1.03 Bonding

• what is a covalent bond?

  a chemical bond formed between two atoms sharing electrons to fill their outershells. the positive nuclei are electrostatically attracted to the shared electrons.
• what are giant covalent structures?

  giant covalent structures have huge networks of covalently bonded atoms. carbon often forms this type of structure because they can each form four strong covalent bonds
• name three giant covalent structures

  diamond, graphite, silicon dioxide
• describe the structure of graphite

  graphite has a giant covalent molecular structure it contains many layers of carbon atoms each carbon atom covalently bonded to three other carbon atoms.

  
  

  the layers are held by weak van der waal forces that are easily broken so its malleable and is used as a dry lubricant.

  
  

  delocalised electrons are free to move and carry charge so its a good electrical conductor.

  
  

  strong covalent bonds make it insoluble and give it a high melting point.

  
  

  the layers are far apart so it has a low density and is used to make strong lightweight sports equipment.
• describe the structure of diamond

  diamond has a giant molecular structure with carbon atom covalently bonded to four others.

  
  

  the strong covalent bonds make it insoluble, give it a high melting point, and a hard structure so its used in drills.

  
  

  vibrations travel easily through the stiff lattice so its a good thermal conductor.

  
  

  outer electrons are held in localised bonds so cannot conduct electricity.
• what is a dative covalent bond?

  a covalent bond in which a shared pair of electrons is supplied by only one of the bonding atoms
• what is ionic bonding?

  electrostatic attraction between oppositely charged ions in a lattice
• what is ammonium?

  NH4 +
• what is carbonate?

  CO3 2-
• what is hydrogen carbonate?

  HCO3 -
• what is hydrogen sulphate?

  HSO3 -
• what is hydroxide?

  OH -
• what is nitrate?


  NO3 -
• what is nitrite?

  NO2 -
• what is sulphate?

  SO4 2-
• what is sulphite?

  SO3 2-
• what is chlorate (i) ?

  CLO -
• what is chlorate (v) ?

  ClO3 -
• what is vandanate (v) ?

  VO3 -
• what is manganate (vii) ?

  MnO4 -
• what is chromate (vi) ?

  CrO4 2-
• what is dichromate (vi) ?

  Cr2O7 2-
• what is metallic bonding?

  the chemical bonding that results when the outer energy level electrons are delocalised which leaves positive metal ions that are attracted to the electrons
• what happens to covalent bonds during melting/boiling?

  nothing, they dont break unless its a giant covalent
• what are melting and boiling points determined by?

  the attraction between particles e.g. intermolecular and electrostatic forces
• when will substances conduct electricity?

  if there are charged particles free to move
• solubility depends on?

  the type of particle. water is a polar solvent so polar or charged substances will dissolve but non polar or uncharged wont
• what are the properties of monatomic structures?

  • noble gases that exist as single particles e.g. helium and neon.• low melting/boiling points due to weak IMF. • non conductive.• insoluble.
• what are the properties of simple molecular structures?

  e.g. carbon dioxide and methane.

  
  

  low melting/boiling points due to weak IMF.

  
  

  non conductive.

  
  

  mostly insoluble.
• what are the properties of giant covalent structures?

  • e.g. diamond and silicon dioxide.• high melting/boiling points due to strong covalent bonds.• non conductive except graphite.• insoluble.
• what are the properties of ionic compounds?

  • giant ionic lattices e.g. sodium chloride.• high melting/boiling points due to strong electrostatic forces.• only conducts when molten or in solution.• soluble.
• what are the properties of metallic structures?

  • e.g. gold and magnesium.• high melting/boiling points due to strong electrostatic forces.• good conductor. • insoluble.
• do ionic bonds form molecules?

  no
• are IMFs weaker or stronger than covalent, ionic, and metallic bonds?

  weaker.
• what are the three types of IMFs?

  • dipole-dipole (permanent) • induced dipole-dipole / van der waals • hydrogen bonding
• what type of molecules have a permanent dipole?

  polar molecules
• what type of molecule can create instantaneous dipoles and why?

  non polar molecules due to the random motion of electrons, when electrons aren't evenly distributed they can create a negative charge for a short time.
• how are induced dipoles formed?

  when a non polar molecule is next to a polarised molecule with either an instantaneous or permanent dipole, the negative polarised charge repels electrons in unpolarised molecules to induce a dipole.
• how are van der waal forces formed?

  instantaneous dipoles cause other instant dipole to form creating a domino effect. the forces are always being created and destroyed but overall the atoms stay attracted.
• how strong are VDWs in comparison to covalent bonds?

  1/100th the strength of a covalent bond