SL Chem - Unit #1: Structure and Properties of Solids

What are the physical properties of solids related to?

Related intermolecular forces

• Physical properties include: Hardness, melting/boiling point, conductivity, malleability, ductility

Lattice

Repeating pattern of atoms

Different categories of solids

1. Ionic Solids

2. Metallic Solids

3. Molecular Solids

4. Covalent Network Structures

Ionic Solids

A solid made up of very strong ionic bonds: A positively charged metal ions surrounded by a sea of mobile delocalized electron

• Form repeating lattice structure

Physical Properties:

• Hard, brittle, high melting/boiling points

Metallic Solids

Made up of metallic bonding, strong bond with a lack of directionality

• Continuous and compact structure

• The valence electrons are held together loosely - delocalized electrons that can conduct electricity (even in solid state)

Physical Properties:

• Shiny/silvery and flexible

Molecular Solids

Composed of covalently bonded (London/dipole-dipole forces) molecules

• Lattice structure packed in accordance of their shape/ size

Physical Properties:

• Low boiling/melting point, weak(soft) and can’t conduct electricity

Covalent Network Structures

Formed with a network of covalent bonds

• Interlocking of the covalent networks make it really strong (stronger than ionic)

Physical Properties:

• High boiling/melting points (more bonds to break with more energy), insoluble (attraction is too strong to be broken by the weak bonds of the solution), Doesn’t conduct electricity

Alloy

Mix of different metals to form one compound

• Stronger than pure metals - get the wanted properties of each metal

Why are alloys stronger

The difference of size make a bump which makes the plane of atoms/ion to slide over one another

Allotropes:

Different structural orientations of the same element

Diamond

Extremely hard since there is no plane of weakness in its structure

• High boiling/melting point, not soluble in water

Tetrahedral molecular geometry

Giant covalent structure

Graphite

Carbon atoms that are held together with weak london forces

• Has tons of space for delocalized ions so it’s makes a good conductor

giant covalent structure formed with layers of the same plane over and over

• High melting/boiling point

Graphene

Similar arrangement to graphite but it’s just a single layer (only one atom thick)

• Both the thinnest compound and the strongest

Excellent electrical conductivity

C₆₀Fullerene: Buckminsterfullerene

• 60 carbon atoms joined together to make a hexagonal/pentagonal spherical shape

NOT A COVALENT NETWORK COMPOUND