Chem topic 8

• what is the first step of drawing lewis structures

  find the central atom
• what atom should be the central atom?

  the one closest to carbon, has better bonding capacity
• what should never be a central atom?

  hydrogen
• what should happen before placing electrons

  count total number of valence electrons each atom will bring
• if a molecule has a positive charge...


  take away electron
• if a molecule has a negative charge...

  add electron
• each bond is...

  two electrons
• total number of electrons should be...

  even
• you should start placing electrons from...

  the outside in
• you should only add electrons to the central atom...


  last
• what should be fulfilled?

  the octet rule
• if the octet rule is not fulfilled, you can add...

  double or triple bonds
• how do double or triple bonds form?

  take from a lone pair
• what atom is an exception to the octet rule?

  hydrogen
• bonding capacity

  better number of electrons for bonding
• formal charge

  number of valence electrons it wants minus valence it has
• all charges want to be as close to _ as possible

  zero
• all molecules want as many ___ as possible

  zero formal charges
• formal charges won't always be _, but should be as close as possible

  zero
• more _ atoms will have __

  electronegative, more bonds
• never add lone pairs to what atom?

  hydrogen
• lightweight/smaller atoms do not have to follow the...

  octet rule
• C-F always...

  follow the octet rule
• atoms in row 3 or heavier can have...

  more than an octet