Molecular Models Activity carbon tetrachloride ammonia methane hydrogen

Molecular Models Activity carbon tetrachloride ammonia methane hydrogen monochloride water trichloromethane urea ethyne propane dihydrogen monosulfide butane carbon dioxide nitrogen triiodide (video) supplies

Bonding and Shape of Molecules Number of Unshared Pairs Covalent Structure Shape Examples -Be- Linear Be. Cl 2 Trigonal planar BF 3 2 0 3 0 4 0 C Tetrahedral CH 4, Si. Cl 4 3 1 : Number of Bonds Pyramidal NH 3, PCl 3 2 2 Bent H 2 O, H 2 S, SCl 2 B : N O:

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) - no unpaired electrons (free radicals) 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

Carbon tetrachloride Cl Cl CCl 4 Cl Cl 109. 5 o Cl Tetrahedral geometry Carbon tetrachloride – “carbon tet” had been used as dry cleaning solvent because of its extreme non-polarity.

Methane H H CH H H C H H 109. 5 o H Tetrahedral geometry Methane –The first member of the paraffin (alkane) hydrocarbons series. a. k. a. (marsh gas, CH 4).

Water d(-) . . Bent geometry . . SO 2 O H H d(+) Polar molecule

Ethane C = 1 s 22 p 2 H H H C CH H H Lewis dot notation ball-and-stick C 2 H 4 molecular formula space-filling molecule

Ethane H H H C CH H H Lewis dot notation ball-and-stick C 2 H 6 molecular formula space-filling molecule

Ethyne No octet each C “feels” 6 electrons H C CH C 2 H 2 H C CH each C “feels” 7 carbons Ethyne – a. k. a. “acetylene” 6 electrons = triple bond H C CH Stable octet

Dihydrogen monosulfide. . SO 2 S H H Bent

Carbon dioxide O CO 2 O C Linear geometry O O C O

Ammonia. . NH 3 N HH H N H H H Trigonal Pyramidal geometry N H H 107 o H

Amino Acids – Functional Groups Amine Base Pair Carboxylic Acid R- COOH NH 21 lose H+ NH 21 - NH 3 H+ NH 41+ H : N H : : : 1 - N N H amine H H 1+ H ammonia H H H ammonium ion

Hydrogen monochloride H Cl HCl d(+) d(-) HCl(g) + H 2 O(l) HCl(aq) hydrogen chloride Polar molecule water hydrochloric acid

Trichloromethane d(+) H Cl Cl CHCl 3 H C Cl Cl 109. 5 o Cl Tetrahedral geometry H Cl Cl d(-) Polar molecule

Urea NOT “di-urea” H H N O C N H H CO(NH 2)2 Urea – The first organic compound to be synthesized (Wohler, 1828).

Propane H H C C CH H C 3 H 8 H H C H H

Butane H H H C CH H H C 4 H 10 H H H-C-C-H H H C H H C H H

Nitrogen triiodide. . N I I I NI 3 N I 107 o I I Trigonal Pyramidal geometry Video clip: (slow motion) detonation of NI 3

Supplies q q q q 15 black 8 green 1 yellow 4 blue 4 red 42 hydrogen 67 bonds (carbon) (chlorine and iodine) (sulfur) (oxygen) (nitrogen) (hydrogen) (bonds)

C Cl S I Cl Cl Cl H H CCl 4 CH 4 HCl CHCl 3 H O C O H Cl Cl HC CH C 2 H 2 O N CO 2 S H H SH 2

H H H C CH H H N H HH H H C C CH H N I I I

Decomposition of Nitrogen Triiodide

Decomposition of Nitrogen Triiodide NI 3 2 NI 3(s) N 2 I 2 N 2(g) + 3 I 2(g)

. . C N O H 109. 5 o H H CH 4, methane lone pair electrons H 107 o H . . H H H NH 3, ammonia 104. 5 o H 2 O, water . . O O O 3, ozone H O O

The VSEPR Model The Shapes of Some Simple ABn Molecules . . O C . . SO 2 . . O N S O O Linear O Bent F S O F F O Trigonal planar Trigonal pyramidal AB 6 F F F Cl F F T-shaped F F F Square planar Brown, Le. May, Bursten, Chemistry The Central Science, 2000, page 305 F F P Xe F F F S F F F Trigonal bipyramidal Octahedral