Q: A green traffic signal emits light with a frequency of $$5.75 \times 10$$^{14}$$ Hz. What is the wavelength (in nm) of this light? (Speed of light c = 3.00$$ \times $$10^8 m/s)$$

$$3.00 \times 10^8$ / 5.75 \times 10$$^{14}$$ = 5.22 \times 10$$^{-7}$$ m = 522$ nm

Q: What is the energy of a photon emitted by a light source with a wavelength of $$652 nm$$? ($$h = 6.626 \times 10$$^{-34}$$ J·s, c = 3.00$$ \times $$10^8 m/s)$$

$$E = \dfrac{hc}{\lambda} = \dfrac{6.626 \times 10$$^{-34}$$ \times 3.00 \times 10^8$}{652 \times 10$$^{-9}$$} = 3.05 \times 10$$^{-19}$$ J

Question 1

Which of the following statements best describes the concept of quantization as it applies to electrons in atoms?

Accepted Answer

Electrons can only occupy certain discrete energy levels within an atom.

Question 2

A green traffic signal emits light with a frequency of $$5.75 	imes 10$$^{14}$$ Hz. What is the wavelength (in nm) of this light? (Speed of light c = 3.00$$ 	imes $$10^8 m/s)$$

Accepted Answer

$$3.00 	imes 10^8$ / 5.75 	imes 10$$^{14}$$ = 5.22 	imes 10$$^{-7}$$ m = 522$ nm

Question 3

Which transition in a hydrogen atom emits the largest amount of energy?

Accepted Answer

$$n = 3 \rightarrow n = 1$$

Question 4

What is the energy of a photon emitted by a light source with a wavelength of $$652 nm$$? ($$h = 6.626 	imes 10$$^{-34}$$ J·s, c = 3.00$$ 	imes $$10^8 m/s)$$

Accepted Answer

$$E = \dfrac{hc}{\lambda} = \dfrac{6.626 	imes 10$$^{-34}$$ 	imes 3.00 	imes 10^8$}{652 	imes 10$$^{-9}$$} = 3.05 	imes 10$$^{-19}$$ J

Question 5

Which of the following best explains why each element has a unique atomic emission spectrum?

Accepted Answer

Each element has a unique arrangement of energy levels for its electrons.

Question 6

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

Accepted Answer

No electrons are ejected, regardless of the light's intensity.

Question 7

Calculate the de Broglie wavelength of a car with mass $$1150 kg $$traveling at $$24.6 m/s$$. ($$h = 6.626 	imes 10$$^{-34}$$ kg·m^2$/s)

Accepted Answer

$$2.34 	imes 10$$^{-38}$$ m

Question 8

Which of the following sets of quantum numbers is forbidden for an electron in an atom? Explain why.

Accepted Answer

{5, 0, -1, +1/2}

Question 9

Which quantum number defines the shape of an atomic orbital?

Accepted Answer

Angular-momentum quantum number ($$l)$$

Question 10

What is the maximum number of electrons that can occupy the $$3d$$ subshell?

Accepted Answer

10

Question 11

Which of the following electron configurations represents the ground state of sodium (Na)?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^1$$

Question 12

Which principle states that no two electrons in an atom can have the same set of four quantum numbers?

Accepted Answer

Pauli Exclusion Principle

Question 13

Which of the following best describes Hund’s Rule?

Accepted Answer

Electrons occupy degenerate orbitals singly before pairing up.

Question 14

What is the effective nuclear charge ($$Z_{eff}) $$experienced by an electron in a multielectron atom?

Accepted Answer

$$Z_{eff} = Z_{actual} -$$ electron shielding

Question 15

Which of the following elements has the largest atomic radius based on periodic trends?

Accepted Answer

Cesium (Cs)

Question 16

Which of the following statements about the Heisenberg Uncertainty Principle is correct?

Accepted Answer

It is impossible to know both the exact position and momentum of an electron simultaneously.

Question 17

Which of the following is the correct set of quantum numbers for a 4p orbital?

Accepted Answer

$$n = 4, l = 1, m_l = -1, 0, 1$$

Question 18

Which of the following best describes the wave-particle duality of matter?

Accepted Answer

Matter exhibits both wave-like and particle-like properties.

Question 19

Which of the following electron configurations is anomalous due to increased stability from a half-filled or fully-filled d subshell?

Accepted Answer

[Ar] $$4s^1$$ $$3d^5$$

Question 20

Which of the following best explains why atomic radius decreases across a period from left to right?

Accepted Answer

The effective nuclear charge increases, pulling electrons closer to the nucleus.

Periodicity and the Electronic Structure of Atoms: Quantum Mechanics, Atomic Orbitals, and Periodic Properties

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