About The molecular world

From diamonds to dynamite everything involves a chemical reaction. This unit introduces you to the concepts and principles that underpin chemistry at the molecular level. Everyday experiences are used to help you to understand the more complex issues. After studying this unit you should be able to: explain what is meant by isotopes, atomic numbers and mass numbers of the atoms of chemical elements by referring to the Rutherford model of the atom; give an example of how differences in the molecular structures of chemical compounds give rise to differences in macroscopic properties; given a Periodic Table, point to some sets of elements with similar chemistry and to others in which there are progressive trends in chemical properties; indicate ways in which the chemical periodicity represented by a Periodic Table matches the periodicity in the electronic structure of atoms; use the Lewis structures of one or two simple chemical substances to illustrate the ideas of the octet rule, the electron-pair bond and the valence-shell repulsion theory of molecular shape; select a set of organic molecules, each of which contains the same functional group, and use its reactions to show why the functional group concept is useful; give an example of how the shape of a molecule can effect its rate of reaction; by referring to the three-way catalytic converter in a motor car, explain what is meant by a catalyst and distinguish the separate influences of the rate of reaction and the equilibrium contstant on the progress of a chemical reaction.