How to form a covalent bond?🤓
- Covalent bonding occurs when non-metal atoms react together. The non-metals share electrons to make covalent bonds.
- The positive nuclei of the bonded atoms are attracted, by electrostaticforces, to the shared pair of electrons, which makes the covalent bonds very strong.
- Each singlebond provides one extra shared electron for each atom.Each atom makes enough covalent bonds to gain a full outer shell, this makes the atom stable.
A common example of covalent bond in I/GCSE Chemistry
POLYMERS
Polymers are long chains of repeating units that are joined together by strong covalent bonds. The intermolecular forces between polymermolecules are larger than between simple covalent molecules as more energyis needed to break them. However, the intermolecular forces are still weaker then ionic or covalent bonds so they generally have lower boiling points than ionic or giant molecular compounds.
What is giant covalent structure?🤨
- In giant covalent structures, all the atoms are bonded together with strong covalentbonds.
- They have very high melting and boiling points as there is a lot of energy required to break the strong bonds between the atoms.
- They do not contain charged particles so they do not conduct electricity
- However,graphite is an exception
Examples of giant covalent structures in I/GCSE Chemistry are diamond, graphite and silicon dioxide.(These are all made from carbon atoms,though silicon dioxide also contains oxygen)
DIAMOND
- Each carbon atom has four covalent bonds
- Very hard
- The strong covalent bonds take a lot of energy to break-High melting point
- No free electrons - do not conduct electricity
GRAPHITE
- Each carbon atom has three covalent bonds
- It has sheets of carbon atoms arranged in hexagons
- There are no covalent bonds between the sheets so they can move over each other,making it slippery -good lubricant.
- Highmelting point
- Eachcarbon atom has one delocalised electron - it conducts electricity.
- One sheet of graphite is called graphene.
That's the end of covalent bond.
Drafted by Yoko Mak ( Chemistry)