Properties of Solids

4 types of solids

ionic, metallic, covalent network, covalent molecular

Properties of ionic solids

1. High melting and boiling points (ionic bonding=strongest IMF’s)

2. High brittleness b/c of repulsion of atoms with like charges when one later slides across another

3. Only conducts electricity when molten (heated to liquid state) or aqueous (b/c of mobile e-, which aren’t present in solid state)

Ionic solids: What is strength of ionic bond based on?

Coulombs Law

• Smaller size ions (smaller r, distance between charges)

• larger charge

=BIG lattice energy (strength of ionic bond)

Properties of Metallic Solids

1. good conductors of heat and electricity (sea of mobile valence e-)

2. malleable and ductile (NOT brittle). When stress applied, metal cores easily rearrange their structure

3. metal alloys- substitutional and interstitial

Substitutional metal alloy

• formed between elements of similar atomic radius

• atoms of one element substitue for atoms of another

Interstitial metal alloy

• formed between two elements with significantly different atomic radius

• smaller atoms fill in interstitial spaces between larger atoms

Properties of covalent network solids

1. atoms are covalently bonded in a 3-D network.

2. lots of strong covalent bonds= stronger melting point (takes lots of energy to break all the covalent bonds)

3. ex. dimond, quartz, SiC, SiO2

Properties of covalent molecular solid

1. has distinct/individual molecules, covalent bonds within molecules

2. low melting point= relatively weak IMF’s between molecules(LDG, dipole-dipole, H-bonding)

3. Nonconductors of electricity b/c valence e- are pulled tightly within covalent bonds