Q: The work function ($$\phi) of a $$metal is the minimum energy required to eject an electron from its surface. If the work function of a metal is $$1.72\ \mathrm{eV}$$, what is the threshold wavelength ($$\lambda_{\text{threshold}}) $$required to just eject an electron? Use $$E = \dfrac{hc}{\lambda}$$, $$h = 6.626 \times 10$$^{-34}$$\ \mathrm{J\cdot s}$$, $$c = 3.00 \times 10^8$\ \mathrm{m/s}$$, and $$1\ \mathrm{eV} = 1.602 \times 10$$^{-19}$$\ \mathrm{J}.$$

$$\lambda_{\text{threshold}} = 721\ \mathrm{nm}$$

Q: In the Bohr model, what is the energy of the electron in the ground state ($$n=1) of a $$hydrogen atom? Use $$R_H = 2.179 \times 10$$^{-18}$$\ \mathrm{J}.$$

$$E_1 = -2.179$$ \times $$10^{-18}$$\ \mathrm{J}$$

Question 1

Which experiment provided evidence that energy is quantized and could not be explained by classical physics?

Accepted Answer

The blackbody radiation experiment

Question 2

According to the photoelectric effect, what happens when light of a certain minimum frequency shines on a metal surface?

Accepted Answer

Electrons are ejected only if the light's frequency is above a threshold value

Question 3

The work function ($$\phi) of a $$metal is the minimum energy required to eject an electron from its surface. If the work function of a metal is $$1.72\ \mathrm{eV}$$, what is the threshold wavelength ($$\lambda_{	ext{threshold}}) $$required to just eject an electron? Use $$E = \dfrac{hc}{\lambda}$$, $$h = 6.626 	imes 10$$^{-34}$$\ \mathrm{J\cdot s}$$, $$c = 3.00 	imes 10^8$\ \mathrm{m/s}$$, and $$1\ \mathrm{eV} = 1.602 	imes 10$$^{-19}$$\ \mathrm{J}.$$

Accepted Answer

$$\lambda_{	ext{threshold}} = 721\ \mathrm{nm}$$

Question 4

Which of the following best explains why the emission spectrum of hydrogen consists of discrete lines rather than a continuous spectrum?

Accepted Answer

Electrons in hydrogen atoms can only occupy certain allowed energy levels

Question 5

According to the Bohr model, what happens when an electron in a hydrogen atom transitions from $$n=4 to$$ $$n=2$$?

Accepted Answer

A photon is emitted with energy equal to the difference between the two levels

Question 6

Which series in the hydrogen atomic spectrum corresponds to electron transitions ending at $$n=2$$?

Accepted Answer

Balmer series

Question 7

A hydrogen atom emits light at a wavelength of $$486.1\ \mathrm{nm}. To $$which transition does this correspond?

Accepted Answer

$$n=4 \rightarrow n=2$$

Question 8

Which of the following statements about blackbody radiation is correct?

Accepted Answer

The peak wavelength of emitted radiation shifts to shorter wavelengths as temperature increases

Question 9

Which equation correctly gives the energy of a photon?

Accepted Answer

$$E = hf$$

Question 10

In the Bohr model, what is the energy of the electron in the ground state ($$n=1) of a $$hydrogen atom? Use $$R_H = 2.179 	imes 10$$^{-18}$$\ \mathrm{J}.$$

Accepted Answer

$$E_1 = -2.179$$ 	imes $$10^{-18}$$\ \mathrm{J}$$

Question 11

Which of the following best describes the meaning of $$n = \infty in $$the Bohr model?

Accepted Answer

The electron is completely removed from the atom (ionized)

Question 12

Which of the following transitions in the hydrogen atom would emit a photon with the highest energy?

Accepted Answer

$$n=2 \rightarrow n=1$$

Question 13

Which of the following is a real-world application of atomic spectra?

Accepted Answer

Identifying elements in distant stars using their emission lines

Question 14

If a photon with energy less than the work function of a metal strikes the metal surface, what will happen?

Accepted Answer

No electrons will be ejected

Question 15

Which of the following best explains why the Bohr model was necessary to explain the hydrogen atom's spectrum?

Accepted Answer

Classical physics predicted that electrons would spiral into the nucleus

Question 16

Which of the following transitions in the hydrogen atom corresponds to the Lyman series?

Accepted Answer

Transitions ending at $$n=1$$

Question 17

A sodium lamp emits a characteristic yellow color. This is due to:

Accepted Answer

A specific electron transition between energy levels in sodium atoms

Question 18

Which of the following best describes the relationship between temperature and the peak wavelength of blackbody radiation?

Accepted Answer

As temperature increases, the peak wavelength shifts to shorter wavelengths

Question 19

Which of the following is NOT a prediction of the Bohr model for hydrogen-like atoms?

Accepted Answer

Electrons lose energy continuously as they orbit the nucleus

Lec 3 notes chem

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