Bell Work  Bonding / Chap 8 Reading Is Due Today!  Pick Up Note Sheet  Pick Up & Complete Bell Work

BW – Lewis Diagrams Provide Lewis Structure For Each Molecule Below Determine which has resonance and provide those structuresDetermine which has shortest bond length & why. CO, carbon monoxide has the shortest bond length because it contains a triple bond instead of double or single bonds. In triple bonds more e- are being shared creating a stronger electrostatic attraction and less lone pairs are present to create repulsions so the bonding atoms are able to get closer together making the bond length shorter.

BW – Formal Charge Determine the formal charge for each element in both structures Determine which structure best represents formic acid & why Structure #1, because its formula charges are all zero and lower than that of structure #2 so structure #1 is more stable than structure #2 making it the most likely form formic acid would be found in.

Learning Goal  student can predict the type of bonding between two atoms based on their position on the periodic table and electronegativity values  student can rank and justify bond polarity in molecules  student can apply Coulomb’s law to describe the interactions of ions / atoms

more bonding e- = less repulsion o Atoms are closer o Bond length is shorter more bonding e- = more attraction o Bond strength increases o Bond movement decreases Bond Properties

Coulombs law: charge & distance More shared e- Shorter bond length = strength More charge = strength Coulomb’s Still At Play HOW?

Sigma (σ) = Single Orbitals overlap “head to head” e- meet between atoms center Pi (  ) = Double & Triple Orbitals meet “side to side” e- meet above and below atoms center Also contain a sigma bond Bond Properties

Pi (π) & Sigma (σ) Bonds Double Bond = sigma & pi Triple Bond = sigma & 2 pi

Bond Order Bond order = number of bonds

Electronegativity determines level of attraction for shared e- Similar values ( ) = equal sharing = nonpolar bond Bond Properties – Polarity

Differing Values (0.5 – 2.0) = unequal sharing = polar bond Creates unequal distribution of e- in the molecule Bond Properties – Polarity

Molecule is neutral (no e- lost or gained) Uneven distribution creates areas of slight charge (dipoles) One side is Slightly positive Slightly negative Distribution gradually changes, forming a dipole moment And polar covalent molecule Bond Properties – Polarity simulation

Bond Properties – Ionic Vs. Covalent

Learning Goal  student can use Lewis diagrams and VSEPR to predict the molecular geometry, hybridization and polarity of molecules

Goal  Orbitals of Equal Energy & Distance From Nucleus  Orbitals (e-) maximum distance apart, to stabilize repelling Molecular Structure Quantum Orbitals ARE NOT of Equal Energy & Distance Quantum Orbitals ARE NOT of Equal Energy & Distance

Orbitals blend together to create a new set of orbitals that are of equal energy & equal distance from nucleus Hybrid gives equal energy originally unequal energy Hybrid orbitals

Goal: Maximum separation between orbitals Based on number of orbitals needed Number of orbitals needed will vary Lone pairs need an orbital Shared e- (any type of bonding) need an orbital Hybrid orbitals

Determining hybridization Orbitals Needed  THIS IS NOT THE NUMBER OF BONDS IN THE MOLECULE!!!  EACH UNSHARED PAIR = ONE  EACH SHARED REGION / OVERLAP = ONE Double & Triple Bonds ONLY COUNT AS ONE, they are in the same orbital

Valence Shell Electron Pair Repulsion  Each atom in a molecule will achieve a geometry that minimizes the repulsion between electrons in the valence shell of that atom  Hybridization determines electron geometry  Bonded atoms vs. lone pairs determine molecular geometry  Bonded atoms contribute to shape  Lone e- pairs subtract from electron geometry VSEPR & MOLECULAR GEOMETRY (SHAPE)

Bond angles change slightly with increased repelling  Double, triple bonds hold more e-, ↑ bond angle  Lone pairs, ↓ bond angle VSEPR & MOLECULAR GEOMETRY (SHAPE)

 VSEPR VSEPR VSEPR & MOLECULAR GEOMETRY (SHAPE)

Polarity Dipole Moment: molecule with a charge distribution due to unequal e- density shown by using Dipole (  + or  - ) indicates the fractional charge because overall molecule is neutral Polar bond ≠ Polar Molecule (Dipoles Cancel) No Net Dipole Moment

No lone pairs = usually nonpolar, bonds will cancel Lone pairs = usually polar, bonds won’t cancel Must look at electronegativity, especially if atom type varies Polar Molecules

Carbon chains = organic molecules What is the Hybridization E- geometry Molecular geo For each “C” atom? What is the Hybridization E- geometry Molecular geo For each “C” atom?

Tues = 7:50am o Lab Notebook Due o Simulation Due o Metallic Bonding o Bonding & VSEPR Practice Thurs = 7:50 am o KMT o Lab Prep o Cont. Practice Mon = 7:30am o Pre Lab Due o Practice Due o Lab Upcoming

Homework Finish Lab Report & Simulation