CH10: Intermolecular Forces, Liquids, Phase Transitions, and Solid Structures

Vocabulary practice flashcards covering intermolecular forces, properties of liquids, phase transitions, Clausius-Clapeyron calculations, phase diagrams, and crystalline solid structures.

Bonding Forces

Attractive forces that occur within an individual molecule that hold the individual atoms or ions together, such as covalent and ionic bonds.

Intermolecular Forces

Attractive forces that occur between different molecules, which determine physical states, viscosity, volatility, melting points, and boiling points.

Dispersion Forces

Short-lived attractive forces resulting from the constant motion of electrons within molecules, creating temporary dipoles in both polar and non-polar molecules.

Dipole-Dipole Forces

Intermolecular forces occurring in polar substances resulting from attractions between the positive and negative ends of permanent dipoles on different molecules.

Hydrogen Bonding

Strong intermolecular attractions formed between polar molecules containing hydrogen covalently bonded to fluorine, oxygen, or nitrogen ($F$, $O$, or $N$).

Cohesive Force

Intermolecular forces of attraction that occur between identical molecules within a liquid.

Surface Tension

The energy required to increase the surface area of a liquid, or the force required to increase the length of a liquid surface by a given amount.

Viscosity

The resistance of a liquid to flow, which increases with stronger intermolecular forces and longer, flexible molecular shapes.

Vapor Pressure

The pressure exerted by a vapor when the liquid and vapor phases of a substance are in dynamic equilibrium in a closed container.

Intensive Property

A physical or chemical property unique to a substance that can be used to identify it and does not depend on the amount of sample present.

Boiling Point

The temperature at which the vapor pressure of a liquid is equal to the external pressure above the liquid.

Normal Boiling Point

The temperature at which a liquid boils at mean sea-level atmospheric pressure of $1\,\text{atm}$ ($760\,\text{torr}$ ).

Heat of Vaporization

The amount of energy required to change one gram of a liquid at its boiling point into a vapor.

Clausius-Clapeyron Equation

An equation relating vapor pressure and temperature: $\ln(P_{vap}) = -\frac{\Delta H_{vap}}{R}\left(\frac{1}{T}\right) + \ln(A)$, where $R = 8.314\,\text{J}\cdot\text{mol}^{-1}\cdot\text{K}^{-1}$.

Critical Temperature

The highest temperature at which a distinct liquid phase can form, above which no amount of pressure will cause liquefaction.

Critical Pressure

The pressure required to liquefy a substance at its critical temperature.

Supercritical Fluid

A state of matter existing at temperatures and pressures above a substance's critical temperature and critical pressure, exhibiting properties of both gases and liquids.

Phase Diagram

A graph showing which physical state or states of a substance will be present under given conditions of temperature and pressure.

Triple Point

The specific combination of temperature and pressure at which all three phases (solid, liquid, gas) coexist in equilibrium.

Critical Point

The point on a phase diagram corresponding to the critical temperature and critical pressure of a substance.

Crystalline Solid

A solid in which the constituent atoms, molecules, or ions are arranged in an orderly, repeating three-dimensional pattern.

Amorphous Solid

A solid formed when freezing occurs before the constituent atoms, molecules, or ions can arrange themselves in an orderly pattern.

Ionic Solids

Crystalline solids composed of cations and anions held together by strong electrostatic ionic bonds, characterized by high melting points.

Molecular Solids

Crystalline solids composed of neutral molecules held together by intermolecular forces, characterized by relatively low melting points.

Metallic Solids

Crystalline solids composed of metal cations held together by electrostatic interaction with a sea of delocalized valence electrons.

Network Covalent Solids

Crystalline solids composed of atoms held together throughout the crystal by a continuous network of strong covalent bonds.

Unit Cell

The smallest repeating structural unit that makes up the overall lattice of a crystalline solid.

Coordination Number

The number of surrounding atoms or ions with which each central atom or ion is in direct contact within a crystal structure.

Packing Efficiency

The percentage of the total volume of a unit cell that is occupied by its constituent atoms or ions.

Simple Cubic Structure

A unit cell arrangement with one atom at each corner of a cube, possessing $1$ net atom per unit cell, a coordination number of $6$, and a packing efficiency of $52\%$.

Body-Centered Cubic Structure

A unit cell arrangement with one atom at each corner and one atom in the center of the cube, possessing $2$ net atoms per unit cell, a coordination number of $8$, and a packing efficiency of $68\%$.

Face-Centered Cubic Structure

A closest-packed unit cell arrangement with one atom at each corner and one atom in the center of each face, possessing $4$ net atoms per unit cell, a coordination number of $12$, and a packing efficiency of $74.04\%$.