Final Exam Review

Conceptual Reminders: Waves/Blackbody Radiation Energy

Example

A lamp rated at 40.0 J/sec emits violet light of wavelength 422 nm. What is the energy of the photons? How many photons of violet light can the lamp generate in 2.0 sec?

Applicable concepts/equations

Etotal = Ephoton* # photons

𝐸=h𝑐l

Wave Particle Duality

Things light does:• Reflection/Refraction

• Diffraction

• Polarization

• Interference****

• Photoelectric effect***

Can a wave do this? Can a Particle do this?

yes

yes

yes

yes

no

no

****Things we discussed in this course.

yes no

no yes

Wave/Particle Duality Reviewhttps://www.youtube.com/watch?v=DfPeprQ7oGc

Double Split Experiment

Does this show that light has wavelike or particle like

properties? Why?

What would the results look like if they had particle like

properties?

Wave-like: It creates an interference pattern.

Two bright lines behind the splits no interference pattern.

Things light does:• Reflection/Refraction

• Diffraction

• Polarization

• Interference***

• Photoelectric effect***

Can a wave do this? Can a Particle do this?

yes

yes

yes

yes

no

no

****Things we discussed in this course.

Wave/Particle Duality ReviewPhotoelectric EffectDoes this show that light has wavelike or particle like properties? Why? What would the results look like if they had only wave-like properties?

What is the effect of increasing the intensity of a laser of a frequency less than the threshold frequency? 

 What is the effect of increasing the intensity of a laser of a frequency greater the threshold frequency?

http://phet.colorado.edu/en/simulation/photoelectric

Example Problem:• Calculate the frequency of an electron ejected from the surface of a copper sheet that

has a work function of 7.53 × 10-19 J if the electron has a kinetic energy of 1.3*10-19 J. Draw the graph of what an experiment would look like if the frequency of the incident light started below the threshold frequency and was slowly increased. Write the equation of the resulting graph.

Wavefunction and probability density. • Explain the difference between a wavefunction and a probability density.

Give the symbol for each in your explanation and also state what sign (positive or negative) each is allowed to be. Draw a picture of the first and second wavefunction and probability densities for the particle in a box.

• How do wavefunctions and probability densities relate to orbitals in hydrogen atoms? In other atoms?

......Lets look at the path we took to get to atoms

How did we get to the pictures of orbitals we have now….

Particle in a box

(1d)

Particle in a box (2/3D)

Hydrogen Atom

Multi electron atoms= many

types of approximation,

no exact solutions

Schrodinger equation solutions

Didn’t coverSubject of Current research: We saw result, of appoximations

Electron Configurations

Electron Configurations: Ground states

• Give the ground electron configuration for Sb.

• Give the ground electron configuration for neutral Copper.

• Give ground electron configuration for +1 copper.

Electron Configurations: Excited states

• Ground state: Sb.

• Ground state for neutral Copper.

For each of the previous neutral electron configurations, give an excited state.

Keep same number of electrons, move at least one up in energy: Many many many correct answers.

Quantum numbers

What is the quantum numbers for the highest energy electrons in phosphorous?

How many orbitals and electrons are in the n=3 and n=2 energy levels.

n=3

n=2

Periodic Trends

Effective Nuclear Charge

Ele

ctro

neg

ati

vit

y

ElectronegativityIonization EnergyElectron Affinity

Atomic Radius

Ion

izati

on

En

erg

y

Ele

ctro

n A

ffin

ity

Ato

mic

Rad

ius

Summary

Questions: Periodic Trends• Why is atomic radius the reverse of the other trends?• This is not the answer and is not worth any points:

• “Because all the other ones go up and to the right and atomic radius goes down and to the left”.

Effective Nuclear Charge

Ele

ctro

neg

ati

vit

y

ElectronegativityIonization EnergyElectron Affinity

Atomic Radius

Ion

izati

on

En

erg

y

Ele

ctro

n A

ffin

ity

Ato

mic

Rad

ius

Exceptions?

Periodic trends exceptions: Write the electron configurations for C, N, and O. Place in order of increasing ionization energy, increasing electron affinity and increasing electronegativity. For each characteristic, do these follow the trend? Why or why not?

Wrong Answer 1: All: C, N, O

Yes

Because the trend goes up and to the right.

Wrong Answer 2: Variety of wrong/right answers

NoBecause the trend goes up and to the right. But hydrogen is half filled.

• You are on cash cab and you are asked where the d-block exceptions to electron affinity are. First you curse me for not having that be required exam knowledge, but then you think back on the p block exceptions and your logic used above. What do you guess for the d-block exceptions in order to claim your prize?Hint: what is the p block exceptions to electron affinity?

Hint: What would be the equivalent of that with the dblock?

Ionization Energy:

I1 I2 I3 I4

Element 1

0.605

1.110 1.45

5.10

Element 2

0.203

3.215 3.89

4.42

Which group do these elements belong to?

First is always smallest,The “jump” indicates

stable configuration

Other topics in Quantum Mechanics

Why do we see the sun as different colors?

Which lights depicted in this diagram are emitted, which are scattered.

What causes the events depicted by the blue arrows in the atmosphere.

MO Theory

2p

• Draw the MO diagram for C2. Write the electron configuration. Is it para or diamagnetic and state the bond order.• Describe the difference between the bonding

and antibonding orbitals (energy levels, energy levels in relation to starting orbitals, and shapes).

E

C N

CN

Bonding, shape and structure

Examples

Draw the lewis and line structure of CH3COO-: Tell me everything about everything about it!• Steric coordination number of each

element• Hybridization of all applicable

elements• All bond angles• Is it polar? • What are all the formal charges• What overlapping orbitals form

each bond. (next slide)

Line Structure Example• Draw the line structure of HOCH2CHCHCH2COOH. What is the

hybridization of each atom.

ResonanceIf given two resonance structures of equal stability, how is the sigma and pi bonding electrons shared amongst the atoms in the molecule? How does this affect bond order? How does this affect the location of formal charges? Draw an example of a molecule with resonance to help explain.

Gas Law

Conceptual questions. • In which of the two conditions shown

is the gas more ideal?(assume same number of particles/temperature in each container).

• In which of the two conditions shown is the pressure higher? (assume same number of particles in each container).

CH3OH can be synthesized by the reaction shown. What volume of H2 gas (in L), at 748 mmHg and 86 oC, is required to synthesize 25.8 g CH3OH?

Grams product

Volume Reacta

nt

moles product

moles reactant

s

conversion conversion Ideal gas law

Part 2: If the reaction is known to only be 70.0% efficient (aka has a 70% yield) what volume is required (at the same conditions)?