[SOS]

It says I have to give an explanation why this happens, but I don't know if my answers are correct? If not, can someone explain this to me?

a) The electron affinity for P is lower than the electron affinity for Si.

I don't know what the exception is? I need an explanation..

and

b) Element Q has the following three ionization energies (kJ/mol) shown below. Based on this data, what group does element Q belong to?Explain your reasoning.

Ionization 1 = 496
Ionization 2 = 4568
Ionization 3 = 6920

I know the answer for this is in the Alkali metal but I'm not sure why. Can someone explain how to figure this one out for me?

[Fluorine]

b) Element Q has the following three ionization energies (kJ/mol) shown below. Based on this data, what group does element Q belong to?Explain your reasoning.

Ionization 1 = 496
Ionization 2 = 4568
Ionization 3 = 6920

I know the answer for this is in the Alkali metal but I'm not sure why. Can someone explain how to figure this one out for me?

When a alkali loses an electron what does it become isoelectronic with? Take sodium for example and look at the periodic table. When it loses an electron what does it's electron configuration mimic? Does this element have a high ionization energy - why?

You should be able to solve part b if you can answer these.

Edit: I changed lithium to sodium.

[SOS]

b) Element Q has the following three ionization energies (kJ/mol) shown below. Based on this data, what group does element Q belong to?Explain your reasoning.

Ionization 1 = 496
Ionization 2 = 4568
Ionization 3 = 6920

I know the answer for this is in the Alkali metal but I'm not sure why. Can someone explain how to figure this one out for me?

When a alkali loses an electron what does it become isoelectronic with? Take sodium for example and look at the periodic table. When it loses an electron what does it's electron configuration mimic? Does this element have a high ionization energy - why?

You should be able to solve part b if you can answer these.

Edit: I changed lithium to sodium.

Ground state Na has 11 electrons and it's configuration is: 1s²2s²2p⁶3s¹

and when it loses an electron it's config is 1s²2s²2p⁶ making it have only 10 electrons. Which is similar to Neon that is stable. And since Neon is stable (has an octet) it takes a lot of energy to remove an electron. Just like Na, now a stable form that has gotten rid of all it's valence e-. And so thats why the ionization energy jumped that much. Am I correct?

[Fluorine]

Yes excellent, that's is why the ionization energy jumped so much. The neon isoelectronic configuration is a "comfortable" state for sodium, which will ionize at first readily, then take a lot (neon config.), and the third ionization already has a 2+ charge preventing.