bonding

• Ionic bonding


  electrostatic force of attraction between oppositely charged ions
• ionic crystals have giant lattice structure
• Ionic bonding are stronger and have higher melting point when ions are smaller or have higher charges
• Positive ions are smaller compared to their atoms because it has one less shell of electrons and the ratio of protons to electrons has increased so there is greater net force on the remaining electrons holding them
• covalent bonding 


  shared pair of electrons
• Dative covalent 


  shared pair of electrons in the covalent bond is come from one of bonding pair
• Metallic bonding 


  electrostatic forces between positive ions and delocalised electrons
• Factors that affect metallic bonding

  • number of protons
  • number of delocalised electrons per atom
  • size of atom
• structure of covalent bonding

  simple molecular
• structure of ionic bonding

  giant ionic lattice
• structure of covalent bonding (big)

  macromolecular
• structure of metallic bonding

  giant metallic lattice
• why can't macromolecules and molecular structures conduct electricity when solid

  electrons can't move
• how are metals malleable

  identical positive ions in the lattice, planes can slide easily over one another, attractive force in the lattice are the same whichever ions are adjacent
• 2 bonding pair, no lone pairs

  linear 180'
• 3 bonding pairs, 0 lone pairs

  trigonal planar 120'
• 4 bonding pairs , 0 lone pairs

  tetrahedral 109.5
• 3 bonding pair, 1 lone pair

  trigonal pyramidal 107
• 2 bonding pair, 2 lone pairs

  bent 104.5
• 5 bonding pairs , 0 lone pairs

  trigonal bipyramidal 120, 90
• 6 bonding pairs , 0 lone pairs

  octohedral 90
• lone pairs repel more than bonding pairs, reduces bond angles
• 4 bonding pairs, 2 lone pairs

  square planar 90
• 2 bonding pairs, 3 lone pairs

  linear 180
• electronegativity


  relative tendency of an atom in a covalent bond in a molecule to attract electrons in a covalent bond go it self
• electronegative increases across a period as no. of protons increases, same shielding
• electronegativity decreases down the group as atom becomes bigger, more shielding
• formation of permanent dipole

  polar covalent bond forms when the have different electronegativities, unequal distribution of electrons in the bond lead to dipole
• symmetrical molecules 


  will not be polar, individual dipoles cancel out
• van der waals 


  random movements of electrons causes electron density to fluctuate. Temporary dipoles form, induces dipoles in neighbouring molecules
• More electrons, stronger Van der Waals, higher the chances that temporary dipoles will form
• Permanent dipole dipole 


  occurs between polar molecules, asymmetrical where there is significant difference in electronegativity
• Hydrogen bonding occur between N, O, F, H. There is a large electronegativity difference
• bonding pairs repel and try to get as far apart as possible