MOLECULAR BONDING

• Name the molecular shape that has 2 bonding pairs and a angle of 180º


  Linear
• Name the molecular shape that has 3 bonding pairs and a angle of 120º


  trigonal planar

  
• Name the molecular shape that has 4 bonding pairs and a angle of 109.5º


  tetrahedral

  
• Name the molecular shape that has 3 bonding pairs and 1 lone pair of electrons and an angle of 107º


  Trigonal Pyramidal

  
• Name the molecular shape that has 2 bonding pairs and 2 lone pair of electrons and an angle of 104.5º


  bent/angular
• Name the molecular shape that has 5 bonding pairs and an angle of 90 and 120º


  Trigonal bipyramidal

  
• Name the molecular shape that has 6 bonding pairs and a angle of 90º


  octahedral
• Name the molecular shape that has 4 bonding pairs and 2 lone pair of electrons and an angle of 90º


  Square Planar

  
• XeF4 has 4 bonding pairs and 2 lone pairs around Xe, giving it a square planar shape
• PF3 has 3 bonding pairs and 1 lone pair around P, giving it a pyramidal shape
• Electron pairs repel as far as possible, with lone pairs repelling more than bonding pairs
• XeF4 exhibits van der Waals forces, while PF3 exhibits dipole-dipole forces (and van der Waals forces)
• XeF4 has stronger or more intermolecular forces compared to PF3
• This difference in intermolecular forces is due to XeF4 having a larger molar mass, more electrons, larger molecules, or packing more closely together
• definition ionic bonding

  an ionic bond is the electrostatic force of atraction between oposite charged ions formed by electron tansfer
• When do ionic bonding is stronger and has higher melting points?

  • ions are smaller
  • higher charges
• definition covalent bond

  A covalent bond is between two non metal atoms whom share one or more pair of electrons and have a strong atraction between the nucleus and the shared electrons
• definition dative/ co-ordinate covalent bond

  When two non metal atoms share a pair of electrons coming from only one of the bonding atoms
• Where does go the direction of the arrow in a dative covalent bond?

  It goes from the atom that is providing the lone pair to the atom that is deficient
• definition of metallic bonding

  Is the electrostatic force of atracction between the positive metal ions and the delocalised electrons
• Name the 3 main factors that affect the strenght of a metallic bond

  1. Number of protons -} strenght of nuclear attraction
  2. Number of delocalised electrons ( outer shell electrons are delocalised) per atom
  3. Size of the ion -} the smaller the ion, the stronger the bond
• Name the bonding structure of covalent bonding and name two examples

  Simple molecular

  • VdW forces
  • Permanent or temporary dipole-dipole forces
  • Hydrogen bonds

  $I_2$IODINE

  $H_2O$ICE
• Name the bonding structure of ionic bonding and name two examples

  Giant Ionic Latice

  $NaCl$Sodium Chloride

  $MgO$Magnesium Oxide
• Name the bonding structure of covalent bonding and name two examples



  Giant metallic latice

  $Mg$

  $Na$Magnesium, Sodium(all metals)

  
• Name the bonding structure of covalent bonding and name two examples


  Mcromolecular

  $C(s,diamond)$

  $C(s,graphite)$

  
• When do we use the words molecules and intermolecular forces?

  When talking about simple molecular substances
• Does ionic bonding has high or low boiling and melting point? Why?

  It has high boiling and meting points because of the giant ionic lattice of ions with strong electrostatic forces between opositely charged ions.

  
• Does covalent simple molecular bonding has high or low boiling and melting point? Why?

  Low because of week intermolecular forces between molecules (VdW, dipole-dipole, hydrogen bonding)

  
• Does covalent macromolecular bonding has high or low boiling and melting point? Why?


  High because there are many strong covalent bonds in a macromolecular structure; therefore requires lots of energy to break the many strong bonds

  
• Does metallic bonding has high or low boiling and melting point? Why?

  High because of the strong electrostatic forces between positive ions and sea of delocalised electrons

  
• Is ionic bonding a good or bad soluble in water and can it conduct electricity when solid and molten?

  Water: Generally good

  Conductivility when solid: Poor (ions can´t move because they are fixed in the giant ionict lattice)

  Conductivility when molten: Good( the ions that make it up are free to move within the substance and carry charge through it)

  Generally: Cristalline solids
• Is covalent molecular simple bonding a good or bad soluble in water and can it conduct electricity when solid and molten?


  Water: Generally poor

  Conductivity when solid: Poor ( no ions to conduct and electrons are localised)

  Conductivility when molten: Poor ( no ions)

  Generally: Gases and liquids
• Is covalent macromolecular bonding a good or bad soluble in water and can it conduct electricity when solid and molten?

  Water:

  Conductivity when solid: Diamond and sand poor because electrons are localised but in graphite is good because it has delocalised electrons between layers

  Conductivity when molten: Poor

  Generally: solids
• Is metallic bonding a good or bad soluble in water and can it conduct electricity when solid and molten?

  Water: Insoluble

  Conductivity when solid: Good (delocalised electrons are free to move)

  Conductivity when molten: Good

  Generally: Shiny metals

  Malleable as the positive ions in the lattice are all identical. So the planes can slide easily over one other.

  Attactive forces in the lattice are the same wichever ions are adjacent.
• DEFIINE ELECTRONEGATIVITY

  Is the relative tendency of an atom in a covalent bond in a molecue to attract electrons in a covalent bond to itself
• How is measured electronegativity

  In Pauling scale (range 0-4)
• Name the 2 factors that affect electronegativity

  • Increases across a period as the number of protons increases and the atomic radius decreases down a group because the electrons in the same shell are pulled in more
  • It decreases down a group because the distance between the nucleus and the outer electrons increases and the shielding of inner shell electrons increases
• A compund containing elements of similar electronegativity and hance a small electronegativity difference willl be purely covalent
• A compund containing elements of different electronegativity and hance a very large electronegativity difference ( > 1.7) willl be ionic
• A polar covalent bond forms when the elements in the bond have different electronegativities (o.3 to 1.7) having a unequal distribution of electrons in the bond and produces a charge separation ( dipole ends)