Question 1

Which of the following statements best describes the difference between absorption and emission in the context of electronic transitions in a hydrogen atom?

Accepted Answer

Absorption occurs when an electron moves from a lower to a higher energy level, while emission occurs when an electron moves from a higher to a lower energy level.

Question 2

Given the following electron configuration: $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^4$$, which element does this configuration represent, and how many valence electrons does it have?

Accepted Answer

Sulfur (S), 6 valence electrons

Question 3

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

Accepted Answer

Effective nuclear charge increases, pulling electrons closer to the nucleus.

Question 4

Calculate the wavelength (in nm) of light emitted when an electron in a hydrogen atom transitions from $$n=4 to$$ $$n=2. $$Use $$R_H = 1.097 	imes 10^7$ \ \mathrm{m}^{-1}.$$

Accepted Answer

$$486 \ \mathrm{nm}$$

Question 5

Which of the following quantum numbers is NOT allowed for an electron in a 3d orbital?

Accepted Answer

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

Question 6

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

Accepted Answer

Neon (Ne)

Question 7

A sample of sodium metal reacts violently with water, producing hydrogen gas and sodium hydroxide. Which type of chemical bond is broken in sodium metal during this reaction?

Accepted Answer

Metallic bond

Question 8

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

Accepted Answer

Electron affinity generally becomes more negative (increases in magnitude).

Question 9

Which of the following molecules has a linear geometry according to VSEPR theory?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 10

Which of the following statements about Hund's Rule is correct?

Accepted Answer

Electrons fill degenerate orbitals singly before pairing up.

Question 11

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

Accepted Answer

$$\mathrm{Cl^-}$$

Question 12

Which of the following best explains why fluorine has a higher electronegativity than chlorine?

Accepted Answer

Fluorine has a smaller atomic radius and a higher effective nuclear charge.

Question 13

Which of the following is the correct ground-state electron configuration for chromium ($$\mathrm{Cr}$$, atomic number 24)?

Accepted Answer

$$[\mathrm{Ar}]\ 4s^1$\ 3d^5$

Question 14

Which of the following best describes the effect of increasing ionic radius on lattice energy, assuming all other factors are constant?

Accepted Answer

Lattice energy decreases as ionic radius increases.

Question 15

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

Accepted Answer

A structure with three resonance forms, each with a double bond to one oxygen and single bonds to the other two, with formal charges minimized.

Question 16

Which of the following best describes the relationship between wavelength ($$\lambda) $$and momentum ($$p) $$for a particle according to the de Broglie equation?

Accepted Answer

$$\lambda = \frac{h}{p}$$

Question 17

Which of the following statements about the photoelectric effect is correct?

Accepted Answer

Electrons are ejected from a metal surface only if the incident light has a frequency above a certain threshold.

Question 18

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

Metals have delocalized electrons that can move freely throughout the lattice.

Question 19

Which of the following is the correct formula for calculating the formal charge of an atom in a Lewis structure?

Accepted Answer

$$	ext{Formal charge} = 	ext{Valence electrons} - (	ext{Nonbonding electrons} + \frac{1}{2} 	imes 	ext{Bonding electrons})$$

Question 20

Which of the following best describes the trend in metallic character down a group in the periodic table?

Accepted Answer

Metallic character increases down a group.

General Chemistry Study Guide: Atomic Structure, Periodicity, and Chemical Bonding

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