involved in compound formation

Slide 11

What is a transition metal?

Not all d block elements have incomplete d sub-shells

e.g. Zn has e.c. of [Ar]3d104s2, the Zn2+ ion ([Ar] 3d10) is not a typical TM ion

Similarly Sc forms Sc3+ which has the stable e.c of Ar. Sc3+ has no 3d electrons

Slide 12

What is a transition metal?

For this reason, a transition metal is defined as being an element which forms at least one ion with a partially filled sub-shell of d electrons.

In period 4 only Ti-Cu are TM’s!

Note that when d block elements form ions the s electrons are lost first

Slide 13

What are TM’s like?

TM’s are metals

They are similar to each other but different from s block metals eg Na and Mg

Properties of TM’s

Dense metals

Have high Tm and Tb

Tend to be hard and durable

Have high tensile strength

Have good mechanical properties

Slide 14

What are TM’s like?

Properties derive from strong metallic bonding

TM’s can release e- into the pool of mobile electrons from both outer and inner shells

Strong metallic bonds formed between the mobile pool and the +ve metal ions

Enables widespread use of TMs!

Alloys very important: inhibits slip in crystal lattice usually results in increased hardness and reduced malleability

Slide 15

Effect of Alloying on TM’s

Slide 16

TM Chemical Properties

Typical chemical properties of the TM’s are

Formation of compounds in a variety of oxidation states

Catalytic activity of the elements and their compounds

Strong tendency to form complexes

See CI 11.6

Formation of coloured compounds

See CI 11.6

Slide 17

Variable Oxidation States

TM’s show a great variety of oxidation states cf s block metals

If compare successive ionisation enthalpies (Hi) for Ca and V as follows

M(g)  M+(g) + e- Hi(1)

M+(g)  M2+(g) + e- Hi(2)

M2+(g)  M3+(g) + e- Hi(3)

M3+(g)  M4+(g) + e- Hi(4)

Slide 18

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Hi for Ca and V

Slide 19