Cambridge O Level Chemistry · Syllabus 5070 · Atoms, Elements and Compounds
Giant covalent structure
What is Giant covalent structure?
A structure in which a very large number of atoms are joined by strong covalent bonds into one continuous network, rather than into separate small molecules. Melting such a substance requires many strong covalent bonds to be broken, so giant covalent substances have very high melting points and are usually hard. Diamond, graphite and silicon(IV) oxide are the three examples required at this level.
This definition is part of the Atoms, Elements and Compounds chapter in Cambridge O Level Chemistry.
Giant covalent structure in context
An atom is the smallest particle of an element, made of a central nucleus containing protons and neutrons surrounded by electrons arranged in shells. Chapter 2 of Cambridge O Level Chemistry 5070 builds everything on this structure: the proton number fixes which element an atom is, the electronic configuration (for example 2,8,3) fixes how its outer electrons behave, and what those outer electrons do — transfer, share or delocalise — decides whether a substance forms a giant ionic lattice, simple molecules, a giant covalent structure or a giant metallic lattice. Each structure in turn explains the melting point, the electrical conductivity and the uses of the substance.