General Chemistry: Molecular Structure, Bonding Theories, Gases, and Intermolecular Forces

Comprehensive practice flashcards in fill-in-the-blank style covering molecular structure, VSEPR geometries, hybrid orbitals, Molecular Orbital Theory, gas laws, Kinetic-Molecular Theory, intermolecular forces, and phase equilibria.

According to the Valence Shell Electron Pair Repulsion (VSEPR) model, electron regions repel each other and arrange themselves as far apart as possible to minimize __________ repulsions.

electron-electron

In VSEPR theory, a single bond, a double bond, a triple bond, and a lone pair each count as __________ electron region(s).

$$1$$

A central atom with the VSEPR formula $AX_2$ has $2$ electron regions, $0$ lone pairs, a bond angle of $180^\circ$, and a __________ molecular geometry.

linear

A central atom with $3$ electron regions and $1$ lone pair ($AX_2E$), such as $ONF$, adopts an electron geometry that is trigonal planar and a molecular geometry that is __________.

bent

Ammonia ($NH_3$) has $4$ electron regions and $1$ lone pair ($AX_3E$), producing a __________ molecular geometry with bond angles of $<109^\circ$.

trigonal pyramidal

Elements in the third period and below can accommodate more than eight electrons around them, forming an __________ octet.

expanded

Phosphorus pentachloride ($PCl_5$) has $5$ electron regions around the central atom and adopts a __________ molecular shape.

trigonal bipyramidal

Sulfur hexafluoride ($SF_6$) has $6$ electron regions around the central sulfur atom and adopts an __________ molecular shape.

octahedral

In the structure of nepetalactone, the shape about the carbon labeled $\alpha$ (which has $4$ single bonds and no lone pairs) is __________.

tetrahedral

When overlapping atomic orbitals approach along the internuclear axis with electron density located directly between the nuclei, a __________ bond forms.

$$\sigma$$

A pi ($\pi$) bond forms when atomic orbitals overlap above and below the internuclear axis, creating a plane of zero electron density termed a __________.

nodal plane

Every single covalent bond consists of exactly $1$ $\sigma$ bond, a double bond consists of $1\,\sigma$ and $1\,\pi$ bond, and a triple bond consists of $1\,\sigma$ and __________ $\pi$ bond(s).

$$2$$

The acrylonitrile molecule shown contains exactly __________ $\sigma$ bonds and $3\,\pi$ bonds.

$$6$$

A central atom with $2$ electron regions hybridizes one $2s$ and one $2p$ orbital to produce two __________ hybrid orbitals oriented at an angle of $180^\circ$.

$$sp$$

An atom that is $sp^2$ hybridized mixes three atomic orbitals to yield three hybrid orbitals with $33\%$ s-character and $66\%$ p-character, leaving __________ unhybridized pure p orbital(s).

$$1$$

In Valence Bond Theory, hybrid orbitals are used to form $\sigma$ bonds and hold lone pairs, while unhybridized pure p orbitals are used to form __________ bonds.

$$\pi$$

In the structure of citalopram, the atom labeled with letter __________ is $sp^3$ hybridized.

B

By convention in Molecular Orbital (MO) Theory representations, the red color denotes an orbital wavefunction with a positive algebraic sign, while the blue color denotes a __________ algebraic sign.

negative

In Molecular Orbital Theory, the formula to calculate bond order (BO) is $\text{BO} = \frac{(\text{\# } e^- \text{ in bonding MOs} - \text{\# } e^- \text{ in antibonding MOs})}{\_\_\_\_\_\_\_\_\_\_}$.

$$2$$

The diatomic species $He_2$ has $2$ electrons in a bonding $\sigma$ orbital and $2$ electrons in an antibonding $\sigma^*$ orbital, giving a bond order of __________ and explaining why it cannot exist.

$$0$$

Based on the provided drawing, the interaction that represents a $\pi^*$ (pi antibonding) molecular orbital is labeled with the letter __________.

