18.5 Summarry on the main group elements *18.5.1 The general properties of the s-block elements 18.5.2 Outline on the p-block elements 18.5.3 The property variations for compounds of p-block elements§ 18.5 Summarry on the main group elements *18.5.1 The general properties of the s-block elements 18.5.2 Outline on the p-block elements 18.5.3 The property variations for compounds of p-block elements