Question 1

Which of the following best explains why the second ionization energy of sodium ($$\mathrm{Na}) is $$much greater than its first ionization energy?

Accepted Answer

The second electron is removed from a stable noble gas configuration, which requires significantly more energy.

Question 2

Which of the following compounds contains both ionic and covalent bonds?

Accepted Answer

$$\mathrm{Na_2SO_4}$$

Question 3

Given the following mass percentages for a compound: 40.0% C, 6.7% H, and 53.3% O, what is the empirical formula?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 4

Which of the following best describes why an ionic bond forms between sodium and chlorine?

Accepted Answer

Because the transfer of an electron from sodium to chlorine results in a lower energy state due to electrostatic attraction, as described by Coulomb's Law.

Question 5

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

Accepted Answer

$$\mathrm{CO_2$}$$

Question 6

What is the correct name for the compound $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

Iron(III) chloride

Question 7

Which of the following statements about resonance structures is TRUE?

Accepted Answer

Resonance structures show that the actual molecule is a hybrid of all possible structures, with delocalized electrons.

Question 8

Which of the following best explains why ozone ($$\mathrm{O_3$}) $$can absorb UV-B radiation while $$\mathrm{O_2$}$$ cannot?

Accepted Answer

Ozone has resonance structures that allow for delocalized electrons, which can absorb UV-B radiation.

Question 9

What is the molecular geometry of $$\mathrm{NH_3$}$$ according to VSEPR theory?

Accepted Answer

Trigonal pyramidal

Question 10

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

Accepted Answer

A $$\sigma$$ bond results from end-to-end overlap of orbitals, while a $$\pi$$ bond results from side-to-side overlap.

Question 11

Which of the following is the correct formula for ammonium sulfate?

Accepted Answer

$$\mathrm{(NH_4$)_2SO_4}$$

Question 12

A molecule has the Lewis structure shown below. What is the formal charge on the central atom?

$$\mathrm{[O=N^+-O^-]}$$

Accepted Answer

+1

Question 13

Which of the following best describes why bond formation is exothermic?

Accepted Answer

Bond formation releases energy because the system moves to a lower potential energy state.

Question 14

Which of the following molecules contains a triple bond?

Accepted Answer

$$\mathrm{N_2$}$$

Question 15

What is the hybridization of the central carbon atom in $$\mathrm{CO_2$}$$?

Accepted Answer

$$\mathrm{sp}$$

Question 16

Which of the following best explains why $$\mathrm{He_2$}$$ does not exist as a stable molecule, according to molecular orbital theory?

Accepted Answer

The bond order is zero because the number of electrons in bonding and antibonding orbitals is equal.

Question 17

A sample contains 18.0 g of water ($$\mathrm{H_2O}). $$How many moles of water are present?

Accepted Answer

1.00 mol

Question 18

Which of the following best describes the shape and orientation of $$\mathrm{sp^3$}$$ hybrid orbitals?

Accepted Answer

Tetrahedral, 109.5° angles

Question 19

Which of the following is a correct statement about cis- and trans- isomers?

Accepted Answer

Cis- and trans- isomers are possible due to restricted rotation around double bonds.

Question 20

Which of the following best describes the role of constructive interference in chemical bonding?

Accepted Answer

Constructive interference between atomic orbitals increases electron density between nuclei, stabilizing the bond.

Study Guide: Atomic Properties, Chemical Bonding, and Molecular Structure

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