bonding + structure

• what are the 3 main types of bonding?

  • ionic
  • covalent
  • metallic
• define ionic bonding 


  the electrostatic attraction between positive and negative ions
• example of ionically bonded substances 


  NaCl (sodium chloride - salt)
• define covalent bonding 


  electrostatic attraction between a shared pair of electrons and the nuclei
• Define metallic bonding 


  Electrostatic attraction between the positive metal ions and the sea of delocalised electrons
• why does giant ionic lattices conduct electricity when liquid but not when solid?


  In solid state the ions are fixed and can not move. When they are in a liquid state the ions can move and can therefore carry charge
• Giant ionic lattices have high or low melting and boiling point?

  they have a high melting and boiling point due to the large amount of energy to overcome the electrostatic bonds
• In what type of solvents do ionic lattices dissolve?

  Polar solvents

  E.g water
• Why are ionic compounds soluble in water?

  Water has a polar bond. Hydrogen atoms have + charge and oxygen atoms have a - charge. These charges are able to attract charged ions
• what is a lone pair?

  Electrons in the outer shell that are not involved in the bonding
• What is average bond enthalpy?

  Measure of average energy needed to break the bond
• what is a dative covalent bond?

  a bond where both of the shared electrons are supplied by one atom
• what types of covalent structure?

  • simple molecular lattice
  • giant covalent lattice
• describe the bonding in simple molecular structures?


  atoms within the same molecule are held by strong covalent bonds and different molecules are held by weak intermolecular forces
• why do simple molecular structures have low melting and boiling point?


  Small amount of energy is needed to overcome the intermolecular forces
• can simple molecular structures conduct electricity?

  no, they are non conductors
• why do simple molecular structures not conduct electricity?

  the have no free charged particles to move around
• simple molecular structures dissolve in what type of solvent?

  non polar solvents
• examples of giant covalent structures

  • diamond
  • graphite
  • silicon dioxide
• list properties of giant covalent structures?

  • high melting and boiling point
  • non conductor of electricity except graphite
  • insoluble in polar and non polar solvents
• how does graphite conduct electricity?

  Delocalized electrons carry the charge
• Why do giant covalent structures have high melting and boiling point?


  Strong covalent bonds within the molecules need to be broken which requires a lot of energy
• what does the shape of a molecule depends on?

  number of electron pairs in the outer shell

  number of these electrons which are bonded and lone pairs
• what is the, diagram and bond angle in a shape with 2 bonded pairs and 0 lone pairs?

  Linear, 180 degrees
• what is the shape, diagram and bond angle in a shape with 3 bonding pairs and 0 lone pairs?

  Trigonal planar, 120 degrees
• What is the shape, diagram and bond angle in a shape with 4 bonded pairs and 0 lone pairs?

  Tetrahedral, 109.5 degrees
• what is the shape, diagram and bond angle in a shape with 5 bonded pairs and 0 lone pairs?


  Trigonal bipyramid, 90 degrees and 120 degrees
• what shape, diagram and bond angle in a shape with 6 bonded pairs and 0 lone pairs?

  Octahedral, 90 degrees
• what is the shape, diagram and bond angle in a shape with 3 bonded pairs and 1 lone pair?

  Pyramidal, 107 degrees
• what is the shape, diagram and bond angle in a shape with 2 bonded pairs and 2 lone pairs?

  non linear, 104.5 degrees
• define electronegativity 


  the ability of an atom to attract the pair of electrons (the electron density) in a covalent bond
• which direction of periodic table does electronegativity increase?

  top right, towards fluorine
• what does it mean when the bond is non polar?


  the electrons in the bond are evenly distributed
• what is the most electronegative element?

  flourine
• what is meant by a intermolecular force?

  attractive force between neighbouring molecules
• what are the 2 types of intermolecular?

  hydrogen bonding, Van der waals' forces
• what is the strongest type of intermolecular?

  Hydrogen bonding
• what are the two types of interactions that can be referred to as Van der Waals' forces?

  • permanent dipole - induced dipole interaction
  • permanent - permanent dipole interaction
• Describe permanent dipole-induced dipole interactions

  • when a molecule with a permanent dipole is close to other non polar molecule it causes the polar molecules to become slightly polar leading to attraction
• Describe permanent dipole-permanent dipole interactions 


  some molecules with polar bonds have permanent dipoles = forces of attraction between those dipoles and those of neighbouring