Bonding and type of substance.

• What are ionic bonds?

  ionic bonds are formed by the transfer of electrons between atoms to produce cations and anions.

  
• an ion is an atom or group of atoms with a positive or negative charge.
• Group 1 elements produce ions^+ because they have one electron in their outer shell and lose that one electron to have a full outer shell. This makes them positively charged as there are more protons than electrons so charges are not balanced.
• Group 2 elements produce ions^2+ because they have two electrons in their outer shell and lose 2 electrons to have a full outer shell to become positively charged.
• Group 7 elements produce ions^- because they have 7 electrons in their outer shell and gain an electron to have a full outer shell and become negatively charged because there are more electrons than protons.
• Group 6 elements produce ions^2- because they gain two electrons to have a full outer shell
• What is oxide?

  $O^2-$
• What is Hydroxide?

  $OH^-$
• What is Halide?

  $F^-$
• What is carbonates?

  $CO3^2-$
• What is sulphates?

  $SO4^2-$
• What is the structure of an ionic compound?

  A lattice structure consisting of a regular arrangement of ions held together by strong electrostatic forces (ionic bonds) between oppositely charged ions.
• A covalent bond is formed when a pair of electrons is shared between two atoms.
• Covalent bonding results in the formation of simple molecules.
• A dot and cross diagram show the structure of a molecule and the bonds between the atoms.

  
• Simple molecules are tiny — they generally have sizes around 10-10 m. The bonds that form between these molecules are generally about 10-10 m too.
• How can elements be classified as an ion?

  By gaining or losing electrons, elements can become ions. Usually a metal with a non-metal.
• How can elements be classified as simple molecules (covalent bonds)?

  The sharing of electrons which creates a strong bond.
• How can elements be classified as giant covalent?

  By having a network of covalent bonds throughout a large structure.
• How can elements be classified as metallic bonds?


  By having a delocalized sea of electrons that are shared among a lattice of positively charged metal ions.
• What are the properties of ionic compounds?

  High melting and boiling points due to strong electrostatic forces of attraction.

  Bad conductors of electricity as the ions are in a fixed place. But when an ionic compound melts or dissolves in water, the ions are free to move and can carry an electric charge.

  They can dissolve easily.
• What are the properties of covalent molecules?

  They have a low melting and boiling point because they have weak intermolecular forces.

  They are poor conductors of electricity because they do not have free electrons.

  
• Graphite and diamond are the different forms of carbon. They are both giant covalent structures.
• What is the structure of a diamond?


  diamond is very hard because it contains very strong covalent bonds - giving it a very high melting point. It is a rigid lattice structure.

  It contains 4 covalent bonds

  It does not conduct electricity.
• What is the structure of graphite?

  The structure of graphite consists of layers of carbon atoms arranged in a hexagonal lattice.

  It contains 3 covalent bonds and 1 delocalized electron making it conductive.

  It is soft and slippery because it is held with weak covalent bonds between the layers.
• Graphite is used to make electrodes because it is a good conductor as it has 1 delocalised electron. Diamond is good for cutting because it is hard and strong due to its strong covalent bonds.
• Graphene is a type of fullerene which is 1 layer of graphite and can be used as industrial catalysts.
• Buckminsterfullerene is a type of fullerene that has the molecular formula C60. It has a low melting point due to its weak intermolecular forces.

  
• What are the properties of metals?

  Conductive and malleable because the layers of ions are able to slide over each other.
• what are the limitations of each diagram?

  Dot and cross: does not show anything about the size of the atoms.

  3D diagrams: only show the outer layer of each substance.
• most metals are shiny solids that have high melting points, high density, and are good conductors of electricity whereas most non-metals have low boiling points and are poor conductors of electricity.