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Groups 1 and 2

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Anomalous Behaviour of Lithium and Beryllium

The very small size of the Li+ and Be2+ ions means that they have a large charge to size ratio and so show anomalous behaviour. The Li+ ion has a charge to size ratio comparable to that of Mg2+, and hence the properties of some lithium compounds resemble those of magnesium compounds.

Organometallic Compounds

The s-metals form a range of organometallic compounds which are used in inorganic and organic synthesis, mainly as sources of carbanions, ie. C– containers. In Group 1, organometallics have been made with all of the elements. The alkyllithium compounds are the most useful.

Complex Formation of the S-Metals

The s-metals have a strong affinity for hard F, O, and N ligands in solution, and they form strong complexes with them. This is especially true when the ligands are polydentate, that is they have more than one electron pair donor site. Examples are diphosphate, P2O74-, and EDTA4-, ethylenediaminetetraacetate. Monodentate ligands are only weakly bound due to the weak coulombic interactions and lack of covalent bond formation.

Solution Chemistry of the S-Metals

In solution, the metal ions are heavily hydrated. The primary hydration sphere is six water molecules (except Lithium which is four, due to its small size), but the ion-dipole coulombic interactions extend beyond the first sphere, ie. attraction between the ionic charge and the dipole on the water molecule.

Groups 1 and 2: The S-Metals

The s-metals consist of the Alkali Metals (Group 1) and the Alkaline Earth Metals (Group 2). They generally occur in compounds with oxidation states +1 and +2 respectively, though in the absence of air and water, some compounds with the metals in lower oxidation states may be prepared.