Covalent Bonding Flashcards
How are covalent bonds formed?
by atoms sharing electrons
Which type of atoms form covalent bonds between them?
non-metals and non-metals
Describe the structure and bonding of a giant covalent substance
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 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 than small molecules?
the intermolecular forces are stronger in large molecules
Why do most covalent substances not conduct electricity?
don’t have 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 structure
Explain why graphite is soft
the layers are not bonded so can slide over one another
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 a tube
