MAGNETIC FIELD? MORE ON BONDING THEORIES UNIT 3 Day 5 What are we - - PowerPoint PPT Presentation

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Nov 22, 2023 390 likes •631 views

Sparks CH301 WHY DOES A FROG FLOAT IN A MAGNETIC FIELD? MORE ON BONDING THEORIES UNIT 3 Day 5 What are we going to learn today? EXPLORE MOLECULAR ORBITAL THEORY Quiz: CLICKER QUESTION Given a tetrahedral electronic geometry, which of the

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Sparks CH301 WHY DOES A FROG FLOAT IN A MAGNETIC FIELD? MORE ON BONDING THEORIES UNIT 3 Day 5

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What are we going to learn today?

EXPLORE MOLECULAR ORBITAL THEORY

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Quiz: CLICKER QUESTION

Given a tetrahedral electronic geometry, which of the following hybridizations is possible? a) sp b) sp2 c) sp3 d) sp3d

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Ethanol Diatomic Oxygen

EXPLAIN THE VB HYBRIDIZATION IN ETHANOL

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ANOTHER PHYSCIAL MODEL VB MO Valence Bond Molecular Orbital localized de-localized

IT’S ABOUT THE MOLECULE NOT THE BOND……. http://www.youtube.com/watch?v=yJs5ENtilIo

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What is bond strength and bond length in H2?

How can we get that? Quantum mechanics, oribitals for the whole molecule and energies for all electrons – what distance? For the whole molecule – not just atomic orbital!

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E

BONDING AND ANTIBONDING ORBITALS

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Combine atomic orbitals, sometimes you get

higher and sometimes you get lower energy

Remember electrons have wave functions
Constructive and destructive interference
Two possibilities

IDEAS ABOUT MO

http://winter.group.shef.ac.uk/orbitron/MOs/H2/1s1s-sigma/index.html

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Wavefunctions, like waves, can INTERFERE Two main results: CONSTRUCTIVE and DESTRUCTIVE

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and 1s 1s

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COMPARE MO TO VB FOR H2

Very similar because the bond is the molecule If the molecule is stable, then electrons in MO are lower in energy than in AO. Number of MO in molecule = total number of AO in atoms

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What does the electron configuration for He2 look like?

HOW MANY ELECTRONS? WHERE DO THEY GO? BOND ORDER = ½(# BONDING - # ANTIBONDING)

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POLL: CLICKER QUESTION

What is the bond order for H2

+?

CAN YOU DRAW THE LEWIS STRUCTURE?

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What different ways can p-orbitals overlap?

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NOTE: ANOTHER SET EXISTS AT RIGHT ANGLES TO THESE

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Here are the MO’s for N2 The highest energy electrons are in what molecular orbital?

A. σ2s
B. σ*2s
C. σ2p
D. σ*2p
E. π*2p

POLL: CLICKER QUESTION IS IT DIAMAGNETIC OR PARAMAGNETIC?

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Identify all valence orbitals
Use each matching pair of valence shell atomic orbitals to

build a bonding and an antibonding MO and draw the resulting MO energy level diagram

Note the total number of electrons present in the valence

shells of the two atoms, adjust for ions

Accommodate the electrons in the MO according to the

building up principle

To determine the bond order (BO), subtract the number of

electrons in the antibonding orbitals from the number in bonding orbitals and divide the result by two. BO = ½ (N – N*)

Rules for Electron Configuration and Bond Order Calculation

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MOs can combine AO on dif atoms Diagram for CN-

HOMO LUMO Bond Order? DIAMAGNETIC OR PARAMAGNETIC?

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What if its not a diatomic? Methane

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Typical MO for organic molecule

Almost always diamagnetic HOMO/LUMO Energy gap Light absorption

Dyes – homo lumo gap is the color that is absorbed, gaps as a function of structure

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