Transition Metals - Characteristics of Transition Metals (A-Level Chemistry)
Properties of Transition Metals
Physical Properties
- Transition metals have higher melting and boiling points than Group 1 and 2 metals. This is because, as 3d electrons can also become delocalised, the number of electrons involved in the metallic bonding increases. Therefore metallic bonding in transition metals is stronger than in Group 1 or 2 metals.
- Transition metals have higher densities than Group 1 and 2 metals. The same reason applies as for melting points. The increased number of delocalised electrons, increases the strength of the electrostatic forces holding the metallic lattice together so that the positive metal ions are more closely packed together and the density of the metal increase.
- Transition metals are worse electrical conductors than Group 1 and 2 metals. The only exception is copper metal.
- Atomic radii of the transition metals in the same period are all fairly the same. This is because as we move along the period, electrons are added to the same 3d sub-level, instead of to a higher sub-level.
- First ionisation energies of the transition metals in the same period are all fairly the same. As we move along the period and protons get added to the nucleus, nuclear charge increases so that the attraction between outermost electrons and the nucleus increases. However, as electrons get added to the same 3d sub-level, the level of shielding experienced by the outermost electrons stays fairly the same. Therefore, the amount of energy required to remove them does not change much.
Characteristic Properties of Transition Metals
- Transition metals have variable oxidation states. As we saw in the previous chapter, the fact that transition metal atoms can lose electrons from both the 4s and the 3d sub-levels, means that they can form ions with different oxidation states.
- Transition metals make good catalysts. A catalyst is a substance that speeds up the rate of a reaction by providing an alternative reaction pathway with a lower activation energy. We will look at the catalytic activity of transition metals in more detail in future chapters.
- Transition metals form coloured compounds. This is because transition metals can form coloured ions. We will look at this in more detail in future chapters.
- Transition metals can form complex ions. Complex ions are made up of more than one atom. We will look at complex ions in more detail in future chapters.
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