Final Answer:
1. Atomic radius increases as you go down a group.
2. More electron shells are added, making the atom larger.
3. Atomic radius decreases as you go across a period.
4. More protons pull electrons closer, shrinking the atom.
5. a) Al b) S c) Br d) Na e) O f) Ca
6. C < O < Sn < Sr — O and C are small (same period, O smaller); Sn and Sr are large (lower periods), Sr is largest (farther down).
7. Electronegativity is how strongly an atom pulls shared electrons in a bond.
8. Nonmetal ionic radius is larger than its atomic radius (gains electrons).
9. Electronegativity decreases down a group.
10. Atoms get bigger, so nucleus pulls less on bonding electrons.
11. Electronegativity increases across a period.
12. More protons pull electrons tighter, increasing pull strength.
13. a) Ga b) O c) Cl d) Br e) Sr f) O
14. Group 1 (alkali metals)
15. Group 2 (alkaline earth metals)
16. Group 17 (halogens)
17. Group 18 (noble gases)
Parent Tip: Review the logic above to help your child master the concept of periodic trends worksheet.
