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Bell Work Bonding / Chap 8 Reading Is Due Today! Pick Up Note Sheet Pick Up & Complete Bell Work
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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.
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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.
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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
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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
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Coulombs law: charge & distance More shared e- Shorter bond length = strength More charge = strength Coulomb’s Still At Play HOW?
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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
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Pi (π) & Sigma (σ) Bonds Double Bond = sigma & pi Triple Bond = sigma & 2 pi
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Bond Order Bond order = number of bonds
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Electronegativity determines level of attraction for shared e- Similar values (0.0 - 0.4) = equal sharing = nonpolar bond Bond Properties – Polarity
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Differing Values (0.5 – 2.0) = unequal sharing = polar bond Creates unequal distribution of e- in the molecule Bond Properties – Polarity
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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
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Bond Properties – Ionic Vs. Covalent
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Learning Goal student can use Lewis diagrams and VSEPR to predict the molecular geometry, hybridization and polarity of molecules
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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
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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
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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
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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
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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)
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Bond angles change slightly with increased repelling Double, triple bonds hold more e-, ↑ bond angle Lone pairs, ↓ bond angle VSEPR & MOLECULAR GEOMETRY (SHAPE)
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VSEPR VSEPR VSEPR & MOLECULAR GEOMETRY (SHAPE)
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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
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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
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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?
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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
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Homework Finish Lab Report & Simulation
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