2.1: bonding, structures, properties

• What are compounds?

  Substances with 2 or more chemically combined elements
• How many types of strong chemical bonds are there?

  Three
• What type of bonding is present in ionic compounds?

  Ionic bonding
• What type of bonding is present in metals?

  Metallic bonding
• What type of bonding is present in giant covalent structures?

  Covalent bonding
• How does the type of bonding affect a compound's properties?

  It accounts for physical and chemical properties
• Between which types of elements does ionic bonding occur?

  Metals and non-metals
• What are ionic bonds?

  Electrostatic attractions between oppositely charged ions
• What structure do ions form in ionic compounds?

  A giant ionic lattice
• What happens to metal atoms during ionic bonding?

  They lose electrons to become positively charged ions
• What happens to non-metal atoms during ionic bonding?

  They gain electrons to become negatively charged ions
• How can electron transfer in ionic compounds be represented?

  By a dot and cross diagram
• Why do ionic compounds have high melting and boiling points?

  Due to strong electrostatic attractions between ions
• Why do solid ionic compounds not conduct electricity?

  Because ions are fixed in place
• When can ionic compounds conduct electricity?

  When molten or dissolved
• What is a property of ionic compounds?

  They are brittle
• What do metals consist of?

  Giant structures of positive metal ions
• What happens to the electrons in metal atoms?

  They are delocalised and free to move
• What forms metallic bonds?

  Electrostatic attraction between metal ions and electrons
• Why are metals malleable and ductile?

  Layers of ions can slide over each other
• Why do metals conduct electricity and heat?

  Delocalised electrons can carry charge
• Why do most metals have high melting and boiling points?

  Metallic bonds are very strong
• What forms when atoms share pairs of electrons?

  Covalent bonds
• What types of compounds can consist of small molecules?

  Covalently bonded compounds
• What are giant covalent structures?

  Large molecules linked by strong covalent bonds
• How can covalent bonding be represented?

  Dot and cross diagrams, ball and stick models
• What are simple molecules usually in terms of state?

  Gases or liquids with low boiling points
• What type of forces exist between simple molecules?

  Weak intermolecular forces
• What happens to intermolecular forces as molecule size increases?

  They increase, leading to higher melting points
• Why don’t simple molecules conduct electricity?

  They have no overall electric charge
• What are the properties of giant covalent structures?

  Solids with very high melting points
• What must be overcome to melt or boil giant covalent structures?

  Strong covalent bonds
• What are allotropes?

  Different forms of the same element
• How many other carbons does each carbon bond with in diamond?

  Four
• What are the properties of diamond?

  Very hard, high melting point, non-conductive
• How many other carbons does each carbon bond with in graphite?

  Three
• What structure does graphite form?

  Layers of hexagonal rings
• Why is graphite soft and slippery?

  Weak intermolecular forces between layers
• What allows graphite to conduct electricity?

  Delocalised electrons from carbon atoms
• What is graphene?

  A single layer of graphite