Final answer:
True. Elements in the s- or p-blocks generally have only one common oxidation number, while d-block elements can have more than one possible oxidation number.
Step-by-step explanation:
True. Elements in the s- or p-blocks generally have only one common oxidation number, while d-block elements can have more than one possible oxidation number. The s-block elements, which include Group 1 (also known as Group 1A) and Group 2 (also known as Group 2A) elements, typically have only one common oxidation number. For example, Group 1 elements such as sodium (Na) and potassium (K) always have an oxidation number of +1. Group 2 elements such as magnesium (Mg) and calcium (Ca) always have an oxidation number of +2.
In contrast, elements in the d-block (also known as the transition metals) can have multiple oxidation numbers due to the variable filling of their d orbitals. Transition metals often form cations with different ionic charges. For example, iron (Fe) can form the Fe²+ ion by losing two electrons, or the Fe³+ ion by losing three electrons.