Bonding, Structure and Properties of Matter

• Polymers


  • Have very large molecules
  • The bonds in the polymer molecules are linked to other atoms by strong covalent bonds
  • The intermolecular forces between polymer molecules are relatively strong, so they are solids at room temperature
• Metallic bonding


  • Occurs in metals
  • Metals have giant structures of atoms with strong metallic bonding
  • The electrons in the outer shell of metal atoms are delocalised and free to move through the whole structure
  • The sharing of delocalised electrons gives rise to strong metallic bonds
• Bonding


  Gives atoms a stable arrangement of electrons (full outer shell) like the noble gases
• Types of bonding


  • Ionic
  • Covalent
  • Metallic
• How metals form ions

  1. Atoms lose electrons in their outer shell forming positive ions

  2. The number of electrons lost depends on the group they are in
• How non-metal atoms form ions

  1. Non-metals gain electrons in their outer shell forming negative ions

  2. The number of electrons gained depends on the group they are in
• Negatively charged ions


  Have the end of the element name replaced with -ide
• Ionic bonding


  • Occurs between a metal and a non-metal to form a compound
  • The metal loses electrons to achieve a full outer shell and forms a positive ion
  • The non-metal gains electrons to achieve a full outer shell and forms a negative ion
  • The oppositely charged ions are attracted to each other by a strong force called electrostatic attraction
  • The structure formed is called a giant ionic lattice
• Dot and Cross model fails to illustrate the 3D arrangement of the lattice structure and cannot indicate the relative sizes of the ions
• Ball and Stick model shows gaps between ions and only illustrates the outermost layer of the compound
• Two dimensional models only show a tiny part of the lattice structure and do not give the 3D structure of the ionic compound
• Properties of ionic compounds

  • High melting and boiling point
  • Conducts electricity when molten or dissolved in water
  • Does not conduct electricity when a solid
  • Usually white, solid (Transition metal compounds are coloured)
  • Soluble in water
• Solubility of ionic compounds

  • Ionic compounds easily dissolve in water to form aqueous solutions
  • As an ionic compound dissolves, its ionic lattice breaks up, and the ions are free to move
• High melting and boiling points of ionic compounds


  • Due to the strong electrostatic force of attraction between oppositely charged ions in all directions
  • Large amounts of energy are needed to break the many strong bonds
• Electrical conductivity of ionic compounds

  • Solid ionic compounds do not conduct electricity because ions are in fixed positions and only vibrate on the spot, and ions cannot carry electrical charge
  • Molten ionic compounds and ionic compounds dissolved in water conduct electricity because ions are free to move and can carry electrical charge
• Covalent bonding


  • Occurs between two or more non-metals
  • When atoms share pairs of electrons, they form covalent bonds
  • These bonds between atoms are strong
• Covalently bonded substances


  • Small molecules
  • Polymers
  • Giant covalent structures
• Covalent bonds do not have charged projections
• Dot and Cross model does not show the shape, is only two dimensional, and doesn't show which atom the electrons in the bond originally come from
• Ball and Stick model doesn't show the 3D structure and is not to scale
• Giant covalent structures


  • Substances that consist of giant covalent structures are solids with very high melting points
  • All of the atoms in these structures are linked to other atoms by strong covalent bonds
• Diamond


  • A giant covalent structure made only from carbon atoms
  • Each carbon atom is bonded to four other carbon atoms
• Uses of diamond


  • Laser beam
  • Cutting tools and drills
• Properties of diamond


  • Very hard
  • Does not conduct electricity
  • High melting point
• Why diamond is hard


  Giant covalent structure with each carbon atom bonded to four other carbon atoms by strong covalent bonds
• Why diamond does not conduct electricity

  Each carbon atom is bonded to four other carbon atoms, so there are no free electrons to carry electrical charge
• Why diamond has a high melting point

  Giant covalent structure with four strong covalent bonds for each carbon atom, requiring a lot of energy to break the bonds
• Silicon dioxide (silica)


  • Giant covalent structure made from silicon and oxygen
  • Each oxygen atom is bonded to two silicon atoms and each silicon atom is bonded to four oxygen atoms by strong covalent bonds
• Uses of silicon dioxide


  • Lining for furnace
• Why silicon dioxide has a high melting point

  Giant covalent structure with many strong covalent bonds which require a lot of energy to break
• Graphite


  • A giant covalent structure only made from carbon atoms
  • Arranged in hexagonal layers with weak intermolecular forces between layers
• Why graphite is soft

  There are only weak intermolecular forces between the layers, allowing the layers to slide over each other
• Why graphite conducts electricity

  Each carbon is bonded to three other carbon atoms, with one delocalised electron per carbon atom that can move through the structure and carry electrical charge
• Why graphite conducts thermal energy

  Each carbon is bonded to three other carbon atoms, with one delocalised electron per carbon atom that can move through the structure and transfer thermal energy
• Why graphite has a high melting point

  Giant covalent structure with three strong covalent bonds to each carbon atom, requiring a lot of energy to break the bonds
• Graphene


  • A giant covalent structure made of a single layer of graphite
  • Each carbon atom forms three strong covalent bonds
• Why graphene conducts electricity

  One delocalised electron per carbon atom that can move through the structure and carry electrical charge
• Why graphene is strong

  Giant covalent structure with each carbon atom bonded to three other carbon atoms by strong covalent bonds, requiring a lot of energy to break
• Uses of graphene


  • Electronics
  • Composites
• Properties of graphene


  • Low density
  • Transparent