Q1. On the wave below, label the wavelength, frequency, and amplitude.

Background

Topic: Properties of Waves

This question tests your understanding of the basic characteristics of waves, which are essential for describing the behavior of electrons and light in quantum mechanics.

Key Terms:

• Wavelength (\lambda): The distance between two consecutive peaks (or troughs) of the wave.

• Frequency (\nu): The number of wave cycles that pass a given point per second.

• Amplitude: The height of the wave from the center line to the peak (or trough).

Step-by-Step Guidance

1. Identify the repeating pattern in the wave. The wavelength (\lambda) is the horizontal distance between two adjacent peaks.

2. The amplitude is the vertical distance from the center of the wave to a peak (or trough).

3. Frequency (\nu) is not directly shown in the diagram, but it relates to how many wavelengths pass a point per second.

4. Label these features on the diagram, using arrows or lines to indicate each property.

Try labeling the diagram before revealing the answer!

Q2. The energy of the light wave above can be determined using what two equations? These equations provide you an energy in what units?

Background

Topic: Energy of Light Waves

This question tests your knowledge of how to calculate the energy of light using its frequency or wavelength.

Key Formulas:

Where:

• = energy (in joules, J)

• = Planck's constant ( J·s)

• = frequency (in Hz)

• = speed of light ( m/s)

• = wavelength (in meters)

Step-by-Step Guidance

1. Recall that energy can be calculated using frequency: .

2. Alternatively, energy can be calculated using wavelength: .

3. Both equations give energy in units of joules (J).

4. Think about which equation to use based on whether you are given frequency or wavelength.

Try writing out the equations and units before revealing the answer!

Q3. 1 mole = __________ photons

Background

Topic: Avogadro's Number and Photons

This question tests your understanding of the relationship between moles and the number of particles (photons, in this case).

Key Term:

• Avogadro's Number (): particles per mole

Step-by-Step Guidance

1. Recall that 1 mole of any substance contains Avogadro's number of particles.

2. For photons, 1 mole means photons.

3. Write this value in the blank.

Try filling in the blank before revealing the answer!

Q4. Without performing any calculations, arrange the lights on a traffic signal from lowest to highest energy.

Background

Topic: Relationship Between Wavelength and Energy

This question tests your understanding of how the energy of light relates to its wavelength.

Key Concept:

• Energy is inversely proportional to wavelength:

Step-by-Step Guidance

1. List the wavelengths: Red (750 nm), Yellow (580 nm), Green (500 nm).

2. Recall that shorter wavelength means higher energy.

3. Arrange the colors from longest to shortest wavelength.

4. Now, arrange them from lowest to highest energy based on their wavelengths.

Try arranging the colors before revealing the answer!

Q5. A nitrogen gas laser pulse with a wavelength of 337 nm contains 3.83 mJ of energy. How many photons does it contain?

Background

Topic: Calculating Number of Photons

This question tests your ability to use energy and wavelength to determine the number of photons in a sample.

Key Formulas:

Where:

• = Planck's constant ( J·s)

• = speed of light ( m/s)

• = wavelength (in meters)

• Total energy = 3.83 mJ = J

Step-by-Step Guidance

1. Convert the wavelength from nm to meters: m.

2. Calculate the energy of one photon using .

3. Divide the total energy by the energy per photon to find the number of photons.

4. Set up the calculation, but stop before computing the final value.

Try setting up the calculation before revealing the answer!

Q6. An AM radio station broadcasts at 960 kHz.

Background

Topic: Electromagnetic Radiation Calculations

This question tests your ability to convert frequency to wavelength and calculate photon energy.

Key Formulas:

Where:

• = frequency (960 kHz = Hz)

• = speed of light ( m/s)

• = Planck's constant ( J·s)

• = Avogadro's number ()

Step-by-Step Guidance

1. Convert the frequency to Hz: Hz.

2. Calculate the wavelength using .

3. Calculate the energy of one photon using .

4. Calculate the energy of one mole of photons using .

5. Set up each calculation, but stop before computing the final values.

Try setting up the calculations before revealing the answer!

Q7. What experiment taught us that light (and matter) behaves as a wave? Draw a diagram of this experiment.

Background

Topic: Wave-Particle Duality

This question tests your knowledge of the experiment that demonstrated the wave nature of light and matter.

Key Concept:

• The double-slit experiment shows interference patterns, indicating wave behavior.

Step-by-Step Guidance

1. Recall the double-slit experiment, where light passes through two slits and creates an interference pattern.

2. Draw a diagram showing the setup: a light source, two slits, and a screen with alternating bright and dark bands.

3. Explain how the pattern demonstrates wave behavior.

Try drawing the diagram and explaining before revealing the answer!

Q8. What effect taught us that light (and matter) behaves as a particle?

