Test 2 - covalent bonding & metals

• polar

  unbalanced/asymmetrical
• non-polar


  equal/symmetrical
• covalent bonding

  non-metal + non-metal
• dispersion forces


  intermollecular bonding that happens for all molecules
• strength of dispersion forces are affected by:

  bigger size = stronger force, closer packed shape = stronger force
• disp in polar vs non-polar

  polar = disp + more, non-polar=disp only
• S+ and S- meanings

  S+ is the atom with smaller num. of electrons, S- is the atom with a larger num. of electrons
• electrovalency

  ability of an atom to attract electron
• polarity

  level of difference between the electrovalencies of 2 atoms
• electron density?

  measure of the probability of an electron being present at a particular location within an atom
• dipole

  points towards negative end

  
• dipole-dipole attraction

  attraction of positive and negative ends of polar molecules

  stronger than dispersion
• hydrogen bonding

  HNOF

  strongest intermolecular bond
• 4 bonding pairs

  tetrahedral
• 3 bonding pairs

  pyramidal
• 2 bonding pairs

  bent
• 1 bonding pair

  linear
• intramolecular

  covalent bonding
• intermolecular

  disp/dip-dip/h-bond
• molecule

  small group of non-metal atoms covalently bonded
• hard & high boiling point of metals

  due to strong electrostatic forces of attraction between metal cations and delocalised electrons
• malleable and ductile

  layers of cations can be rearranged provided the e- continue to surround without breaking bonds (delocalised e- are free moving)
• conduction

  conducts as delocalised e- are free to move + carry current
• shiny/lustre

  delocalised e- reflect light
• what group is most reactive?

  group 1 (decreasing to the right)
• diamond covalent bonds

  4
• diamond conductivity of electricity + heat

  cannot conduct electricity as particles are not free movingconducts heat due to carbon atoms strong bonds within the lattice
• graphite covalent bonds

  3
• graphite conductivity of electricity + soft

  conducts electricity as delocalised e- are free moving between layers

  soft due to layered lattice shape with weak dispersion forces that allows layers to slide over each other without breaking bonds
• sublime


  solid to gas
• diamond and graphite sublime

  above 3500°C due to strong covalent bonds
• covalent

  non-metal + non-metal
• why do metals form positive ions

  metals are very electropositive, and their outer electrons are very loosely bunded on them