Solid State Matter

Impurity atoms

(1)

Vacancy

(2)

Interstitial impurity

(3)

Crystalline Solid

• A solid whose atoms, ions, or molecules are arranged in a regular, repeating pattern

• Has a highly ordered internal structure

• Usually has a sharp, well-defined melting point

• Most metals and ionic compounds are crystalline

Amorphous Solid

• A solid whose particles are arranged randomly

• Has no long-range repeating pattern

• Softens gradually instead of melting at one exact temperature

• Particles are randomly arranged

• Also called non-crystalline solids

Crystal Lattice

• The repeating three-dimensional arrangement of particles in a crystalline solid

• Gives crystals their regular shape and many of their physical properties

Long-Range Order

• A repeating arrangement of particles that extends throughout the entire crystal

• Found only in crystalline solids

Glass and Wax

Two examples of non-crystalline solids

Fused Silica

• An amorphous form of silicon dioxide

• Produced by rapidly cooling molten silicon dioxide

• Has no repeating crystal structure

Ionic Solid

• A solid made of positive and negative ions'

• Held together by ionic (electrostatic) attractions

• Usually hard and brittle

• Has a high melting point

• Conducts electricity only when molten or dissolved

Aluminum oxide (alumina)

• Al₂O₃

• Ionic solid (with some covalent character)

• Is white, odorless crystalline solid

• Extremely hard (Mohn hardness is ≈ 9, just second only to diamond)

• Very high melting point (≈ 2050 °C)

• Excellent electrical insulator

• Good thermal conductor

• Highly resistant to corrosion and chemical attack

• Used to make high-strength ceramic tiles, spark plug insulators, laboratory crucibles, and wear-resistant machine parts

Metallic Solid

• A solid made entirely of metal atoms

• Held together by metallic bonding

• Good conductor of electricity and heat

• Usually shiny, malleable, and ductile

• Examples: Cu, Fe, and Ti etc.

Covalent Network Solid

• A solid made of atoms connected by a giant network of covalent bonds

• Extremely hard

• Has very high melting points

• Usually does not conduct electricity

Diamond (covalent crystal)

• A covalent network solid made entirely of carbon

• Every carbon atom bonds to four neighboring carbon atoms

• Extremely hard

• Very high melting point

• Poor electrical conductor

Silicon dioxide (covalent crystal)

Silicon carbide (covalent crystal)

Molecular Solid

• A solid made of neutral molecules

• Molecules are held together by intermolecular forces

• Usually has low melting points

• Poor conductor of electricity

• Examples: carbon dioxide, iodine, ice, and sucrose

Ionic Bond

• Electrostatic attraction between positive and negative ions

• Holds ionic solids together

• Produces strong, rigid crystal structures

Metallic Bond

• Attraction between positive metal ions and a sea of delocalized electrons

• Responsible for metals' conductivity and malleability

Sea of Delocalized Electrons

• Electrons that are free to move throughout a metal

• Allow metals to conduct electricity and heat

• Help hold metal atoms together

Covalent Bond

• A chemical bond formed by sharing electrons

• Responsible for the strong structures of covalent network solids.

Intermolecular Forces (IMFs)

• Attractive forces between separate molecules

• Much weaker than ionic or covalent bonds

• Hold molecular solids together

Yes, it is true

Is it true that crystalline solids melt at one specific temperature and amorphous solids soften over a range of temperatures

Brittleness

The tendency of a material to break or shatter instead of bending. Common property of ionic solids.

Malleability

The ability of a material to be hammered into thin sheets without breaking. Characteristic property of metals.

Ductility

The ability of a material to be stretched into wires. Characteristic property of metals

Metallic Luster

The shiny appearance of metals caused by reflection of light from mobile electrons.

Electrical Conductivity

• The ability of a material to allow electric current to flow

• Metals conduct well

• Ionic solids conduct only when molten or dissolved

• Most molecular and covalent network solids do not have this property

Thermal Conductivity

• The ability of a material to transfer heat

• Metals are excellent at this

Allotrope

• Different structural forms of the same element

• Each of them has different physical properties

Graphite

• A covalent network solid made of layers of carbon atoms

• Each carbon atom bonds to three neighboring carbon atoms

• Layers slide easily over one another

• Soft

• Good conductor of electricity

Graphene

• A single layer of graphite that is one atom thick

• Extremely strong and lightweight

• Excellent conductor of electricity and heat

• Used in advanced electronics, batteries, and composite materials

Buckminsterfullerene (Buckyball)

• A hollow spherical molecule made entirely of carbon atoms

• Built from graphene-like hexagons and pentagons

• Used in nanotechnology and materials science

Carbon Nanotube

• A cylindrical tube made by rolling a sheet of graphene

• Extremely strong

• Excellent electrical conductor

• Used in electronics and advanced materials

Crystal Defect

• An imperfection in the regular arrangement of particles in a crystal

• Can change a material's electrical and mechanical properties

Vacancy Defect

• A crystal defect where an atom or ion is missing from its normal position.

• Leaves an empty space in the crystal lattice

Interstitial Site

• A space between the normal positions of atoms in a crystal

• Sometimes occupied by an extra atom or ion.

Impurity

• A different atom or ion present within a crystal

• Can distort the crystal structure and change its properties

Doping

• The intentional addition of small amounts of impurities into a crystal.

• Used to modify electrical properties.

• Essential for manufacturing semiconductor devices and computer chips

Carbon Nanofoam

• A lightweight, porous allotrope (ability to also absorb fluid)
  of carbon known for its unique structure, ferromagnetic properties, and potential applications in energy storage and electronics.

• A sponge-like network of interconnected carbon atoms containing millions of tiny pores.

• Mainly used for water purification and hydrogen storage research