c3-structure and 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 giant molecules
Billions of atoms bonded together by strong covalent bonds
Describe the structure and bonding of small molecules
Small numbers of atoms group 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 joined together by strong covalent bonds in a long chain with with weak intermolecular forces between the chains
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 and small molecules?
The intermolecular forces are stronger in the molecules
Why do most covalent substances not conduct electricity?
They do not have the delocalised elections or irons?
Describe the structure and bonding in graphite
Each carbon atom is bonded to 3 others 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 so can slide over each other
What is graphene
One layer of graphite
Give two properties of graphene
Strong and conducts electricity
What is a fullerene
Hollow cage of carbon atoms arranged as a sphere or tube
