Inorganic

The building up principle gives the ground state electronic configurations of the elements, and there are similarities running through those configurations. The elements can be arranged into groups which all have the same generic electronic configuration, specifically the structure of the valence shell outside a noble gas core. These groups form the periodic table: The Periodic Table 1 … Read more

Zeolites are a class of aluminosilicates which have rigid anionic frameworks containing well defined channels and cavities. These cavities contain metal cations, such as Na+ and K+, which are exchangeable, and also neutral guest molecules, such as water, which can be removed and replaced. The general formula for a zeolite is Mx/n[(AlO2)x(SiO2)y].mH2O, where n is the valency of the metal ion M which balance the negative … Read more

Ion transport is measured in terms of the ionic diffusion coefficients. In general, the diffusion in solids is much slower than in liquids and gases, but there are important exceptions, when certain compounds can have very high ionic diffusion coefficients. This has a large effect on the conductivity of those compounds. Diffusion is an activated process, governed … Read more

All solids contain defects, where the ideal lattice as described in terms of an infinitely repeating unit cell is broken. Defects can have a large effect on a range of properties of the material, such as the mechanical strength, electrical conductivity, corrosion and chemical reactivity. Defects may be formed due to thermodynamic effects, and these defects are known as intrinsic defects, … Read more

When metals and semiconductors conduct, the motion of the electrons has to overcome the vibrational motion of the atoms in the crystal lattice. This lattice vibration, or phonon, leads to scattering of the electrons, or electrical resistance. A superconductor is a substance which conducts electricity without resistance. A superconductor exhibits zero electrical resistance because the electrons near the Fermi level interact attractively … Read more

Semiconductors are those compounds with small band gaps between fully filled and fully unoccupied bands. Let us consider the elements of Group 14. These all adopt the structure of diamond, in which the atoms are all tetrahedrally coordinated by other atoms. Band Structure in Body Centered Cubic crystal Band Structure in tetrahedral diamond crystal If the Group 14 elements … Read more

The size of the band gap varies with the type of compound involved. The Band Gap in Ionic Solids The dominant term in determining the band gap is the Madelung energy. Band gap in Sodium Chloride Na+Cl– is unstable with respect to Na-Cl at infinite r, but is stabilised by the Madelung potential at small r (or large 1/r). At the separation when the … Read more

The electrons in molecules are described in terms of molecular orbital theory. In this the electrons occupy a set of molecular orbitals which belong to a corresponding set of molecular energy levels. These molecular orbitals are made up of linear combinations of atomic orbitals, adapted for the symmetry of the molecule. Often, a given molecular orbital will have the character, … Read more

A Frost Diagram is another way of displaying the reduction potentials for the various oxidation states of a given element, X. It shows nE against the oxidation number N: here, E is the reduction potential for the X(N)/X(0) couple, and n is the number of electrons transferred in the conversion of X(N) to X(0). The Frost Diagram for NitrogenThe thick black line is for acidic … Read more