Final answer:
Transition metals typically have two valence electrons, with some exceptions having one. They exhibit multiple oxidation states, which is a characteristic feature of their chemistry. Groups 3-12 transition metals do not conform to the typical rule for determining valence electrons by the group number.
Step-by-step explanation:
Determining the number of valence electrons in transition metals can be more complex than for other elements. In typical representative elements, the group number on the Periodic Table provides a clear indication of the number of valence electrons.
For example, alkali metals in Group 1 have one valence electron, whereas alkaline earth metals in Group 2 have two. However, transition metals in Groups 3-12 do not follow this straightforward rule.
Transition metals commonly have two valence electrons, as the 4s orbital is filled before the 3d orbital begins to fill. However, some transition metals with unusual electron configurations may only have one valence electron.
Additionally, they exhibit multiple oxidation states due to the relative ease of losing electrons from the d-orbital after the s-orbital electrons have been removed. This ability to display a variety of oxidation states is a key characteristic of transition metal chemistry.
Examples of the variable oxidation states among transition metals include Scandium (+3), Titanium (+3 and +4), Vanadium (+2 to +5), Chromium (+2, +3, +4, +6), Manganese (+2, +3, +4, +6, +7), Iron (+2, +3, +6), Cobalt and Nickel (+2 and +3), Copper (+1, +2, and +3), and Zinc, which notably only has a +2 oxidation state.