The statement "covalently bonded substances always consist of small molecules" is false. Covalent bonding involves the sharing of electron pairs between atoms, which can form molecules of various sizes and structures. Some covalently bonded substances consist of small molecules, such as water (H2O) or methane (CH4), held together by weak intermolecular forces. However, many covalently bonded substances form giant covalent (or macromolecular) structures, which are extensive networks of atoms interconnected by covalent bonds, such as diamond or silicon dioxide. These giant covalent structures do not consist of small molecules but rather huge lattices with high melting points due to the strong covalent bonds throughout the structure. Thus, covalent substances can be either simple small molecules or large giant covalent networks, not always small molecules.