AP Chemistry Practice Test: Chs. 8 & 9 - Bonding

Flashcards covering chemical bonding concepts from Chapters 8 and 9, including Lewis structures, formal charge, resonance, bond enthalpies, VSEPR geometries, polarity, and orbital hybridization.

Based on the octet rule, what ion does magnesium most likely form?

$$Mg^{2+}$$

Based on the octet rule, what ion does phosphorus most likely form?

$$P^{3-}$$

Which ion among $B^{2+}$, $Be^{2+}$, $C^{2+}$, $N^{2-}$, and $Li^{2+}$ has a noble gas electron configuration?

$$Be^{2+}$$

What is the electron configuration of the phosphide ion ($P^{3-}$)?

$$[Ne]3s^2 3p^6$$

How many valence electrons do the halogens, alkali metals, and alkaline earth metals have, respectively?

$7$, $1$, and $2$

What is the definition of lattice energy?

The energy required to convert a mole of ionic solid into its constituent ions in the gas phase.

In which molecule among $H_3C-CH_3$, $H-C\equiv C-H$, $H_2C=C=CH_2$, $H_3C-CH_2-CH_3$, and $H_2C=CH_2$ is the carbon-carbon distance the shortest?

$$H-C\equiv C-H$$

Among the atoms $Ca$, $Rb$, $S$, $Cl$, and $Si$, which is the most electronegative?

$$Cl$$

What are the periodic trends for electronegativity across a period and down a group?

Electronegativity increases from left to right within a period and decreases from top to bottom within a group.

How many nonbonding electron pairs are on the central $As$ atom in the Lewis structure of $AsH_3$?

$$1$$

In the Lewis structure of $HCN$ (where $H$ is bonded to $C$), which atom has nonbonding electron pairs and how many does it have?

$N$ has $1$ nonbonding electron pair.

What does the Lewis structure of $N_2H_2$ show regarding nonbonding electron pairs on nitrogen?

Each nitrogen has one nonbonding electron pair.

Among the species (i) $PCl_3$, (ii) $CH_2Cl_2$, (iii) $HCN$, (iv) $C_2H_4$, and (v) $NH_3$, in which Lewis structure does the central atom have a non-zero formal charge?

None (all central atoms have a formal charge of $0$).

What is the formal charge on carbon in carbon dioxide ($O=C=O$)?

$$0$$

How many equivalent resonance forms can be drawn for $SO_2$ without expanding the octet on the sulfur atom?

$$2$$

For the oxyions (i) $NO_2^-$, (ii) $NO_3^-$, (iii) $SO_3^{2-}$, (iv) $SO_4^{2-}$, and (v) $BrO_3^-$, which central atoms cannot expand their octet?

(i) and (ii) (the central atom is nitrogen, which cannot expand its octet).

Which oxyion among (i) $NO_2^-$, (ii) $NO_3^-$, (iii) $SO_3^{2-}$, (iv) $SO_4^{2-}$, and (v) $BrO_3^-$ cannot be drawn without a non-zero formal charge on the central atom?

(ii) $NO_3^-$

For the oxyions (i) $NO_2^-$, (ii) $NO_3^-$, (iii) $SO_3^{2-}$, (iv) $SO_4^{2-}$, and (v) $BrO_3^-$, which can have Lewis structures drawn both with and without expanding the octet on the central atom?

(iii), (iv), and (v)

For the oxyions (i) $NO_2^-$, (ii) $NO_3^-$, (iii) $SO_3^{2-}$, (iv) $SO_4^{2-}$, and (v) $BrO_3^-$, which can have Lewis structures drawn with all formal charges being zero?

None (the sum of formal charges must equal the net charge of the ion).

Among $KrF_2$, $XeF_4$, $CF_4$, $ICl_4^-$, and $SF_4$, which molecule has a central atom that does not violate the octet rule?

$$CF_4$$

Given $CO(g) + 2H_2(g) \rightarrow CH_3OH(l)$ with $\Delta H_{rxn} = -128\,kJ$, and the bond energies $D(C\equiv O) = 1072\,kJ\,mol^{-1}$, $D(H-H) = 436\,kJ\,mol^{-1}$, $D(C-O) = 358\,kJ\,mol^{-1}$, and $D(O-H) = 463\,kJ\,mol^{-1}$, what is the calculated $C-H$ bond energy?

$$417\,kJ\,mol^{-1}$$

Why is the calculated $C-H$ bond energy ($417\,kJ\,mol^{-1}$) in the methanol formation reaction different from the tabulated value of $413\,kJ\,mol^{-1}$?