Background

Topic: Photoelectric Effect

This question tests your knowledge of the experiment that demonstrated the particle nature of light.

Key Concept:

• The photoelectric effect shows that light can eject electrons from a metal surface, behaving as particles (photons).

Step-by-Step Guidance

1. Recall the photoelectric effect experiment, where light shines on a metal and electrons are ejected.

2. Draw a diagram showing a light source, metal surface, and ejected electrons.

3. Explain how the effect demonstrates particle behavior.

Try drawing the diagram and explaining before revealing the answer!

Q9. Let’s say I shine light with an energy of 625 kJ/mol on a sodium surface with a threshold wavelength of 182 nm. Will an electron be ejected? Justify your answer.

Background

Topic: Photoelectric Effect and Threshold Energy

This question tests your ability to compare the energy of incident light to the threshold energy required to eject electrons.

Key Formulas:

• Compare to

Step-by-Step Guidance

1. Convert the threshold wavelength to energy using .

2. Compare the energy of the incident light (625 kJ/mol) to the threshold energy.

3. If , electrons will be ejected.

4. Set up the comparison, but stop before making the final conclusion.

Try setting up the comparison before revealing the answer!

Q10. When an atom, such as lithium, is heated in a flame, it emits a line spectrum:

Background

Topic: Atomic Spectra

This question tests your understanding of the difference between line and continuous spectra, and why atoms emit line spectra.

Key Terms:

• Line Spectrum: Discrete wavelengths emitted by atoms.

• Continuous Spectrum: All wavelengths emitted, as in a rainbow.

Step-by-Step Guidance

1. Recall that a line spectrum consists of specific wavelengths, while a continuous spectrum includes all wavelengths.

2. Atoms emit line spectra because electrons transition between discrete energy levels.

3. Explain the process inside the atom: electrons absorb energy, move to higher levels, then emit photons as they return to lower levels.

4. Match each wavelength in the emission spectrum to the correct transition using the provided diagrams.

Try matching the transitions before revealing the answer!

Q11. The basics of what we know about electrons were developed using the hydrogen atom as a model. When we have multielectron atoms, we must use Schrodinger’s equation to provide us with information about the electrons. When you solve this monstrosity, three values (called quantum numbers) result:

Background

Topic: Quantum Numbers

This question tests your understanding of the quantum numbers that describe electron orbitals.

Key Terms:

• Principal quantum number (n): Energy level

• Angular momentum quantum number (l): Shape of orbital

• Magnetic quantum number (m_l): Orientation of orbital

Step-by-Step Guidance

1. Recall the three quantum numbers: n, l, m_l.

2. Each quantum number has allowed values depending on the orbital.

3. Think about how these numbers describe the location and shape of electrons in atoms.

Try listing the quantum numbers before revealing the answer!

Q12. Consider a 3d orbital. Provide three quantum numbers for this orbital and draw what it would look like.

Background

Topic: Quantum Numbers and Orbital Shapes

This question tests your ability to assign quantum numbers and visualize orbital shapes.

Key Terms:

• For a 3d orbital: n = 3, l = 2, m_l = -2, -1, 0, 1, or 2

Step-by-Step Guidance

1. Assign n = 3 (third energy level).

2. Assign l = 2 (d orbital).

3. Choose one value for m_l (e.g., 0).

4. Draw or visualize the shape of a d orbital (complex, often cloverleaf).

Try assigning the quantum numbers and visualizing the shape before revealing the answer!

Q13. Consider a 2p orbital. Provide three quantum numbers for this orbital and draw what it would look like.

Background

Topic: Quantum Numbers and Orbital Shapes

This question tests your ability to assign quantum numbers and visualize orbital shapes.

Key Terms:

• For a 2p orbital: n = 2, l = 1, m_l = -1, 0, or 1

Step-by-Step Guidance

1. Assign n = 2 (second energy level).

2. Assign l = 1 (p orbital).

3. Choose one value for m_l (e.g., 0).

4. Draw or visualize the shape of a p orbital (dumbbell-shaped).

Try assigning the quantum numbers and visualizing the shape before revealing the answer!

Q14. Consider a 2s and a 4s orbital. Provide three quantum numbers for each orbital and draw what they would look like.

Background

Topic: Quantum Numbers and Orbital Shapes

This question tests your ability to assign quantum numbers and visualize s orbital shapes.

Key Terms:

• For a 2s orbital: n = 2, l = 0, m_l = 0

• For a 4s orbital: n = 4, l = 0, m_l = 0

Step-by-Step Guidance

1. Assign n = 2, l = 0, m_l = 0 for 2s.

2. Assign n = 4, l = 0, m_l = 0 for 4s.

3. Draw or visualize the shape of s orbitals (spherical).

Try assigning the quantum numbers and visualizing the shapes before revealing the answer!