Section 2 a) Specification

2.1 understand the terms group and period 

The period is the row that the element is in, it indicates how many shells of electrons it has.

The group is the column in which the element can be found. It indicates how many valence electrons the element has.

2.2 recall the positions of metals and non-metals in the Periodic Table 

The non-metals lie to the right of the red line, and metals to the left:

2.3 explain the classification of elements as metals or non-metals on the basis of their electrical conductivity and the acid-base character of their oxides 

Metals are characterised by their conductive abilities, and that their oxides dissolve in water to form bases.
Non-metals are insulators (except for carbon), and their oxides dissolve in water to form acids.

2.4 understand why elements in the same group of the Periodic Table have similar chemical properties 

Elements in the same group have the same number of valence electrons: they have to gain or lose the same number of electrons. This means their chemical properties are similar, but as the periods change the characteristic gradually changes. (e.g. reactivity increases, the colour gradually darkens, etc.)

2.5 understand that the noble gases (Group 0) are a family of inert gases and explain their lack of reactivity in terms of their electronic configurations.

Noble gases have full outer shells, so they are unreactive. Reactive elements are unstable, and react to achieve a full outer shell, but because noble gases have full outer shells, they don't have electrons to gain or lose.