Cards (17)

  • DOT AND CROSS DIAGRAMS
    In these diagrams you only need to show the OUTER SHELL.
    • To represent atoms SHARING ELECTRONS, it has OVERLAPPING shells where the shared electrons are drawn.
  • DISPLAYED FORMULA:
    These are simplified diagrams that use LINES to represent COVALENT BONDS.
  • covalent diagrams
    A) hydrogen
    B) H-H
  • Covalent diagrams:
    A) chlorine
    B) Cl-Cl
  • covalent diagrams:
    A) oxygen
    B) O=O
  • covalent diagrams:
    A) nitrogen
    B) N≡N
  • covalent diagrams:
    A) hydrogen chloride
    B) H-Cl
  • covalent diagrams:
    A) water
    B) H-O-H
  • covalent diagrams:
    A) ammonia
    B) H-N-H
    C) H
  • covalent diagrams:
    A) methane
    B) H
    C) H-C-H
    D) H
  • 3D MODELS:
    To know the MOLECULAR FORMULA of a compound, count the number of each type of atom present in the molecule using any representation.
    • As there are 3 HYDROGEN atoms and 1 NITROGEN atom, this molecule has a formula of NH3.
  • limitations of ball and stick model:
    • not to scale
    • not 3D
    • atoms are separated
    • electrons / shells not shown
  • limitations of dots and cross diagrams:
    • does not show the shape
    • only 2D
  • It's CH4O
  • Because there are no gaps / sticks between the potassium ions and sulfide ions.
  • Covalent Bonding
    It occurs between non-metallic atoms, to form Simple molecular compounds.
    • It involves atoms SHARING pairs of electrons, so that the atoms can achieve a FULL OUTER SHELL and become STABLE.
    • They form because the positively charged NUCLEI are attracted to the shared pairs of ELECTRONS by ELECTROSTATIC FORCES.
  • In a water molecule, the hydrogen and oxygen atoms are held together by covalent bonds:
    • Each hydrogen atom requires 1 extra electron to complete its outer shell & wants to form 1 covalent bond.
    • While, each oxygen atom requires 2 more electrons & wants to form 2 covalent bonds. 
    Meaning water molecules will be made from 2 hydrogen atoms & 1 oxygen atom, so that all the atoms obtain full outer shells.