Q: An AM radio station broadcasts at 960 kHz. What is the wavelength (in meters) of this radiation? (Speed of light $$c = 3.00 \times 10^8$ m/s)

$$\lambda = \frac{c}{\nu} = \frac{3.00 \times 10^8$}{9.60 \times 10^5$} = 312.5 m$$

Q: How many photons are in one mole of light?

$$6.022 \times 10$$^{23}$$ photons

Question 1

Which of the following statements best explains why electrons in atoms are described using quantum numbers?

Accepted Answer

Quantum numbers describe the most probable regions where electrons are found, based on the wave nature of electrons.

Question 2

Which equation relates the energy of a photon to its frequency?

Accepted Answer

$$E = h 
u$$

Question 3

A nitrogen gas laser emits light with a wavelength of 337 nm and a pulse contains 3.83 mJ of energy. Which of the following steps is NOT necessary to calculate the number of photons in the pulse?

Accepted Answer

Multiply the energy of a single photon by Avogadro's number.

Question 4

Arrange the colors of a traffic signal (red, yellow, green) from lowest to highest energy based on their wavelengths.

Accepted Answer

Red \u003c Yellow \u003c Green

Question 5

An AM radio station broadcasts at 960 kHz. What is the wavelength (in meters) of this radiation? (Speed of light $$c = 3.00 	imes 10^8$ m/s)

Accepted Answer

$$\lambda = \frac{c}{
u} = \frac{3.00 	imes 10^8$}{9.60 	imes 10^5$} = 312.5 m$$

Question 6

Which experiment demonstrated the wave nature of light and matter?

Accepted Answer

The double-slit experiment

Question 7

The photoelectric effect provided evidence for which property of light?

Accepted Answer

Light behaves as a particle

Question 8

If light with an energy of 625 kJ/mol is shined on a sodium surface with a threshold wavelength of 182 nm, will an electron be ejected? (Use $$E = \frac{hc}{\lambda}$$ and $$h = 6.626 	imes 10$$^{-34}$$ J·s, c = 3.00$$ 	imes $$10^8 m/s$$, $$N_A = 6.022 	imes 10$$^{23}$$ mol$$^{-1}$$)

Accepted Answer

No, because the energy per photon is less than the threshold energy.

Question 9

Why do atoms emit line spectra instead of continuous spectra when heated?

Accepted Answer

Electrons in atoms can only occupy specific energy levels, so only certain photon energies are emitted.

Question 10

What is happening inside an atom when it emits light?

Accepted Answer

An electron falls from a higher energy level to a lower energy level, emitting a photon.

Question 11

Which set of quantum numbers is possible for a 3d orbital?

Accepted Answer

$$n = 3, \ l = 2, \ m_l = 0$$

Question 12

Which transition in the hydrogen atom emission diagram corresponds to the emission of the highest energy photon?

Accepted Answer

Transition d: $$n=5 \rightarrow n=1$$

Question 13

Which of the following best describes the difference between a 2s and a 4s orbital?

Accepted Answer

A 4s orbital is larger and has more nodes than a 2s orbital.

Question 14

How many photons are in one mole of light?

Accepted Answer

$$6.022 	imes 10$$^{23}$$ photons

Question 15

Which quantum number determines the shape of an orbital?

Accepted Answer

The angular momentum quantum number $$l$$

Study Guide: Electronic Structure of Atoms (CHEM 1251)

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