Quantum behaviour

Abstract

The identity and size of atoms is explicable only in quantum physics. The double slit experiment illustrates the wave-particle duality of light and of matter. To describe quantum interference the concept of a complex probability is introduced, the squared amplitude of which is the probability of a particle being at a particular location. The uncertainty relation requires atomic motion in solids even at absolute zero. The symmetry of exchanging indistinguishable particles leads to the classification of particles as fermions or bosons. The exclusion principle applies to electrons and rationalises the Periodic Table and much more. Electrons in solids exist in bands of energy. Band theory explains why some materials are electrical conductors, others are insulators or semiconductors. Chemical bonding involves quantum tunnelling of electrons. Hydrogen may diffuse in solids by quantum tunnelling. The temperature dependence of the specific heat of a solid is explicable only in quantum physics.