Question

Although Group 7A ions may have different oxidation states depending on which other elements are in the compound, the most common oxidation number for Group 7A (Group 17) ions is:

1−

3+

5+

7+

Answer 1

1-. Because Group 7A elements have 7 electrons in their valence shell, they need 1 more electron to complete the octet. Thus, it is generally true that all Group 7 electrons have an oxidation number of 1-. This also explains why electron affinity is largely the highest for Group 7A and lowest for Group 1A.