Covalent Bonding Flashcards
How are covalent bonds formed?
By atoms sharing electrons.
Which type of atoms form covalent bonds between them?
Non-metals.
Describe the structure and bonding of a giant covalent structure.
Billions of atoms bonded together by strong covalent bonds.
Describe the structure and bonding of small molecules.
Small number of atoms grouped together into molecules with strong covalent bonds between the atoms, and weak intermolecular forces between the molecules.
Describe the structure and bonding of polymers.
Many identical molecules (monomers) joined together by strong covalent bonds in a long chain, with weak intermolecular forces between the molecules.
Why do giant covalent substances have high melting points?
It takes a lot of energy to break the strong covalent bonds between the atoms.
Why do small molecules have low melting points?
Only a small amount of energy is needed to break the weak intermolecular forces.
Why do large molecules have higher melting and boiling points than small molecules?
The intermolecular forces are stronger in the larger molecules.
Why do most covalent substances not conduct electricity?
They do not have any delocalised electrons or ions.
Describe the structure and bonding in graphite.
Each carbon atom is bonded to three others in hexagonal rings arranged in layers - it has delocalised electrons and weak forces between the layers.
Why can graphite conduct electricity?
The delocalised electrons can move through the graphite.
Explain why graphite is soft.
Layers are not bonded together so they can slide over each other.
What is graphene?
One layer of graphite.
Give two properties of graphine.
Strong, can conduct electricity.
What is a fullerene?
Hollow cage of carbon atoms arranged as a sphere or a tube.
