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. Organolithium compounds These are found in ether or hydrocarbon solutions, and are formed from the reaction of the metal and the … Read more
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 … Read more
Aqueous solution chemistry 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. The enthalpy of hydration increases as z2/r, therefore the enthalpy of … Read more
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. Some of the Group 1 and 2 metals are amongst the most abundant: … Read more
Compounds formed with bonds between different Halogen atoms are known as interhalogen compounds. The binary compounds have formulae XY, XY3, XY5 and XY7 (where X is the heavier halogen atom). Ternary species are also formed, and the species can be neutral, cations or anions. All the interhalogens are thermodynamically stable with respect to decomposition to the elements, though the low … Read more
The reactions of the halogen oxoanions have a strong dependence on the conditions. The oxidizing power is greatly altered by pH: in acidic solution, the standard reduction potential for the perchlorate ion ClO4– is +1.20 V, whereas in basic solution it is +0.37 V. Acidic solution, pH = 0 Basic solution, pH = 14 Another important aspect of the redox chemistry … Read more
Fluorine, the lightest of the halogens, has several unique features to its chemistry which merit individual discussion: The bond strength of the F2 molecule is unexpectedly low when compared to the other dihalogens. This is due to the repulsion between the lone pairs on the fluorine atoms (non-bonding pair repulsion) which becomes important when they are so close … Read more
The halogens form a range of compounds with oxygen, but many of these are unstable. Oxides are formed in the range E2O to E2O7. Oxoacids are formed in the range HOE to HOEO3 (there is only HOF with fluorine). Oxoanions are formed in the range EO– to EO4–. Halogen oxides Fluorine forms two compounds with oxygen. Oxygen difluoride, OF2, … Read more
The halogens have electronic configuration [NG]ns2np5 (where NG implies the relevant Noble Gas), and the accessible oxidation states range from -1 to +7. The stability of the highest oxidation state increases down the group: Fluorine only occurs in the -1 and 0 oxidation states, because it is the most electronegative element and so is never found in a positive … Read more
Sulphur and phosphorus bear similar relationships to nitrogen and oxygen. The principal differences between S/P and O/N are as follows. Oxidation states, coordination numbers and stereochemistries Valence shell expansion, and the resultant formation of species like PX5, PX6–, R3P=CR2, and SF6, SF5Cl, SF4 have no N or O counterparts, the highest coordination being NX3 and OX2. This is due … Read more