Q: A green laser pointer emits light at a wavelength of 532 nm. What is the frequency of this light?

$$5.6 \times 10$$^{14}$$\ \mathrm{s}^{-1}$$

Q: A red laser pointer emits at 650 nm. Calculate the energy of a single photon emitted by this laser.

$$3.1 \times 10$$^{-19}$$\ \mathrm{J}$$

Q: Using the Bohr model, what is the energy change ($$\Delta E) $$when an electron in hydrogen transitions from $$n=4 to$$ $$n=1$$?

$$2.04 \times 10$$^{-18}$$\ \mathrm{J}$$

Question 1

A green laser pointer emits light at a wavelength of 532 nm. What is the frequency of this light?

Accepted Answer

$$5.6 	imes 10$$^{14}$$\ \mathrm{s}^{-1}$$

Question 2

Which equation correctly relates the energy of a photon to its wavelength?

Accepted Answer

$$E = \dfrac{hc}{\lambda}$$

Question 3

A red laser pointer emits at 650 nm. Calculate the energy of a single photon emitted by this laser.

Accepted Answer

$$3.1 	imes 10$$^{-19}$$\ \mathrm{J}$$

Question 4

If the wavelength of light decreases, what happens to its frequency and energy?

Accepted Answer

Frequency increases and energy increases.

Question 5

Which of the following best describes the emission spectrum of hydrogen gas?

Accepted Answer

A line spectrum consisting of discrete wavelengths.

Question 6

Why does each element have a unique line spectrum?

Accepted Answer

Because each element has unique allowed energy levels for its electrons.

Question 7

Which transition in the hydrogen atom produces a photon with the shortest wavelength?

Accepted Answer

From $$n=4 to$$ $$n=1$$

Question 8

Using the Bohr model, what is the energy change ($$\Delta E) $$when an electron in hydrogen transitions from $$n=4 to$$ $$n=1$$?

Accepted Answer

$$2.04 	imes 10$$^{-18}$$\ \mathrm{J}$$

Question 9

A photon emitted during the $$n=4 to$$ $$n=1$$ transition in hydrogen has a wavelength of approximately:

Accepted Answer

$$97.2\ \mathrm{nm}$$

Question 10

In which region of the electromagnetic spectrum does the $$n=4 to$$ $$n=1$$ transition in hydrogen lie?

Accepted Answer

Ultraviolet

Question 11

According to the Bohr model, what happens when an electron in a hydrogen atom absorbs a photon?

Accepted Answer

It moves to a higher energy level.

Question 12

Which equation is used to calculate the wavelength of light emitted during an electron transition in hydrogen?

Accepted Answer

$$\dfrac{1}{\lambda} = R \left( \dfrac{1}{n_f^2$} - \dfrac{1}{n_i^2$} \right)$$

Question 13

What is the significance of the Rydberg constant in atomic spectra?

Accepted Answer

It allows calculation of the wavelengths of spectral lines in hydrogen.

Question 14

Which statement about the Bohr model is correct?

Accepted Answer

Electrons exist only in certain discrete energy levels.

Question 15

Why does the Bohr model only work for hydrogen and hydrogen-like atoms?

Accepted Answer

It assumes only one electron is present.

Question 16

A hydrogen atom is excited so its electron is in the $$n=4$$ state. Which transition will emit a photon in the visible region?

Accepted Answer

From $$n=4 to$$ $$n=2$$

Question 17

Which of the following is a limitation of the Bohr model?

Accepted Answer

It cannot explain atomic bonding and periodicity.

Question 18

If a photon is absorbed by a hydrogen atom, what must be true about the energy change ($$\Delta E$$)?

Accepted Answer

$$\Delta E is $$positive.

Question 19

Which of the following best explains why classical physics could not account for atomic stability?

Accepted Answer

Electrons would spiral into the nucleus due to continuous energy loss.

Question 20

A sample of hydrogen atoms is excited so that each electron is in the $$n=4$$ state. Which final state ($$n_f) $$transition would produce a photon with a wavelength of approximately $$480\ \mathrm{nm}$$?

Accepted Answer

$$n_f = 2$$

Atomic Spectra, Photon Energy, and the Bohr Model

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