Chem Question

• unclebutcher

  2 Jul 07, 21:35

  Originally posted by DC+:

  i think biology is the easiest..then physics and chem
  
  maybe depends on your lecturers

  \
  
  i nvr do bio b4...but i heard its memorise confirm a1
• Darkness_hacker99

  2 Jul 07, 22:14

  Originally posted by unclebutcher:

  \
  
  i nvr do bio b4...but i heard its memorise confirm a1

  to a certain degree.. yup need memorizing.
• kct360

  5 Jul 07, 18:15

  but to memorize ar... got alooot of things to memorize.
• lpx88

  23 Jul 07, 19:19

  K i have another qn, this time is on ionic bonds
  
  An ionic bond btw Na+ and Cl-
  
  Why they say in the NaCl crystal, the lattice structure has each Na+ ion surrounded by SIX Cl- ion ah? Why SIX?Not other number like 7,8,9..bla bla bla?
• unclebutcher

  23 Jul 07, 19:28

  Originally posted by lpx88:

  K i have another qn, this time is on ionic bonds
  
  An ionic bond btw Na+ and Cl-
  
  Why they say in the NaCl crystal, the lattice structure has each Na+ ion surrounded by SIX Cl- ion ah? Why SIX?Not other number like 7,8,9..bla bla bla?

  not sure if you have studied it...but coordination number of na is 6 . i.e. it can have a max of 6 cl- ions surrounding it
• teraexa

  25 Jul 07, 20:25

  It is all about the packing effect of ions.
  
  There's Face-Centered Packing, Cubic-Centered Packing.
  
  They're, however, out of A and O level syllabus and thus no need to bother about them.