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Molecular Models Activity. carbon tetrachloride methane water ethane ethyne dihydrogen monosulfide carbon dioxide. ammonia hydrogen monochloride trichloromethane urea propane butane nitrogen triiodide ( video ). supplies. B. :. N. :. :. O. Bonding and Shape of Molecules.
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Molecular Models Activity carbon tetrachloride methane water ethane ethyne dihydrogen monosulfide carbon dioxide ammonia hydrogen monochloride trichloromethane urea propane butane nitrogen triiodide (video) supplies
B : N : : O Bonding and Shape of Molecules Number of Bonds Number of Unshared Pairs Covalent Structure Shape Examples -Be- 0 0 0 1 2 2 3 4 3 2 Linear Trigonal planar Tetrahedral Pyramidal Bent BeCl2 BF3 CH4, SiCl4 NH3, PCl3 H2O, H2S, SCl2 C
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. Gilbert Lewis (not H, though) 3) Complete octets on exterior atoms - 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
Cl Cl Cl C Cl C Cl Cl Cl 109.5o Cl Carbon tetrachloride Tetrahedral geometry CCl4 Carbon tetrachloride – “carbon tet” had been used as dry cleaning solvent because of its extreme non-polarity.
H H C H H C H H H 109.5o H Methane Tetrahedral geometry Methane –The first member of the paraffin (alkane) hydrocarbons series. a.k.a. (marsh gas, CH4).
.. .. O H H Water d(-) SO2 Bent geometry d(+) Polar molecule
H H C C H H H H Ethane C = 1s22s22p2 ball-and-stick Lewis dot notation C2H4 molecular formula space-filling molecule
H H C C H H H H Ethane ball-and-stick Lewis dot notation C2H6 molecular formula space-filling molecule
6 electrons = triple bond C C C C H H H H H H H C C H Ethyne No octet each C “feels” 6 electrons Stable octet C2H2 C C each C “feels” 7 carbons Ethyne – a.k.a. “acetylene”
.. .. S H H Dihydrogen monosulfide SO2 Bent
C C O O O O Carbon dioxide O C O Linear geometry CO2
.. .. N H H H N H H 107o H N H H H Ammonia N H H NH3 H Trigonal Pyramidal geometry
: H : 1+ 1- N : N H H H H H Amino Acids – Functional Groups Amine Base Pair Carboxylic Acid R- COOH NH21- lose H+ H+ H+ NH21- NH3 NH41+ : N H H H H + amine ammonia ammonium ion
H Cl H H Cl Cl hydrogen chloride hydrochloric acid water Hydrogen monochloride HCl d(-) d(+) HCl(g) + H2O(l) HCl(aq) Polar molecule
H H H Cl Cl C C Cl Cl C Cl Cl Cl Cl 109.5o Cl Trichloromethane d(+) CHCl3 d(-) Tetrahedral geometry Polar molecule
O Urea NOT “di-urea” H H H H N N O C C N N H H H H CO(NH2)2 Urea – The first organic compound to be synthesized (Wohler, 1828).
H H H C C C H H H H H Propane H H H C C C H H H H H C3H8
H H H H C C C C H H H H H H Butane H H H H H - C - C - C - C - H H H H H H H H H C4H10 H C C C C H H H H H
.. N I I 107o I Nitrogen triiodide N I I I NI3 Trigonal Pyramidal geometry 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)
Cl H H C O Cl Cl C C C H H H Cl Cl Cl H H O H H Cl Cl S C C H C S Cl N I O H CO2 CH4 CCl4 C2H2 SH2 CHCl3 HCl
H H H H H H H C C C C C C C H H H H H H H H H H H N N I I H H H I
Decomposition of Nitrogen Triiodide N2 NI3 I2 2 NI3(s) N2(g) + 3 I2(g)
.. H N C H H H H 107o 109.5o H H O O O O O O O3, ozone .. O H .. 104.5o H CH4, methane NH3, ammonia H2O, water .. lone pair electrons
.. .. .. S O O O C O O S N F O O F F F F F F F F F F P S Xe F F F F F Cl F F F F F The VSEPR Model The Shapes of Some Simple ABn Molecules SO2 Linear Bent Trigonal planar Trigonal pyramidal AB6 T-shaped Square planar Trigonal bipyramidal Octahedral Brown, LeMay, Bursten, Chemistry The Central Science, 2000, page 305
Resources - Nomenclature Objectives General Chemistry PP Worksheet - binary cmpds: single charge cation Worksheet - binary compounds Worksheet - ions in chemical formulas Worksheet - ions in chemical compounds Worksheet - ionic cmpds: polyatomic ions w multiple-charge cation Worksheet - ionic formulas (binary, polyatomic, transition) Worksheet - empirical and molecular Worksheet - traditional system of nomenclature Worksheet - vocab (bonding) Worksheet - covalent binary cmpds: non-metal - non-metal Worksheet - ionic cmpds: polyatomic ions Activity - bondingpieces Worksheet - ionic binary cmpds: multiple charge cation Activity - molecular models Worksheet - errors in chemical formulas and nomenclature Activity - mole pattern Worksheet - oxidation numbers and ionic cmpds Textbook - questions Worksheet - names and formulas of cmpds Outline(general)