Polymers and giant covalent structures

Question 1

What is a polymer ? - Examples of polymers include polyethylene, nylon, polyester, and cellulose

Answer 1

Lots of small units linked together to form a long molecules with repeating sections. All the atoms in a polymer are joined together by strong covalent bond

Question 2

How to find molecular formula of a polymer

Answer 2

Write down the molecular formula of repeating unit in bracket and put n on the outside

For example: polyethene (C2 H2) n

Question 3

why are most polymers solid at room temperature ?

Answer 3

Intermolecular forces between polymer molecules are larger compared to simple covalent molecules as lots of energy is needed to break the covalent bonds between the atoms so most polymers are solid at room temperature.

Intermolecular force are still weaker than ionic or covalent bonding so they generally have lower bp than ionic or giant molecular compounds ( Diamond, graphite and graphene )

Question 4

Giant covalent structures are macromolecules

• atom
• bp/mp
• electricity
• exeptions

Answer 4

1) All the atoms are bonded together by strong covalent bonds
2) High mp, bp as lots of energy is required to break the strong covalent bonds between the atoms
3) Don’t contain charged particles = don’t conduct electricity - not even when molten ( exception - graphite )
4) main example is diamond and graphite which are made of carbon atoms and silica

Question 5

What’s Diamond - see page 117 for diagram of all -
What’s graphite ?
What’s silicone dioxide?

Answer 5

Each carbon atom form 4 covalent bonds in a very rigid covalent structure

• Graphite - Each carbon atom form 3 covalent bonds to create layers of hexagons. Each carbon atom has one delocalised electron
• This is what sand is made of. one grain of sand is one giant structure of silicone and oxygen