revision BONDING

• what is ionic bonding?


  oppositely charged ions held together by electrostatic attraction.
• what is OH-


  hydroxide
• what is No3-


  nitrate
• what is NH+4


  ammonium
• what is SO2- 4


  sulfate
• what is CO2- 3


  carbonate
• what is the structure of ionic compounds?


  • giant ionic structure
  • regular structure
  • cubic shape
  • giant repeating pattern
• what are ionic compounds like in water?


  they mostly dissolve in water, bc water molecules are polar so can attract the positive and negative ions and break up the structure.
• can ionic compounds conduct electricity? why?


  ionic compounds can conduct electricity when molten or dissolved because the ions are free to move around.
• why do ionic compounds have high melting points?


  they have strong electrostatic forces between the oppositely charged ions so lots of energy are needed to overcome the forces.
• what is covalent bonding?


  the sharing of outer electrons in order for atoms to obtain a full outer shell.
• what forces of attractions are in covalent bonds and where are they?


  electrostatic forces of attraction between the shared electrons and the positive nucleus.
• what types of bonds are there in covalent bonds?


  single, double and triple. All share different numbers of electrons.
• what is dative covalent bonding?


  where on atom donates 2 electrons to an atom/ion to form a bond, eg: NH+4
• what represents a dative bond?


  an arrow.
• what are 2 examples of giant covalent structures?


  graphite and diamond
• what are the carbon atoms like in graphite?


  each carbon atom is bonded three times, the fourth electron is delocalised.
• why does graphite have a high melting point?


  lots of strong covalent bonds to overcome.
• why do the graphite layers slide easy?


  weak forces between the layers.
• can graphite conduct electricity?

  yes, because the delocalised electrons can carry a charge.
• why can graphite conduct electricity and not diamond?


  graphite has delocalised electrons but diamond doesn’t.
• why does graphite have a low density?


  the layers are far apart.
• why is graphite insoluble?

  covalent bonds are too strong to break.
• what are the carbon atoms like in diamond?


  each carbon atoms bonded four times.
• what shape is the diamond molecule?


  tetrahedral shape.
• why does diamond conduct heat?


  tightly packed rigid arrangement.
• can diamond be cut?


  yes can be cut to make gemstones.
• why does diamond have a high melting point?


  because strong covalent bonds to overcome.
• is diamond hard or soft?


  hard.
• why doesn’t diamond conduct electricity?


  diamond has no delocalised electrons to carry a charge.
• why is diamond insoluble?


  covalent bonds too strong to break.
• how do we work out the shape of a molecule?


  work out the number of bonded electron pairs and number of lone electron pairs.
• what is the order of pairs repelling?


  lone pair + bond pair > 2 bond pairs > 2 lone pairs.
• what is the generalisation for every lone pair angle?


  generally, every lone pair reduces bond angle by 2.5 degrees.
• what is electronegativity?


  the ability for an atom to attract electrons towards itself in a covalent bond.
• how can we look at a periodic table and see the most electronegative elements?


  top right periodic table, but not the noble gases.
• what is the most electronegative element?


  Fluorine.
• what is the table showing electronegativity?


  the Pauling Scale.
• how can covalent bonds become polar?


  if the atoms attached have a difference in eletronegativity
• the bigger the electronegativity difference…


  …the more polar the bond.