Implications of differences in structure Ionic solids  Conduct electricity in solution (not as solid)  Ions break free from electrical attraction when in solution and are free to migrate and carry the current Electrical attraction strongly holding ions together even ions themselves do not touch Cation (attracted to cathode) Anion (attracted to anode)

Further implications for ionic compounds High melting point  Requires a great amount of energy to break the positive and negative charges apart Very hard & brittle  Strong electrical attraction accounts for hardness  Compounds themselves imply “don’t want to bend” so when we add a lot of energy (like a hammer), the compound tends to shatter in several places (brittle)

Molecular Compounds Do not conduct electricity either in solid or liquid phase  Primary building block consists of a neutral molecule Why no conduction? In each molecule, electrons are held tightly by the positive cores and are unable to move

Further implications for molecular compounds Low melting & boiling point  Though interactions between atoms in a molecule are strong….the interactions between individual molecules are relatively weak Example: The Halogens F 2 & Cl 2 both gases at RT (RT is above their BP) Br 2 is liquid at RT (RT is greater than its MP, but lower than its BP) I 2 is a solid at RT (RT is lower than its MP)