Chemistry 110: Chapter 13

Single-Crystalline

Particles are arranged in a pattern that repeats throughout the crystal. Single crystals have sharp edges with planar faces and take on regular geometric shapes such as cubes or prisms

Four types: Network, Molecular, Ionic, and metallic

Polycrystalline Solid

Short-range order; regions with repeating order, but lack long-range order

Amorphous solids

Lack of order; particles are closely packed, but in random arrangements with no repeating pattern.

Metallic solids

Composed of a single metallic element; held together by metallic bonds. metals valence electrons are not localized, and flow between cations in a ‘sea of electrons’, which allows particles to slide past one another

Ionic single crystalline solids

Composed of cations and anions held together by electrostatic forces. Strong attractions result in high melting points

-very brittle, and bad conductors (due to localized electrons)

Molecular Single Crystalline Solids

An array of discrete molecules of one type. Held together by intermolecular forces; tend to have lower melting points; do not have free-flowing electrons

-locked electrons result in lower conductivity

Network Solids

Atoms and molecules that form a continuous network through covalent bonds

-there are NO discrete molecules, and the electrons do not flow

Alloys

an Amorphous solid. Homogenous mixture of a metal and one other element, typically a metal. Is synthetic to have greater properties

ex: steel, brass

Polymers

Large molecules composed of a series of subunitt monomers; many monomers are linked with covalent bonds

ex: plastics

Polycrystalline Solids

Fall between the extremes of amorphous and crystalline solids; composed of microscopic crystals called grains

-grains are oriented randomly, no long range order