8. challenge question: which ion is larger, fe2+ or fe3+? explain.

Explanation:

Step1: Consider electron - proton ratio

Both Fe²⁺ and Fe³⁺ have the same number of protons (26 for iron). Fe²⁺ has 24 electrons and Fe³⁺ has 23 electrons.

Step2: Analyze electrostatic attraction

With the same nuclear charge (number of protons), the ion with more electrons has a lower effective nuclear charge per electron. The greater number of electrons in Fe²⁺ means the electrons are less tightly held compared to Fe³⁺. So, Fe²⁺ has a larger ionic radius.

Answer:

Fe²⁺ is larger. The reason is that both ions have the same number of protons, but Fe²⁺ has one more electron than Fe³⁺, resulting in a lower effective nuclear - charge per electron and a larger ionic radius.