molecular models activity ammonia hydrogen monochloride trichloromethane urea propane butane...
TRANSCRIPT
Molecular Models Activity
ammonia
hydrogen monochloride
trichloromethane
urea
propane
butane
nitrogen triiodide (video)
carbon tetrachloride
methane
water
ethane
ethyne
dihydrogen monosulfide
carbon dioxide
supplies
Bonding and Shape of Molecules
Number of Bonds
Number of Unshared Pairs Shape Examples
2
3
4
3
2
0
0
0
1
2
Linear
Trigonal planar
Tetrahedral
Pyramidal
Bent
BeCl2
BF3
CH4, SiCl4
NH3, PCl3
H2O, H2S, SCl2
-Be-
B
C
N
:
O
:
:
CovalentStructure
Lewis Structures
1) Count up total number of valence electrons
2) Connect all atoms with single bonds
- “multiple” atoms usually on outside
- “single” atoms usually in center;
C always in center,
H always on outside.
3) Complete octets on exterior atoms (not H, though)
4) Check
- valence electrons match with Step 1
- all atoms (except H) have an octet; if not, try multiple bonds
- any extra electrons? Put on central atom
- no unpaired electrons (free radicals)
Carbon tetrachloride
C ClClCl
Cl
CCl4
C109.5o
Cl
ClClCl
Carbon tetrachloride – “carbon tet” had been used as dry cleaning solventbecause of its extreme non-polarity.
Tetrahedral geometry
Methane
CHH
HH
C109.5o
H
HHH
Methane –The first member of the paraffin (alkane) hydrocarbons series. a.k.a. (marsh gas, CH4).
Tetrahedral geometry
Ethane
CH
CHH
HHH
space-filling molecule
ball-and-stickLewis dot notation
C2H4
molecular formula
C = 1s22s22p2
Ethyne
CCH H CCH H
No octet
Stable octet
6 electrons = triple bond
CCH H
C2H2
CCH H
each C “feels” 6 electrons
each C “feels” 7 carbons
Ethyne – a.k.a. “acetylene”
Amino Acids – Functional Groups
Amine Carboxylic AcidBase Pair
NH21- R- COOH
NH3NH21- NH4
1+
amine ammonia ammonium ion
NH
HH
:
NH
HH
H : 1+
NH
H
:
1-
:
H+ lose H+
Hydrogen monochloride
H ClHCl
H Cl
d(-)d(+)
H Cl
Polar molecule
HCl(g) + H2O(l) HCl(aq)
hydrogenchloride
water hydrochloric acid
Trichloromethane
C ClClCl
H
CHCl3
C109.5o
H
ClClCl
C ClClCl
H
d(-)
d(+)
Polar molecule
Tetrahedral geometry
Urea
CON HH
NH H
CON HH
NH H
CO(NH2)2
NOT “di-urea”
Urea – The first organic compound to be synthesized (Wohler, 1828).
Nitrogen triiodide
NI II N
107o III
..
NI3
TrigonalPyramidalgeometry
Video clip:
(slow motion)
detonation of NI3
Supplies
15 black (carbon) 8 green (chlorine and iodine) 1 yellow (sulfur) 4 blue (oxygen) 4 red (nitrogen) 42 hydrogen (hydrogen) 67 bonds (bonds)
C109.5o
H
HHH
N107o HH
H
..
O104.5o H
H
..
..
CH4, methane NH3, ammonia H2O, water
..
O
O
O
lone pairelectrons
OOO
O3, ozone
......
The VSEPR Model
O OC
Linear
The Shapes of Some Simple ABn Molecules
O OS
BentO O
S
O
Trigonalplanar
FF
F
N
Trigonalpyramidal
T-shaped Squareplanar
F FCl
F
F F
Xe
F FF
F
FP
F
F
Trigonalbipyramidal
Octahedral
FF
F
S
F
F
F
AB6
SO2
Brown, LeMay, Bursten, Chemistry The Central Science, 2000, page 305