Tabulated bond energies are average values across many different molecules in the gas phase, whereas methanol is produced as a liquid ($CH_3OH(l)$) in this reaction, involving intermolecular forces and enthalpy of condensation.

Using the bond energies $D(C\equiv C) = 839\,kJ\,mol^{-1}$, $D(C=C) = 614\,kJ\,mol^{-1}$, $D(H-I) = 299\,kJ\,mol^{-1}$, $D(C-I) = 240\,kJ\,mol^{-1}$, and $D(C-H) = 413\,kJ\,mol^{-1}$, what is $\Delta H$ for the reaction $H-C\equiv C-H(g) + H-I(g) \rightarrow H_2C=CHI(g)$?

$$-129\,kJ$$

As the number of covalent bonds between two atoms increases, what happens to the distance between them and the strength of the bond?

The distance between the atoms decreases and the strength of the bond between them increases.

According to VSEPR theory, how are three electron domains arranged in the valence shell of an atom?

Trigonal planar

According to VSEPR theory, how are five electron domains arranged in the valence shell of an atom?

Trigonal bipyramidal

What are the electron-domain geometry and molecular geometry of iodine trichloride ($ICl_3$), respectively?

Trigonal bipyramidal and T-shaped

Among $CCl_4$, $XeF_4$, $ICl_3$, $XeF_2$, and $PH_3$, which species has a square planar molecular geometry?

$$XeF_4$$

What is the molecular geometry of the $H_3O^+$ ion?

Trigonal pyramidal

What is the molecular geometry of the $CS_2$ molecule?

Linear

What is the molecular geometry of the $PF_4^+$ ion?

Tetrahedral

Which species among $NCl_3$, $BCl_3$, $PH_3$, and $ClF_3$ has bond angles of $120^\circ$?

$$BCl_3$$

What is the molecular geometry of the $BrO_3^-$ ion?

Trigonal pyramidal

What is the molecular geometry of the left-most carbon atom in alanine ($CH_3CH(NH_2)COOH$)?

Tetrahedral

What are the approximate bond angles marked a ($sp^3$ carbon), b ($sp^2$ carbonyl carbon), and c ($sp^3$ oxygen) in alanine?

$109.5^\circ$, $120^\circ$, and $109.5^\circ$

How many unbonded electron pairs and bonded electron pairs are in the valence shell of the central iodine atom in $IF_5$?

$1$ unbonded electron pair and $5$ bonded electron pairs

Among $SbF_5$, $I_2$, $AsH_3$, $SF_6$, and $CH_4$, which molecule is polar?

$$AsH_3$$

Among $IF_3$, $BrCl_3$, $PBr_3$, $NF_3$, and $BF_3$, which molecule is nonpolar?

$$BF_3$$

What are the molecular geometry and polarity of the $CHF_3$ molecule?

Tetrahedral and polar

If the electron-domain geometry of a carbon-centered compound is tetrahedral, what is the hybridization of the central carbon atom?

$$sp^3$$

What is the hybridization of the carbon atom in carbon dioxide ($CO_2$)?

$$sp$$

What is the hybridization of the central atom in the $XeF_4$ molecule?

$$sp^3d^2$$

How many electron domains does the $sp^3d^2$ atomic hybrid orbital set accommodate?

$$6$$

What are the hybridizations of iodine in $IF_3$ and $IF_5$, respectively?

$sp^3d$ and $sp^3d^2$

What hybrid orbitals are produced by blending one $s$ atomic orbital and two $p$ atomic orbitals?

Three $sp^2$ hybrid orbitals

What are the angles between adjacent $sp^2$ hybrid orbitals?

$$120^\circ$$

What does a typical triple bond consist of in terms of sigma ($\sigma$) and pi ($\pi$) bonds?

One sigma ($\sigma$) and two pi ($\pi$) bonds

How many sigma ($\sigma$) bonds and pi ($\pi$) bonds are present in the molecule alanine ($CH_3CH(NH_2)COOH$)?

$12$ sigma ($\sigma$) bonds and $1$ pi ($\pi$) bond