Giant Covalent Structures
- Similar to giant ionic structures except that there are no charged ions
- All the atoms are bonded to each other by strong covalent bonds
- They have very high melting and boiling points
- They don't conduct electricity - not even when molten
- They're usually soluble in water
- The main examples are : diamond and graphite, which are both made only from carbon atoms.
Diamond - Each carbon atom forms four covalent bonds in a very rigid giant covalent structure. This structure makes diamond the hardest natural substance, so it's used for drill tips.
Graphite - each carbon atom forms three covalent bonds, creating layers which are free to slide over each other. the layers are held together so loosely that they can be rubbed off onto paper. It also is the only non metal which is a good conductor of electricity.
Metal properties are all due to a sea of free electrons.
- Metals also consist of a giant structure
- Metallic bonds involve the all important ' free electrons', which produce all the properties of metals.
- These electrons came from the outer shell of every atom in the structure
- These electrons are free to move and so metals are good conductors of heat and electricity
- These atoms also hold the atoms together in a regular structure
- They also allow the atoms to slide over each other, causing metals to be malleable.