Properties and bonding in compounds
Summary of bonding
| Ionic lattice | Covalent network | Discrete covalent molecules | |
| Boiling and melting points | High | Very high | Low |
| State at room temperature | Solid | Solid | Liquid or gas |
| Conduction of electricity | Only when molten or in solution | Never (except graphite) | Never |
| Boiling and melting points | |
| Ionic lattice | High |
| Covalent network | Very high |
| Discrete covalent molecules | Low |
| State at room temperature | |
| Ionic lattice | Solid |
| Covalent network | Solid |
| Discrete covalent molecules | Liquid or gas |
| Conduction of electricity | |
| Ionic lattice | Only when molten or in solution |
| Covalent network | Never (except graphite) |
| Discrete covalent molecules | Never |
Ionic lattice
All ionic compounds have a high melting point and boiling point because many strong ionic bonds need to be broken. They conduct when molten or in solution as the ions are free to move. They can be broken down by electrolysis. They are generally soluble in water.
Covalent network
All covalent network structures have very high melting points and boiling points because many strong covalent bonds need to be broken. They are all hard, and do not conduct electricity because there are no free charges that can move. They do not dissolve.
Covalent molecular
They have low melting points and boiling points because the attractions between molecules are easy to overcome. They do not conduct electricity because there are no free charges to move. Some covalent molecular compounds have higher melting points than expected. Most do not dissolve in water but may dissolve in other solvents.