Thurs 6:15-7:15; Recitation in 204 NS

Bicarbonate CHO3- (HCO3-)

• anion
• Map: H-O-C-O
• O

1. total # valence e-= 1(4)+1(1)+3(6)+1 = 24
2. 24-8(used e-) = 16; 18-16 used = 2, so need another bond; put between the oxygen & carbon (ie double bond

There are two ways to check your bonds:

1. Count total number of electrons
2. count the octets

Formal charge on atom = group #-sum of (# non-bonded e- + #bonds to atom)

• Sum of the formal charges = total charge of the ion or molecule

Other formulas

• condensed formulas:
  • shorthand for organic chemists
  • eg: butanol (C4H12O
  • H3CH2CH2CH2CH2OH
    • with a vertex there is enough H's to complete the octet rule
    • /\/\OH (line up, line down, up, down, OH attached)
  • cyclo pentane
    • C7H14
    • this structure does not appear as the condensed formula indicates because the structure is 3d

As you go across the periodic table you are increasing effective nuclear charge.

• Hot spot is upper right because small with lots of free e- (Carbon)
• compare ethane (3H:C::C:H3)
• with 3H:C::F
  • more electronegative
  • fluorine is more negative because it pulls the electron towards it;
    • sigma - charge of -0.2
  • the carbon is more positive because it looses partial control over the electron
    • sigma + charge of +0.2

molecular dipole moment = vector sum of individual bond dipole moments

• some molecules like CO2 (O::C::O) has differences in electronegativity (C is +, both O are -) have a molecular dipole of 0.00 because of the geometry (180 degrees apart).

Acid dissociation

• Cl-H <-> Cl- + H+
• Bronsted Acid is a chemical which is a source of H+ protons
  • note: the H+ is not the Bronsted

• Acid dissociation constant:
  • Ka = [products]/[reactants] = (left side of arrow [Cl-][H+])/([HCl] right side)
  • Ka(Hcl) ~ 10^6
• CH4 as a Bronsted acid:
  • CH4 --> H3C:- + H+
    • do not represent a balanced formula with a single double arrow; always use 2 because single is something else.
  • This is a very, very weak Bronsted acid: Ka = 10^-50
  • pKa = 50

Use curved arrows to show where the electrons are moving to.

isomers are the same molecule that have the same atoms, but different connections between atoms.

Stereo-chemistry is the chemistry of shapes (how the molecule is arranged)