Students should be able to:
(a) understand the nature of ionic, covalent and dative
covalent bonds, and the simple charge cloud representation of s and p bonds
(b) understand the intermediate nature of most bonds in terms of:
(i) electronegativity difference leading to polarity in bonds
(ii) polarising power of cations and polarisability of anions and
the factors affecting these.
(c) understand that polar bonds may or may not give rise to
permanent dipoles within molecules
(d) understand the nature of intermolecular forces, resulting
from interactions between permanent dipoles and induced dipoles,
and from the formation of hydrogen bonds
(e) show how these various types of bond give rise to giant
atomic structures (eg diamond and graphite), hydrogen-bonded
molecular structures (eg ice), ionic structures (eg sodium
chloride), simple molecular structures (eg iodine) and polymers
(eg poly(ethene), and how The properties of solids are related to
the structure and bonding.
• students will only be required to draw simple
representations of the diamond andgraphite structure(s), sodium
chloride and ice
• the properties required will be melting temperature,
density and electrical conductivity
(f) understand the existence of interparticle forces in the
liquid state and hence explain the trends in the boiling
temperatures of the noble gases, and in the boiling temperatures
of the hydrides of the elements of Groups 4, 5, 6 and 7
(g) interpret changes of state in terms of the types, motion and
arrangement of particles present (atoms, molecules or ions) and
explain associated energy changes
(h) recall the shapes of the following molecules and ions:
BeCl2, BCl3, CH4, HCl, NH3,
NH4 + , H2O, CO2, SO2,
SO3 2- , CO3 2-, NO3 - , PCl5, SF6
(i) interpret these shapes in (h) in terms of the Valence Shell
Electron Pair Repulsion Theory, and predict the shapes of related
molecules and ions (eg from a knowledge of NH3 the
shape of PH3 can be predicted by analogy)
(j) describe metallic bonding and explain the electrical
conductivity of metals and of graphite in terms of the mobility
of electrons.
• details of types of metallic structures will not
be examined.
• questions on transition metals will not be
asked in this unit.