| 1.4: THE PERIODIC TABLE |
|---|
The Periodic Table arranges elements in order of increasing atomic number, with vertical groups and horizontal periods providing a logical structure.
The period number equals the number of occupied electron shells, and the group number equals the number of outermost electrons for main group elements (Groups 1–7).
This direct link between electronic configuration and position means that an element's chemical behaviour can be predicted from where it sits in the Table.
Elements in the same group share similar chemical properties because they have the same number of outer electrons, and these outer electrons determine how atoms bond and react.
Metals
- Are found on the left and centre of the Table
- Conduct electricity well
- Form basic oxides that react with acids
Non-metals
- Are found on the right of the Table
- Are poor conductors of electricity
- Form acidic oxides
These two properties — electrical conductivity and oxide character — provide experimental methods to classify any element.
Noble gases
- Are placed in Group 0
- Are uniquely unreactive because they already possess full outer electron shells, giving them no chemical drive to gain, lose, or share electrons
At a Glance
| Element Type | Position in the Table | Electrical Conductivity | Oxide Character | Reactivity |
|---|---|---|---|---|
| Metals | Left and centre of the Table | Conduct electricity well | Form basic oxides that react with acids | Varies — Group 1 and 2 metals are very reactive; transition metals are much less reactive |
| Non-metals | On the right of the Table | Poor conductors | Form acidic oxides | Varies — Group 7 (halogens) are reactive; others less so |
| Noble gases | Group 0 | Poor conductors | Do not normally form oxides (unreactive) | Uniquely unreactive because they already possess full outer electron shells |
Understanding these patterns transforms the Periodic Table from a reference chart into a powerful predictive tool for chemistry.