Q: A dental hygienist uses x-rays with a wavelength of $$0.50\ \text{\AA} to $$take radiographs. What is the frequency ($$\nu) of $$these x-rays? ($$c = 3.00 \times 10^8$\ \text{m/s})$$

$$6.0 \times 10$$^{18}$$\ \text{Hz}$$

Q: Calculate the energy of a single photon of microwave radiation with a wavelength of $$1.20\ \text{cm}$$. ($$h = 6.63 \times 10$$^{-34}$$\ \text{J} \cdot \text{s}$$, $$c = 3.00 \times 10^8$\ \text{m/s})$$

$$1.66 \times 10$$^{-23}$$\ \text{J}$$

Q: Order the following species from smallest to largest radius: $$\text{K}^+$$, $$\text{Na}^+$$, $$\text{K}.$$

Smallest $$\text{Na}^+ \u003c \text{K}^+ \u003c \text{K}$$ Largest

Question 1

Which of the following statements best describes the relationship between wavelength ($$\lambda) $$and frequency ($$
u) $$for electromagnetic radiation?

Accepted Answer

Wavelength and frequency are inversely proportional, as described by $$c = \lambda 
u.$$

Question 2

A dental hygienist uses x-rays with a wavelength of $$0.50\ 	ext{\AA} to $$take radiographs. What is the frequency ($$
u) of $$these x-rays? ($$c = 3.00 	imes 10^8$\ 	ext{m/s})$$

Accepted Answer

$$6.0 	imes 10$$^{18}$$\ 	ext{Hz}$$

Question 3

Which experiment provided evidence that light behaves as a stream of particles (photons) rather than only as a wave?

Accepted Answer

The photoelectric effect

Question 4

According to the photoelectric effect, what happens when light of frequency lower than the threshold frequency ($$
u_0$) shines on a metal surface?

Accepted Answer

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

Question 5

Calculate the energy of a single photon of microwave radiation with a wavelength of $$1.20\ 	ext{cm}$$. ($$h = 6.63 	imes 10$$^{-34}$$\ 	ext{J} \cdot 	ext{s}$$, $$c = 3.00 	imes 10^8$\ 	ext{m/s})$$

Accepted Answer

$$1.66 	imes 10$$^{-23}$$\ 	ext{J}$$

Question 6

Which of the following best explains why each element produces a unique line spectrum?

Accepted Answer

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

Question 7

Using 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, and the atom relaxes to a lower energy state.

Question 8

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number ($$\ell)$$

Question 9

Which of the following sets of quantum numbers is NOT allowed for an electron in an atom?

Accepted Answer

$$n=1,\ \ell=1,\ m_\ell=0,\ m_s=+\frac{1}{2}$$

Question 10

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 11

Which of the following electron configurations represents a transition metal in its ground state?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^6$$\ $$4s^2$$\ $$3d^5$$

Question 12

Which of the following ions is isoelectronic with argon ($$	ext{Ar}$$)?

Accepted Answer

$$	ext{Cl}^-$$

Question 13

Order the following species from smallest to largest radius: $$	ext{K}^+$$, $$	ext{Na}^+$$, $$	ext{K}.$$

Accepted Answer

Smallest $$	ext{Na}^+ \u003c 	ext{K}^+ \u003c 	ext{K}$$ Largest

Question 14

Which element has the highest first ionization energy?

Accepted Answer

Fluorine (F)

Question 15

Which of the following best describes the trend in atomic radius across a period from left to right?

Accepted Answer

Atomic radius decreases due to increasing effective nuclear charge ($$Z_{	ext{eff}}).$$

Question 16

Which of the following electron configurations is an example of an anomalous configuration due to increased stability of half-filled or fully-filled $$d$$ orbitals?

Accepted Answer

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

Question 17

Which of the following statements about electron affinity is correct?

Accepted Answer

Electron affinity generally becomes more negative across a period, reaching a maximum (most negative) for halogens.

Question 18

Which quantum number(s) describe the orientation of an orbital in space?

Accepted Answer

Magnetic quantum number ($$m_\ell)$$

Question 19

Which of the following best describes Hund's Rule?

Accepted Answer

Electrons occupy degenerate orbitals singly before pairing.

Chapter 3: Electronic Structure of the Atom: Waves, Photons, and Quantum Theory

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