Chemistry · Ch 3 — Periodic Classification of Elements
Periodic Trends in Chemical Properties
3.6
Periodic Trends in Chemical Properties
The five properties studied so far -- atomic radius, ionic radius, ionisation enthalpy, electron gain enthalpy and electronegativity -- are all physical properties. Chemical properties such as reactivity, valence and oxidation state also show periodicity, though to a more limited extent. This section covers two such chemical patterns: the periodicity of valence (oxidation state) and the anomalous chemical behaviour of the second-period elem …
Table 3.16Variation of valence in groups
| Group 1 element | Valence-shell electrons | Valence | Group 15 element | Valence-shell electrons | Valence |
|---|---|---|---|---|---|
| Li | 1 | 1 | N | 5 | 3, 5 |
| Na | 1 | 1 | P | 5 | 3, 5 |
| K | 1 | 1 | As | 5 | 3, 5 |
| Rb | 1 | 1 | Sb | 5 | 3, 5 |
Table 3.17Variation of valence in period (2nd period)
| Element | Li | Be | B | C | N | O | F | Ne |
|---|---|---|---|---|---|---|---|---|
| Valence electrons | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |