9. Inorganic chemistry - 9.1 The periodic table: chemical periodicity


I Periodicity of physical properties of the elements: variation with proton number across the third period (sodium to argon) of:

II Periodicity of chemical properties of the elements in the third period

Learning outcomes

Candidates should, for the third period (sodium to argon), be able to:

(a) *describe qualitatively (and indicate the periodicity in) the variations in atomic radius, ionic radius, melting point and electrical conductivity of the elements (see the Data booklet)

(b) explain qualitatively the variation in atomic radius and ionic radius

(c) interpret the variation in melting point and in electrical conductivity in terms of the presence of simple molecular, giant molecular or metallic bonding in the elements

(d) explain the variation in first ionisation energy

(e) describe the reactions, if any, of the elements with oxygen (to give Na2O, MgO, Al 2O3, P4O10, SO2, SO3), chlorine (to give NaCl , MgCl 2, Al 2Cl 6, SiCl 4, PCl 5) and water (Na and Mg only)

(f) state and explain the variation in oxidation number of the oxides and chlorides

(g) describe the reactions of the oxides with water [treatment of peroxides and superoxides is not required]

(h) describe and explain the acid/base behaviour of oxides and hydroxides including, where relevant, amphoteric behaviour in reaction with sodium hydroxide (only) and acids

(i) describe and explain the reactions of the chlorides with water

(j) interpret the variations and trends in (f), (g), (h), and (i) in terms of bonding and electronegativity

(k) suggest the types of chemical bonding present in chlorides and oxides from observations of their chemical and physical properties

In addition, candidates should be able to:

(l) predict the characteristic properties of an element in a given group by using knowledge of chemical periodicity

(m) deduce the nature, possible position in the Periodic Table, and identity of unknown elements from given information about physical and chemical properties