1) How are covalent bonds formed? a) By atoms sharing protons. b) By atoms sharing neutrons. c) By atoms sharing shells. d) By atoms sharing electrons. 2) Which type of atoms form covalent bonds between them? a) Non-metals. b) Metals. c) Metals and non-metals. d) Composites. 3) Describe the structure and bonding of a giant covalent substance. a) Billions of atoms bonded together by weak covalent bonds. b) Billions of atoms bonded together by electrostatic covalent bonds. c) Billions of atoms bonded together by strong covalent bonds. d) Billions of atoms bonded together by double covalent bonds. 4) Describe the structure and bonding of small molecules. a) Large numbers of atoms group together into molecules with weak covalent bonds between the atoms and weak intermolecular forces between the molecules. b) Small numbers of atoms group together into molecules with strong covalent bonds between the atoms and weak intermolecular forces between the molecules. c) Great numbers of atoms group together into molecules with strong ionic bonds between the atoms and weak intermolecular forces between the molecules. d) Small numbers of atoms group together into molecules with strong ionic bonds between the atoms and weak intermolec 5) Describe the structure and bonding of polymers. a) Many different molecules joined together by strong covalent bonds in a long chain, with weak intermolecular forces between the chains. b) Many identical molecules joined together by weak covalent bonds in a short chain, with strong intermolecular forces between the chains. c) Many identical molecules joined together by weak ionic bonds in a long chain, with weak intermolecular forces between the chains. d) Many identical molecules joined together by strong covalent bonds in a long chain, with weak intermolecular forces between the chains. 6) Why do giant covalent substances have high melting points? a) It takes a lot of energy to break the strong covalent bonds between the atoms. b) It takes a lot of energy to break the weak covalent bonds between the atoms. c) It takes a lot of energy to break the strong ionic bonds between the atoms. d) It takes a lot of energy to break the weak ionic bonds between the atoms. 7) Why do small molecules have low melting points? a) A large amount of energy is needed to break the strong intermolecular forces. b) Only a small amount of energy is needed to break the strong intermolecular forces. c) Only a small amount of energy is needed to break the weak intermolecular forces. d) Only a small amount of energy is needed to break the weak electrostatic forces. 8) Why do large molecules have higher melting and boiling points than small molecules? a) The intermolecular forces are stronger in large molecules. b) The intermolecular forces are weaker in large molecules. c) The electrostatic forces are stronger in large molecules. d) The electrostatic forces are weaker in large molecules. 9) Why do most covalent substances not conduct electricity? a) Do not have localised electrons or ions. b) Do not have delocalised protons or ions. c) Do not have delocalised electrons or atoms. d) Do not have delocalised electrons or ions. 10) Describe the structure and bonding in graphite. a) Each carbon atom is bonded to three others in hexagonal rings arranged in layers - it has delocalised electrons and weak forces between the layers. b) Each graphene atom is bonded to three others in hexagonal rings arranged in layers - it has delocalised electrons and weak forces between the layers. c) Each carbon molecule is bonded to three others in hexagonal rings arranged in layers - it has delocalised electrons and weak forces between the layers. d) Each carbon ion is bonded to three others in hexagonal rings arranged in layers - it has delocalised electrons and weak forces between the layers. 11) Why can graphene conduct electricity? a) The delocalised ions can move through the graphite. b) The delocalised electrons can move through the graphite. c) The localised electrons can move through the graphite. d) The localised ions can move through the graphite. 12) Explain why graphite is soft. a) Layers are bonded so can slide over each other. b) Layers are bonded so cannot slide over each other. c) Layers are not bonded so cannot slide over each other. d) Layers are not bonded so can slide over each other. 13) What is graphene? a) Two layers of graphite. b) One layer of graphite. c) Two layers of carbon. d) One layer of carbon. 14) Give two properties of carbon. a) Strong, good insulator. b) Weak, conducts electricity. c) Strong, conducts electricity. d) Weak, good insulator. 15) What is a fullerene? a) Hollow cage of graphene ions arranged as a sphere or a tube. b) Hollow cage of carbon ions arranged as a sphere or a tube. c) Hollow cage of graphene atoms arranged as a sphere or a tube. d) Hollow cage of carbon atoms arranged as a sphere or a tube. 16) What is a nanotube? a) Hollow cylinder of carbon atoms. b) Hollow cylinder of carbon ions. c) Hollow cylinder of graphene atoms. d) Hollow cylinder of graphene ions. 17) Give two properties of nanotubes. a) Low tensile strength, conduct electricity. b) High tensile strength, conduct electricity. c) High tensile strength, good insulator. d) Low tensile strength, good indicator. 18) Give three uses of fullerenes. a) Dehydrators, drug delivery (cubic), high-tech electronics. b) Lubricants, drug testing (cubic), high-tech electronics. c) Lubricants, drug development (spheres), high-tech electronics. d) Lubricants, drug delivery (spheres), high-tech electronics.

Covalent bonding

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