Answer:
1- Se 2-Na 3- I guess Si as well 4-Ar 5-O
Explanation:
- Ionization energy increases as we go right in period
- Ionization energy increases as we go upwards in groups
- Atomic radius increases as we go downwards in groups
- Atomic radius increases as we go left in periods
- Atomic radius decreases as we go right in periods so when atoms loses electron or more the smaller its radius becomes