C

While Lewis structures incorrectly predict $O_2$ to be diamagnetic, Molecular Orbital Theory correctly predicts that $O_2$ is __________ due to two unpaired electrons residing in the $\pi^*(2p)$ orbitals.

paramagnetic

In MO Theory, HOMO stands for Highest Occupied Molecular Orbital, while LUMO stands for __________.

Lowest Unoccupied Molecular Orbital

As the extent of conjugation and delocalization in a molecule increases, the energy gap between the HOMO and the LUMO becomes __________.

smaller

Standard atmospheric pressure of $1\,atm$ is equivalent to $760\,mm\,Hg$, $760\,torr$, or __________ $Pa$.

$$101,325$$

At sea level, atmospheric pressure supports a mercury column of $760\,mm$ ($\sim 2.5\,ft$) in a barometer, whereas it would support a water column of __________ $mm$ ($33.7\,feet$).

$$10,260$$

In an open-end manometer with an atmospheric pressure of $766\,mm\,Hg$, if the trapped gas pushes less than the atmosphere by $\Delta H = 25\,mm$, the pressure of the trapped gas is __________ $mm\,Hg$.

$$741$$

Boyle's Law states that at constant temperature and amount of gas, volume is __________ proportional to pressure.

inversely

Charles' Law states that volume is directly proportional to absolute temperature; extrapolating this relationship to zero volume establishes absolute zero at __________ $^\circ\text{C}$.

$$-273.15$$

According to Dalton's Law of Partial Pressures, the partial pressure of gas component X can be calculated as $P_X = [X]RT$, where $[X]$ represents the __________ concentration of the gas in $mol\,L^{-1}$.

molar

In dry air, the most abundant component by volume is nitrogen ($N_2$) at $78.08\%$ ($\sim 0.78\,atm$), followed by oxygen ($O_2$) at __________ $\%$ ($\sim 0.21\,atm$).

$$20.95$$

The approximate average thermal energy of particles in a system is related to temperature by the equation $\Delta E_{thermal} \approx RT$, which at $25^\circ\text{C}$ evaluates to approximately __________ $kJ\,mol^{-1}$.

$$2.5$$

A solid state exists when thermal energy is __________ interaction energy.

less than

Intermolecular forces typically have bond strengths between $0\text{--}40\,kJ\,mol^{-1}$, whereas covalent intramolecular bonds have typical strengths around __________ $kJ\,mol^{-1}$.

$$400$$

Dispersion forces are temporary induced dipoles that exist in all molecules and atoms, and their magnitude typically increases with increasing __________.

molecular size (mass)

At $1\,atm$ and $25^\circ\text{C}$, fluorine ($F_2$) and chlorine ($Cl_2$) are gases, bromine ($Br_2$) is a liquid, and iodine ($I_2$) is a solid due to increasing __________ forces.

dispersion

Although carbon dioxide ($CO_2$) contains polar $C=O$ bonds, the molecule is nonpolar overall because its geometry is __________ and the bond dipoles cancel.

linear

Hydrogen bonding occurs exclusively when hydrogen is covalently bound to nitrogen, oxygen, or fluorine, and interacts with a lone pair on a(n) __________ atom.

N, O, or F

Solid ice is less dense than liquid water because water molecules orient to maximize hydrogen bonding, forming an open lattice with __________-sided empty channels.

six

When liquid water evaporates, the bond that is broken is the intermolecular __________ bond, which requires approximately $40+\,kJ\,mol^{-1}$.

hydrogen

1-hexanol has a higher boiling point than 1-propanol primarily because 1-hexanol possesses stronger __________ forces.

dispersion

On any boundary line of a temperature-pressure phase diagram, two phases are in __________.

dynamic equilibrium

The solid-liquid equilibrium line has a negative slope for water because solid ice is __________ dense than liquid water.

less

The temperature and pressure condition at which the solid, liquid, and gas phases of a substance simultaneously coexist in equilibrium is known as the __________.

triple point

At a given temperature, a liquid with stronger intermolecular forces will exhibit a __________ equilibrium vapor pressure.

lower