4.2+Covalent+bonding

Learning Goals: (6 hours)
 * Describe the covalent bond as the electrostatic attraction between a pair of electrons and positively charged nuclei.
 * Describe how the covalent bond is formed as a result of electron sharing.
 * Deduce the Lewis (electron dot) structures of molecules and ions for up to four electron pairs on each atom.
 * State and explain the relationship between the number of bonds, bond length and bond strength.
 * Predict whether a compound of two elements would be covalent from the position of the elements in the periodic table or from their electronegativity values.
 * Predict the relative polarity of bonds from electronegativity values
 * Predict the shape and bond angles for species with four, three and two negative charge centres on the central atom using the valence shell electron pair repulsion theory (VSEPR).
 * Predict whether or not a molecule is polar from its molecular shape and bond polarities.
 * Describe and compare the structure and bonding in the three allotropes of carbon (diamond, graphite and C60 fullerene).
 * Describe the structure of and bonding in silicon and silicon dioxide.