These substances have the bulk properties of Extended writing: explain covalent substances, only weak forces between molecular substances. why the melting point and their properties and the molecules boiling point increases as structure. (intermolecular forces). It the size of the molecule is these intermolecular does in terms of Practically test the forces that are overcome, intermolecular forces. conductivity of simple not the covalent bonds, covalent substances when the substance melts Extended writing: explain using ethanol and solid or boils. why covalent substances wax pieces. The intermolecular forces do not conduct electricity. increase with the size of the molecules, so larger Grade 9: explain why pure molecules have higher water does not conduct melting and boiling points. electricity but tap water These substances do not does conduct electricity. conduct electricity because the molecules do not have an overall electric charge. 4.2.2.5 Polymers have very large Students should be able 1 Extended writing: explain Model polymers. clips: molecules. The atoms in to recognise polymers how ethene polymerises. the polymer molecules are from diagrams showing Make a polymer from linked to other atoms by their bonding. cornstarch. strong covalent bonds. The intermolecular forces Investigate the YouTube: between polymer properties of plastic molecules are relatively bags. strong and so these substances are solids at room temperature. 4.2.2.6 Substances that consist of Students should be able 0.5 Extended writing: Research some uses of giant covalent structures to recognise giant describe the structure of covalent substances. are solids with very high covalent structures from diamond, silicon dioxide melting points. All of the diagrams showing their and graphite. Extension: make links atoms in these structures bonding and structure. between the uses of
These substances have only weak forces between the molecules (intermolecular forces). It is these intermolecular forces that are overcome, not the covalent bonds, when the substance melts or boils. The intermolecular forces increase with the size of the molecules, so larger molecules have higher melting and boiling points. These substances do not conduct electricity because the molecules do not have an overall electric charge. the bulk properties of molecular substances. Extended writing: explain why the melting point and boiling point increases as the size of the molecule does in terms of intermolecular forces. Extended writing: explain why covalent substances do not conduct electricity. Grade 9: explain why pure water does not conduct electricity but tap water does conduct electricity. covalent substances, their properties and structure. Practically test the conductivity of simple covalent substances using ethanol and solid wax pieces. 4.2.2.5 Polymers have very large molecules. The atoms in the polymer molecules are linked to other atoms by strong covalent bonds. The intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature. Students should be able to recognise polymers from diagrams showing their bonding. 1 Extended writing: explain how ethene polymerises. Model polymers. Make a polymer from cornstarch. Investigate the properties of plastic bags. clips: YouTube: 4.2.2.6 Substances that consist of giant covalent structures are solids with very high melting points. All of the atoms in these structures Students should be able to recognise giant covalent structures from diagrams showing their bonding and structure. 0.5 Extended writing: describe the structure of diamond, silicon dioxide and graphite. Research some uses of covalent substances. Extension: make links between the uses of
AQA-8462-SOW-BOND.DOCX