I) Atomic radius increases down a group and decreases across a period. Element F is in Group 1, Period 3. Elements H and I are in Period 4. While elements in Period 4 are generally larger than those i

10. a)

i) Atomic radius increases down a group and decreases across a period. Element F is in Group 1, Period 3. Elements H and I are in Period 4. While elements in Period 4 are generally larger than those in Period 3, Group 1 elements have significantly larger atomic radii than elements in later groups, even if the latter are in a lower period. Comparing F (Group 1, Period 3) with H (Group 13, Period 4), F is larger.
The element with the largest atomic radius is F.

ii) Reactivity of non-metals increases across a period and decreases down a group. The most reactive non-metals are halogens (Group 17). Element K is in Group