Q: Which of the following best describes the relationship between wavelength ($$\lambda) $$and frequency ($$\nu) of $$electromagnetic radiation?

They are inversely proportional: $$c = \lambda \nu$$

Q: A photon has a wavelength of $$4.00 \times 10$$^{-7}$$ m. What is its energy in joules? (h = 6.626$$ \times $$10^{-34} J$$·s, $$c = 3.00 \times 10^8$ m/s)

$$E = \dfrac{hc}{\lambda} = \dfrac{6.626 \times 10$$^{-34}$$ \times 3.00 \times 10^8$}{4.00 \times 10$$^{-7}$$} = 4.97 \times 10$$^{-19}$$ J

Question 1

Which of the following statements best explains why the emission spectrum of hydrogen contains only specific wavelengths?

Accepted Answer

Electrons in hydrogen atoms transition between quantized energy levels, emitting photons of specific energies.

Question 2

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

Accepted Answer

They are inversely proportional: $$c = \lambda 
u$$

Question 3

A photon has a wavelength of $$4.00 	imes 10$$^{-7}$$ m. What is its energy in joules? (h = 6.626$$ 	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}$$ 	imes 3.00 	imes 10^8$}{4.00 	imes 10$$^{-7}$$} = 4.97 	imes 10$$^{-19}$$ J

Question 4

Which of the following electron configurations represents a chloride ion ($$\mathrm{Cl^-}$$)?

Accepted Answer

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

Question 5

Which of the following elements has the highest first ionization energy?

Accepted Answer

Fluorine ($$\mathrm{F})$$

Question 6

Which statement correctly describes the trend in atomic radius across a period from left to right?

Accepted Answer

Atomic radius decreases due to increasing effective nuclear charge.

Question 7

Which of the following molecules is nonpolar despite having polar bonds?

Accepted Answer

Carbon dioxide ($$\mathrm{CO_2$})$$

Question 8

Which of the following best describes the bond in sodium chloride ($$\mathrm{NaCl}$$)?

Accepted Answer

An ionic bond formed by transfer of electrons from sodium to chlorine.

Question 9

Which of the following Lewis structures is correct for the nitrate ion ($$\mathrm{NO_3$^-}$$)?

Accepted Answer

Central N atom with three O atoms, one double bond, two single bonds, and one extra electron for the negative charge.

Question 10

Which molecule has a trigonal planar molecular geometry?

Accepted Answer

Boron trifluoride ($$\mathrm{BF_3$})$$

Question 11

Which of the following best explains why oxygen is paramagnetic?

Accepted Answer

Oxygen has unpaired electrons in its molecular orbitals.

Question 12

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties due to similar valence electron configurations.

Question 13

Which of the following ions is isoelectronic with neon ($$\mathrm{Ne}$$)?

Accepted Answer

$$\mathrm{Na^+}$$

Question 14

Which of the following best describes the concept of effective nuclear charge ($$Z_{eff}$$)?

Accepted Answer

The net positive charge experienced by an electron in a multi-electron atom.

Question 15

Which of the following molecules contains a triple bond?

Accepted Answer

Nitrogen ($$\mathrm{N_2$})$$

Question 16

Which of the following best explains why ionic compounds tend to have high melting points?

Accepted Answer

Strong electrostatic forces between oppositely charged ions require a large amount of energy to break.

Question 17

Which of the following best describes the hybridization of the central atom in methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

$$sp^3$$

Question 18

Which of the following molecules has a bond angle closest to $$109.5^\circ$$?

Accepted Answer

Methane ($$\mathrm{CH_4$})$$

Question 19

Which of the following best describes the difference between sigma ($$\sigma) $$and pi ($$\pi) $$bonds?

Accepted Answer

$$\sigma$$ bonds result from head-on overlap of orbitals, while $$\pi$$ bonds result from side-to-side overlap.

Question 20

A molecule has the formula $$\mathrm{C_2H_2}. $$What is the hybridization of each carbon atom?

Accepted Answer

$$sp$$

Chem 220: Exam 3 Review – Light, Electron Configurations, Periodic Trends, and Chemical Bonding

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