Electrons, Bonding and Structure

• Linear shape

  2 bonding pairs, no lone pairs
• Linear bond angle

  180
• Trigonal planar shape

  3 bonding pairs, no lone pairs
• Trigonal planar angle


  120
• Tetrahedral shape

  4 bonding pairs, no lone pairs
• Tetrahedral angle

  109.5
• Trigonal pyramidal shape

  3 bonding pairs, 1 lone pair
• Trigonal pyramidal angle


  107
• Non-linear shape

  2 bonding pairs, 2 lone pairs
• Non-linear bond angle


  104.5
• Octahedral shape

  6 bonding pairs, 0 lone pairs
• Octahedral angle

  90
• Ionic bond


  Electrostatic attraction between oppositely charged ions
• Ionic compounds electrical conductivity

  conduct electricity when molten or dissolved in liquid as the ions are free to move and carry a charge
• Ionic compounds melting and boiling points

  High due to strong electrostatic forces
• Ionic compounds solubility

  dissolve in water as it is polar and able to pull ions away from the lattice
• Covalent bond


  A shared pair of electrons
• Dative covalent bond


  When one atom provides both of the shared electrons
• Electronegativity


  the ability of an atom to attract the pair of electrons in a covalent bond
• Polar molecules


  have an overall dipole
• temporary/ induced dipole-dipole interactions


  a slight temporary dipole forms due to the random movement of electrons, this induces a dipole in another molecule, which causes a chain reaction and the molecules to be attracted to each other
• permanent dipole-dipole interactions

  partial charges form weak electrostatic forces of attraction between molecules
• Hydrogen bonding


  lone pair on oxygen attracted to the delta positive hydrogen of another water molecule, this forms a hydrogen bond
• Ice is less dense than water


  As water freezes more hydrogen bonds form, as hydrogen bonds are relatively long this causes water molecules to be further apart and ice is therefore less dense than water
• Water has a relatively high boiling point


  As hydrogen bonds are so strong, they take a lot of energy in the form of heat to overcome
• where are electrons found

  orbitals
• where are orbitals

  in sub-shells
• where are sub-shells

  in shells
• Total number of electrons in 1st shell

  2
• Total number of electrons in 2nd shell

  8
• Total number of electrons in 3rd shell

  18
• Total number of electrons in 4th shell

  32
• spin-pairing


  electrons in an orbital spin in opposite directions
• number of p-orbitals in the p sub-shell

  3
• shape of s orbitals

  spherical
• shape of p orbital

  dumbbell shaped
• electron pair repulsion

  lone pair - lone pair repulsion > lone pair - bonding pair repulsion > bonding pair - bonding pair repulsion
• electrical conductivity of simple covalent compounds

  can't conduct electricity
• Melting and boiling points of simple covalent compounds

  intermolecular forces are weak so low melting and boiling points
• Solubility of simple covalent compounds

  Compounds with hydrogen bonds are soluble in water, molecules that aren't polar are not soluble in water