Below table shows the general trend in periodicity in properties of oxides, hydroxides, oxy-acids and hydrides of compounds of elements across a period and down a group:
| Across a period | Down a group | |
|---|---|---|
| Oxides | Varies from strongly basic to strongly acidic | Varies from acidic to basic |
| Hydroxides | Varies from strongly basic to amphoteric | Varies from less basic to strongly basic |
| Oxy-acids | Varies from weak oxy-acids to strong oxy-acids | Varies from strong oxy-acids to weak oxy-acids |
| Hydrides | Varies from strongly basic to strongly acidic | Varies from less acidic to more acidic |