States of matter

Properties of an ideal gas

1) The volume of gas molecules is negligible

2) Intermolecular FOA is negligible

3) Moves rapidly and randomly

4) Collisions between molecules are elastic

5) When in a container, they exert pressure

Properties of a real gas (pV = nRT)

At low pressures:

1) Volume is negligible (widely spaced)

2) Intermolecular FOA negligible (also at high temp)

At high pressures:

1) Gas molecules are closely packed together, so volume cannot be negligible

2) Intermolecular FOA becomes significant

Equation of fixed mass of an ideal gas (+ at constant temperature and pressure)

1) pV/T = constant

2) pV = constant

3) V/T = constant

Equations of relative molecular mass in gases

1) pV = nRT / Mr

2) Mr = mRT / pV

Structure of ionic solids

Lattice particles: positive and negative ions

Lattice forces: ionic bonds

Consists of positive and negative ions arranged alternatively in a crystal lattice held together by strong ionic bonds

E.g: NaCl, Mg2O

Properties of ionic solids

1) Hard, strong FOA

2) Brittle, possible to displace one layer of ions relative to the next

3) High MP

4) Good conductor of electricity when molten, mobile ions

Structure of metallic solids

Lattice particles: metal cations

Lattice forces: metallic bonds

A lattice of metal ions in a sea of delocalised electrons

Properties of metallic solids

1) High MP and BP

2) Good conductors of electricity

3) Strong but malleable and ductile, atoms can slide over each other without breaking bonds

Structure of simple molecular solids

Lattice particles: molecules

Lattice forces: intermolecular forces

A lattice of molecules held together by weak intermolecular forces

Eg. Iodine

Properties of simple molecular solids

1) Low MP and BP

2) Non-conductor of electricity when solid, liquid or aqueous

3) Soft, intermolecular forces are weak

4) Solid iodine is soluble in non-polar solvents (hexane)

Structure of ice

Lattice particles: Water molecules

Lattice forces: Hydrogen bonds

Simple molecular structure consisting of a lattice of water molecules held together by hydrogen bonds

Structure of giant molecular solids (mainly allotropes of carbon)

Lattice particles: Atoms

Lattice forces: Covalent bonds

A macromolecular structure consisting of a lattice of atoms held together by strong covalent bonds

Structure of diamond

Lattice particles: carbon atoms

Lattice forces: strong covalent bond’s

A macromolecular structure consisting of each C atom bonded to 4 other C atom in a continuous tetrahedral arrangement.

Properties of diamond

1) Very high MP and BP

2) Non-conductor of heat and electricity

3) Insoluble

4) Very hard

Structure of graphite

Lattice particles: carbon atoms

Lattice forces: covalent bonds within layer, weak id-id forces between layers

Within each layer, a carbon atom is covalently bonded to three other carbon atoms

Properties of graphite

1) High MP

2) Good conductor of electricity due to delocalised electrons between layers

3) Insoluble

4) Slippery and has lubricating properties, layers slide over each other

Structure of silicon oxide

Lattice particles: silicon atoms and oxygen atoms

Lattice forces: strong covalent bonds

Each Si covalently bonds to four O atoms

Each O atom bonded to two Si

Structure and properties of buckminsterfullerene

• Allotrope of carbon (60)

• Relatively soft, does not require much energy to overcome intermolecular forces

• Poor conductor of electricity but is able to also along with heat

• Only soluble in carbon disulfide and methylbenzene