1. The covalent compound ethanol melts at –114 8C. Is it a molecular compound, or a giant structure? Explain.
2. Diamond and graphite are allotropes of carbon. What does
that mean?
3 Why is diamond so hard?
4 Why do diamond and graphite have such very different
properties? Draw diagrams to help you explain.
5 a Explain why silica has a high melting point.
b See if you can suggest a reason why its melting point is
lower than diamond’s.