Crystalline Solids and Unit Cells

Flashcards covering key vocabulary related to intermolecular forces, gas laws, and the properties and types of cubic unit cells (Simple Cubic, Body-Centered Cubic, Face-Centered Cubic).

Intermolecular Forces

Attractions between molecules, including dipole-dipole and hydrogen bonding.

Permanent Dipole

Occurs when the Delta EN (electronegativity difference) between atoms in a bond is non-zero, indicating a polar bond.

Freezing Point Depression Equation

An equation in chemistry used to calculate the change in freezing point, typically denoted with a subscript 'f' (e.g., Delta Tf).

Vapor Pressure Lowering

The phenomenon where adding a solute to a solvent reduces the solvent's tendency to vaporize.

Crystalline Solids

Solids with a highly ordered arrangement of particles, characterized by repeating unit cells.

Amorphous

Describes a random arrangement of particles in a solid, contrasting with the ordered nature of crystalline structures.

Unit Cell

The smallest repeating portion that defines the overall structure of a crystalline solid.

Crystal Lattice

A repeating arrangement of unit cells that forms the complete structure of a crystalline solid.

Z

A term representing the number of atoms effectively contained within a given unit cell.

R

The radius of an atom or ion within a unit cell.

A

The edge length of a unit cell.

Simple Cubic Cell (SCC)

A type of cubic unit cell where particles are located only at the corners of the cube.

a = 2r (SCC)

The relationship between the edge length (a) and the atomic radius (r) in a simple cubic cell, where particles touch along the edges.

Atom Contribution (SCC Corner)

Each atom located at a corner of a simple cubic unit cell contributes 1/8 of its volume to the inside of that cube.

Z Value (SCC)

The total number of atoms effectively inside a simple cubic unit cell, which is 1 (8 corners * 1/8 contribution each).

Coordination Number

The number of nearest neighbors surrounding each particle in a crystal structure.

Coordination Number (SCC)

The coordination number for a simple cubic unit cell, which is 6.

Body-Centered Cubic (BCC)

A type of cubic unit cell with particles at each corner and one additional particle located at the dead center of the cube.

Body Diagonal (BCC)

The diagonal that runs through the body of a BCC cube, along which the particles touch.

c = 4r (BCC)

The relationship for the body diagonal (c) and the atomic radius (r) in a body-centered cubic cell, where c represents 4r.

a = 4r / sqrt(3) (BCC)

The relationship between the edge length (a) and the atomic radius (r) in a body-centered cubic unit cell.

Z Value (BCC)

The total number of atoms effectively inside a body-centered cubic unit cell, which is 2 (8 corners * 1/8 + 1 center atom).

Coordination Number (BCC)

The coordination number for a body-centered cubic unit cell, which is 8.

Face-Centered Cubic (FCC)

A type of cubic unit cell with particles at each corner and an additional particle located at the center of each face of the cube.

Face Diagonal (FCC)

The diagonal that runs across a face of an FCC cube, along which the particles touch.

b = 4r (FCC)

The relationship for a face diagonal (b) and the atomic radius (r) in a face-centered cubic cell, where b represents 4r.

Atom Contribution (FCC Face)

Each atom located at the center of a face of a unit cell contributes 1/2 of its volume to the inside of that cube.

Z Value (FCC)

The total number of atoms effectively inside a face-centered cubic unit cell, which is 4 (8 corners * 1/8 + 6 faces * 1/2).

Angstrom

A unit of length used for atomic measurements, equal to 10^-10 meters.

Volume of a Cube

Calculated as a^3, where 'a' is the edge length of the cube.