CAPP Chemistry Chapter 10

What is the difference between intramolecular and intermolecular forces?

Intramolecular forces are bonds within a molecule (covalent/ionic) that hold atoms together. Intermolecular forces are attractions between molecules that determine physical properties like boiling and melting points.

What are Dipole–Dipole forces?

Attractions between the positive end of one polar molecule and the negative end of another.

What is Hydrogen Bonding?

A strong type of dipole-dipole force occurring when Hydrogen is bonded to a highly electronegative atom (Nitrogen, Oxygen, or Fluorine).

What are London Dispersion Forces (LDF)?

Temporary, "accidental" dipoles present in all molecules (even nonpolar ones). They increase in strength as the size/polarizability of the molecule increases.

What is Surface Tension?

The resistance of a liquid to increasing its surface area. Stronger IMFs result in it to be higher.

What two forces drive Capillary Action?

1. Cohesive forces (attraction between like molecules) and 2. Adhesive forces (attraction between liquid molecules and the container walls).

What is Viscosity?

A liquid's resistance to flow. Liquids with strong IMFs or complex molecular shapes tend to be more viscous.

What is the difference between Crystalline and Amorphous solids?

Crystalline solids have a highly regular, repeating arrangement of components (lattice). Amorphous solids have considerable disorder (e.g., glass).

Describe the "Electron Sea Model" for Metallic Solids.

A lattice of metal cations submerged in a "sea" of mobile valence electrons, which accounts for high conductivity and malleability.

Give two examples of Network Atomic Solids.

Diamond and Graphite (both forms of Carbon). These are "giant molecules" held by strong covalent bonds.

What characterizes Ionic Solids?

They are composed of ions at the lattice points and held together by strong electrostatic (ionic) attractions (e.g., NaCl).

What is Vapor Pressure?

The pressure of the vapor present at equilibrium with its liquid. It increases with temperature and decreases with stronger IMFs.

On a phase diagram, what is the Triple Point?

The specific temperature and pressure where the solid, liquid, and gas phases all coexist in equilibrium.

On a phase diagram, what is the Critical Point?

The temperature and pressure beyond which the liquid and gas phases are indistinguishable (forming a supercritical fluid).

Why does ice float on water?

Because the density of solid water (ice) is lower than liquid water due to the open hexagonal structure formed by hydrogen bonding.

Cohesive Forces

Liquid molecules sticking to each other.

Adhesive Forces

Liquid molecules sticking to the container

Capillary Action

When a liquid climbs up a narrow tube spontaneously. It happens because of a tug-of-war between adhesive and cohesive forces.

Viscosity

How "thick" a liquid is.

High viscosity means

it pours slowly (like molasses).

Low viscosity means

it pours fast (like water).

Crystalline Solid

A solid with a perfectly organized, repeating pattern (like a diamond or salt).

Amorphous Solid

A solid with a messy, random internal structure (like glass or plastic).

Lattice

The 3D "grid" or framework that shows where atoms are positioned in a crystal.

Unit Cell

The smallest "building block" or repeating unit of a crystal lattice.

Molecular Solid

A solid made of individual molecules held by weak IMFs (like ice or dry ice). They melt easily.

Ionic Solid

A solid made of oppositely charged ions (like table salt). They are very stable and have high melting points.

Vapor Pressure

How much a liquid "wants" to turn into a gas. High vapor pressure means it evaporates quickly.

Boiling Point

The temperature where a liquid's vapor pressure equals the surrounding atmospheric pressure.

Phase Diagram

A "map" or graph that shows which state (solid, liquid, gas) a substance is in at different temperatures and pressures.

Triple Point

The exact temperature and pressure where a substance is a solid, liquid, and gas all at the same time.

Critical Point

The point where the temperature is so high that you can no longer tell the difference between a liquid and a gas.