C2 Bonding

• Forming Ions


  An ion is an atom or molecule with a positive or negative charge
• Atoms lose or gain electrons to form ions
• Positive ions


  • Metal atoms lose electrons from their outer shell
  • They form positively charged ions
• Negative ions


  • Non-metal atoms gain excess electrons
  • They form negatively charged ions
• Positive ions have fewer electrons than protons
• Negative ions have more electrons than protons
• Ions have a full outer shell of electrons
• For elements in groups 6 and 7, the charge on the ion is equal to (8 minus group number)
• Chlorine


  7 electrons in outer shell
• Covalent bonds


  • Shared electrons between atoms
  • Gives each atom a full outer shell
• Covalent bonding


  • Methane
  • Water
• Metallic bonding


  Delocalized electrons shared between positive metal ions
• Metallic bonding


  • Produces a regular arrangement (lattice) of positive ions
  • Held together by electrostatic attraction to delocalized electrons
• Alloys


  Mixtures of metals that contain one or more added elements
• Alloys


  • Added element disrupts the regular arrangement of the metal
  • Layers do not slide over each other as easily
  • Alloys are usually stronger and harder than pure metals
• Most metal objects are not made from pure metals but from alloys
• Covalent bonds are very strong
• Some covalently bonded substances consist of small molecules
• Metallic bonding occurs in metallic elements, such as iron and copper
• Metallic bonding produces a regular arrangement (lattice) of positive ions held together by electrostatic attraction to delocalized electrons
• Polymers


  Very large molecules consisting of many small molecules called monomers joined together
• Making polymers


  Joining thousands of small molecules called monomers
• Monomers


  • Small molecules that make up polymers
• Polymer bonds


  • Single covalent bonds between carbon atoms
  • Extremely strong bonds
• Polymers


  • Too large to pass through a membrane
  • Have a double carbon-carbon bond
• Most polymers are solids at room temperature
• Intermolecular forces in polymers

  • Responsible for polymers having a high melting point
  • Require a lot of energy to break
• Breaking intermolecular forces in polymers

  1. Requires a lot of energy

  2. Allows polymers to melt