ch 12 solids and modern materials

Polymers

Substances containing long chains of atoms (usually carbon) connected by covalent bonds.

Nanomaterials

Solids in which the dimensions of individual crystals are reduced to the order of 1-100 nm.

X ray diffraction

Technique used to determine the arrangement of atoms in a crystal.

Unit Cell

The smallest piece of the crystal required to show a repeating pattern.

Crystalline Solids

Solids with a defined geometric structure formed by the orderly arrangement of atoms.

Amorphous Solids

Solids that lack a clear geometric structure and have a random arrangement of atoms.

Cubic Unit Cells

Unit cells of metals where all sides are equal and all angles are 90 degrees.

Coordination Number

The number of atoms immediately surrounding a given atom in a crystal structure.

Alloy

A homogeneous mixture of two or more metals.

Substitutional Alloy

An alloy formed when solute atoms occupy positions normally occupied by solvent atoms.

Interstitial Alloy

An alloy formed when solute atoms occupy interstitial positions between solvent atoms.

Electron Sea Model

A model describing metals as an array of cations surrounded by a 'sea' of delocalized electrons.

Molecular Orbital Model

A model that describes the behavior of electrons in molecular systems and is used to study metallic bonding.

Valence Band

The band formed from bonding molecular orbitals in a semiconductor.

Conduction Band

The band formed from antibonding molecular orbitals in a semiconductor.

Energy Band Gap (Eg)

The energy difference between the valence band and conduction band in semiconductors.

Thermoplastics

Plastic materials that can be reshaped through heat and pressure.

Thermosetting Plastics

Plastics that undergo irreversible chemical processes and cannot be reshaped once set.

Quantum Dots

Semiconductor particles of approximately 1 to 10 nm in size that exhibit unique electronic properties.

Buckyballs (C60)

Molecules composed of 60 carbon atoms in a spherical structure.

Graphene

A single layer of carbon atoms arranged in a two-dimensional lattice.