Topic Periodicity (6 hours) - 3.2 Periodic trends

Nature of science:

Looking for patterns-the position of an element in the periodic table allows scientists to make accurate predictions of its physical and chemical properties. This gives scientists the ability to synthesize new substances based on the expected reactivity of elements. 3.1


Vertical and horizontal trends in the periodic table exist for atomic radius, ionic radius, ionization energy, electron affinity and electronegativity.

Trends in metallic and non-metallic behaviour are due to the trends above.

Oxides change from basic through amphoteric to acidic across a period.

Applications and skills

Prediction and explanation of the metallic and non-metallic behaviour of an element based on its position in the periodic table.

Discussion of the similarities and differences in the properties of elements in the same group, with reference to alkali metals (group 1) and halogens (group 17).

Construction of equations to explain the pH changes for reactions of Na2O, MgO, P4O10, and the oxides of nitrogen and sulfur with water.


Only examples of general trends across periods and down groups are required.For ionization energy the discontinuities in the increase across a period should be covered.

Group trends should include the treatment of the reactions of alkali metals with water, alkali metals with halogens and halogens with halide ions