From The Student Room

TSR Wiki > Study Help > Subjects and Revision > Revision Notes > Chemistry > The Typical Characteristics of Transition Metals

---

Contents 1 High Melting Point and Boiling Point 2 High density 3 Form coloured compounds and ions in solution 4 Catalytic Properties 4.1 The metallic elements themselves 4.2 The compounds of transition metals 5 Comments

High Melting Point and Boiling Point

The bonding between the atoms in transition metals is very strong. The strong attractive force between the atoms is only weakened at high temperatures, hence the high melting points and boiling points.

For example: iron melts at 1535°C and boils at 2750°C BUT a Group 1 Alkali Metals such as sodium melts at 98°C and boils at 883°C.

High density

Another consequence of the strong bonding between the atoms in transition metals is they are tightly held together to give a high density.

For example: iron has a density of 7.9 g/cm³ and sodium has a density of 0.97 g/cm³ (and floats on water while fizzing! water has a density of 1.0 g/cm³).

Form coloured compounds and ions in solution

Transition metals tend to form more coloured compounds more than other elements either in solid form or dissolved in a solvent. The colours of some transition metal salts in aqueous solution are shown below:

Diagrams/pictures/colours missing.

1. Sc - scandium salts such as the chloride, ScCl₃, are colourless and not typical of transition metals
2. Ti - titanium(III) chloride, TiCl₃, is purple
3. V - vanadium(III) chloride, VCl₃, is green
4. Cr - chromium(III) sulphate, Cr₂(SO₄)₃, is dark green
5. Mn - potassium manganate(VII), KMnO₄, is purple
6. Fe - iron(III) chloride, FeCl₃, is yellow-orange-brown
7. Co - cobalt sulphate, CoSO₄, is pinkish
8. Ni - nickel chloride, NiCl₂, is green
9. Cu - copper(II) sulphate, CuSO₄, is deep blue
10. Zn - zinc salts such as zinc sulphate, ZnSO₄, are usually colourless and not typical of transition metals

Catalytic Properties

The metallic elements themselves

Many transition metals are used directly as catalysts in industrial chemical processes and in the anti-pollution catalytic converters in car exhausts.

For example iron is used in the Haber Synthesis of ammonia:

Nitrogen + Hydrogen Ammonia

or

via the Fe catalyst atoms

The compounds of transition metals

As well as the metals, the compounds of transition metals also acts as catalysts.

For example manganese dioxide (or manganese(IV) oxide), MnO₂, a black powder, readily decomposes an aqueous solution of hydrogen peroxide:

Hydrogen peroxide water + oxygen

or

via MnO₂ as the catalyst.

Comments