Question 1

Which statement best describes the photoelectric effect as observed by Einstein?

Accepted Answer

Electrons are emitted from a metal surface only when the incident light exceeds a threshold frequency, regardless of its intensity.

Question 2

What does it mean when the energies of electrons in an atom are said to be quantized?

Accepted Answer

Electrons can only occupy specific energy levels, and not any value between them.

Question 3

Which of the following is the correct ground state electron configuration for magnesium ($$\mathrm{Mg}$$)?

Accepted Answer

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

Question 4

Which of the following best explains what happens inside an atom when it emits light?

Accepted Answer

An electron transitions from a higher energy level to a lower energy level, releasing a photon.

Question 5

Assign all four quantum numbers to a valence electron in the ground state of argon ($$\mathrm{Ar}). $$Which set is correct?

Accepted Answer

$$n=3,\ l=1,\ m_l=1,\ m_s=+\frac{1}{2}$$

Question 6

Which of the following ions has the same electron configuration as argon ($$\mathrm{Ar}$$)?

Accepted Answer

$$\mathrm{Cl^-}$$

Question 7

Which of the following elements is paramagnetic in its ground state?

Accepted Answer

Aluminum ($$\mathrm{Al})$$

Question 8

Which atom has a higher first ionization energy, potassium ($$\mathrm{K}) or $$lithium ($$\mathrm{Li}$$), and why?

Accepted Answer

Lithium, because its valence electron is closer to the nucleus and experiences greater attraction.

Question 9

Which atom is larger: sodium ($$\mathrm{Na}) or $$phosphorus ($$\mathrm{P}$$)? Why?

Accepted Answer

Sodium, because it is further to the left on the periodic table and has fewer protons pulling on its electrons.

Question 10

Which is larger: sodium atom ($$\mathrm{Na}) or $$sodium ion ($$\mathrm{Na^+}$$)? Why?

Accepted Answer

Sodium atom, because losing an electron reduces electron-electron repulsion and the ion has a smaller radius.

Question 11

Which has a larger first ionization energy: nitrogen ($$\mathrm{N}) or $$oxygen ($$\mathrm{O}$$)? Does this fit the general trend?

Accepted Answer

Nitrogen, and this does not fit the general trend because nitrogen has a half-filled $$2p$$ subshell, which is more stable.

Question 12

Which of the following best describes why metals tend to lose electrons and non-metals gain electrons?

Accepted Answer

Metals have low ionization energies and large atomic radii, making it easier to lose electrons, while non-metals have high ionization energies and small radii, favoring electron gain.

Question 13

Why are the second electron affinity values for both sulfur and oxygen endothermic?

Accepted Answer

Adding a second electron to an already negatively charged ion requires energy to overcome repulsion between electrons.

Question 14

Which of the following best explains why some bonds are ionic and some are covalent?

Accepted Answer

Ionic bonds form when there is a large difference in electronegativity between atoms, while covalent bonds form when atoms have similar electronegativities.

Question 15

Which molecule has a net dipole moment: $$\mathrm{$$SeO_2$$} or$$ $$\mathrm{$$SeO_3$$}$$?

Accepted Answer

$$\mathrm{$$SeO_2$$}$$, because its bent geometry leads to a net dipole moment.

Question 16

Compare the lattice energies for magnesium hydroxide ($$\mathrm{Mg(OH)_2}) $$and magnesium oxide ($$\mathrm{MgO}). $$Which is favored and why?

Accepted Answer

$$\mathrm{MgO}$$ has a higher lattice energy because it contains ions with higher charges ($$\mathrm{Mg$$^{2+}$$}$$ and $$\mathrm{O$$^{2-}$$}$$), leading to stronger electrostatic attraction.

Question 17

True or false: Lone pair electrons tend to increase the bond angle on the central atom. Explain.

Accepted Answer

False. Lone pair electrons cause greater repulsion, which decreases the bond angle between atoms.

General Chemistry II Exam 2 Review – Step-by-Step Study Guidance

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