1. Which of the following does NOT have an electron configuration ending with 3s2 3p6?

a) Cl- (chloride)

b) S2- (sulfide)

c) Al3+ (aluminum ion)

d) Ca2+ (calcium ion)

2. A complete electron configuration is given as: 1s2 2s2 2p6 3s2 3p6. What are 2 DIFFERENT (not the same element) atomic entities that could both have this configuration? Explain using complete sentences.

3. A complete electron configuration is given as: 1s2 2s2 2p5 3s1. Is this configuration possible? Explain using complete sentences AND an electron configuration diagram (upload image into answer).