AS and A2 Chemistry notes and resources (WJEC specification) - UNIT CH2. Properties, Structure and Bonding

The uses to which materials can be put depend on their properties, which in turn depend on the bonding and structure within the material. By understanding the relationship between these factors, chemists are able to design new materials. The types of forces that can exist between particles are studied, along with several types of solid structures, in order to illustrate how these factors influence properties. The building blocks of materials are the elements and the relationship of their properties to their position in the Periodic Table is illustrated by a study of the elements of the s-block and Group 7. An introduction to organic chemistry provides the basis for an understanding of how the properties of carbon compounds can be modified by the introduction of functional groups.

4.2 - Forces between molecules

Candidates should be able to:

(a) explain the concept of a dipole and give a simple account of van der Waals' forces (dipole-dipole, induced dipole-induced dipole);

(b) explain the nature of hydrogen bonding and recall the types of elements with which it occurs e.g. with hydrogen attached to highly electronegative atoms;

(c) describe and explain the influence of hydrogen bonding on boiling points and solubility;

(d) appreciate that forces within molecules generally influence their chemical properties, whilst forces between molecules usually affect their physical properties;

(e) appreciate the relative orders of magnitude of the strength of covalent bonds, hydrogen bonds and van der Waals' forces. GCE AS and A CHEMISTRY 19