Q: If the wavelength of an emission line is $$500\ \mathrm{nm}$$, what is the energy of the photon emitted? (Use $$h = 6.626 \times 10$$^{-34}$$\ \mathrm{J\cdot s}$$ and $$c = 3.00 \times 10^8$\ \mathrm{m/s})$$

$$E = 3.98 \times 10$$^{-19}$$\ \mathrm{J}$$

Question 1

Which process is responsible for the emission lines observed in the atomic emission spectrum?

Accepted Answer

Movement of electrons from higher energy states to lower energy states in atoms.

Question 2

A scientist observes the emission spectrum of an unknown gas and notices a bright line at a wavelength of $$400\ \mathrm{nm}. $$What does this indicate about the energy transition in the atom?

Accepted Answer

An electron moved from a higher energy state to a lower energy state, releasing a photon with energy $$E = \dfrac{hc}{\lambda}.$$

Question 3

Which of the following best describes the role of a prism in the observation of an emission spectrum?

Accepted Answer

It separates the emitted light into its component wavelengths.

Question 4

Given the emission spectrum of helium with lines labeled A, B, C, D, and E, which line corresponds to the highest energy transition?

Accepted Answer

Line D

Question 5

If the wavelength of an emission line is $$500\ \mathrm{nm}$$, what is the energy of the photon emitted? (Use $$h = 6.626 	imes 10$$^{-34}$$\ \mathrm{J\cdot s}$$ and $$c = 3.00 	imes 10^8$\ \mathrm{m/s})$$

Accepted Answer

$$E = 3.98 	imes 10$$^{-19}$$\ \mathrm{J}$$

Question 6

Which of the following statements about emission spectra is FALSE?

Accepted Answer

Emission spectra are continuous for all elements.

Question 7

Why do different elements produce different emission spectra?

Accepted Answer

Because each element has a unique set of energy levels for its electrons.

Question 8

A student observes that the emission spectrum of hydrogen contains a line at $$656\ \mathrm{nm}. $$What does this line represent?

Accepted Answer

An electron transition from a higher to a lower energy state, specifically from $$n=3 to$$ $$n=2.$$

Question 9

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

Accepted Answer

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

Question 10

In a laboratory, a student observes that the emission spectrum of sodium contains two closely spaced yellow lines. What is the best explanation for this observation?

Accepted Answer

Sodium atoms have two closely spaced energy levels involved in the electron transitions.

Question 11

Which of the following best explains why emission spectra are useful in astronomy?

Accepted Answer

They allow astronomers to identify the elements present in distant stars and galaxies.

Question 12

A photon is emitted when an electron in a hydrogen atom transitions from $$n=4 to$$ $$n=2. $$Which of the following is true about the energy of the emitted photon?

Accepted Answer

It is equal to the energy difference between the $$n=4$$ and $$n=2$$ levels.

Emission Spectrum and Electron Transitions in Atoms

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