IB syllabus > periodicity > 3.2 

These notes were written for the old IB syllabus (2009). The new IB syllabus for first examinations 2016 can be accessed by clicking the link below.

IB syllabus for first examinations 2016

3.2 - Physical properties

3.2.1 - Describe and explain the periodic trends in atomic radii, ionic radii, ionization energies, electronegativity and melting points for the alkali metals (Li to Cs), halogens (F to I) and period 3 elements (Na to Ar).

Cross reference with topics 2, 4 and 5. Data for all these properties are listed in the data booklet. Explanations for the first four trends should be given in terms of the balance between the attraction of the nucleus for the electrons and the repulsion between electrons. Explanations based on effective nuclear charge are not required. Ionization energy is defined as the minimum energy required to remove one electron from an isolated gaseous atom.