1 The structure of the periodic table

Elements are arranged in increasing atomic number in the periodic table Elements in Groups have similar physical and chemical properties The atoms of elements in a group have similar outer shell electron configurations, resulting in similar chemical properties; Elements in periods showing repeating trends in physical and chemical properties Period 2 = Li, Be, B, C, N, O, F, Ne Period 3 = Na, Mg, Al, Si, S, Cl, Ar. Classification of elements in s, p, d blocks Elements are classified as s, p or d block, according to which orbitals the highest energy electrons are in. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 Na Mg Al Si P S Cl Ar atomic radius (nm) Atomic radius Atomic radii decrease as you move from left to right across a period, because the increased number of protons create more positive charge attraction for electrons which are in the same shell similar shieding. Exactly the same trend in period 2 N Goalby chemrevise.org Periodicity is a repeating pattern across different periods Various properties such as atomic radius, melting points, boiling points and ionisation energy display periodicity