SolutionsProperties
1. Order by size
Arrange from smallest to largest:
- Li, Na, K
- C, N, O, F
- Li < Na < K: going down a group, the outer electrons are in shells further from the nucleus.
- F < O < N < C: across a period, the nucleus has more protons and attracts the electrons of the same shell more strongly.
2. Electronegativity
Arrange in order of increasing electronegativity: O, Li, F and C.
Li (1.0) < C (2.6) < O (3.4) < F (4.0). Electronegativity increases strongly across a period.
3. Sodium and neon
Why is the ionization potential of sodium much lower than that of neon, although it has only one more electron?
The electron that sodium loses is alone in shell 3, far from the nucleus and shielded by shells 1 and 2: it is easily removed, and sodium is left with the configuration of neon. Neon, instead, would have to lose an electron from a complete shell, much closer to the nucleus.