Polymers and Giant Covalent Structures

What are polymers?

Long chains of repeating units, small units are linked together to form a long molecule that has repeating sections

What is a polymer joined by?

Strong covalent bonds

What is a repeating unit?

A part of a polymer that would make a complete polymer molecule if many of them were joined end to end

How do you find the molecular formula of a polymer?

Write down the molecular formula of the repeating unit in brackets, and put an 'n' outside

Why are polymers solid at room temperature?

The intermolecular forces between polymer molecules are larger than between simple covalent molecules, so more energy is needed to break them.

Why do polymers have lower boiling points than ionic or giant molecular compounds?

The intermolecular forces are still weaker than ionic or covalent bonds

What are the atoms in a giant covalent structure bonded by?

All the atoms are bonded by strong covalent bonds

Why do covalent structures have a very high melting and boiling point?

Lots of energy is needed to break the covalent bonds between the atoms

Do covalent structures conduct electricity?

No because they don't contain charged particles not even when molten (except graphite)

What are the main covalent structures?

Diamond, graphite, silicon dioxide

Diamond

Each carbon atom forms four covalent bonds in a very rigid giant covalent structure

Graphite

Each carbon atom forms three covalent bonds to create layers of hexagons. Each carbon atom also has one delocalised electron.

Silicon dioxide

Sometimes called silica, this is what sand is made of. Each grain of sand is one giant structure of silicon and oxygen