SC7 Types of Substances Flashcards
Describe the structure of a polymer
molecules made up of long chains of covalently bonded carbon atoms. They’re formed when lots of monomers join together
List 3 allotropes of carbon
Diamond, Graphite, Graphene, Fullerenes
Properties of Giant Covalent Structures
- low mp/bp
- don’t conduct electricity
- aren’t soluble
- strong covalent bonds
Describe Diamond
- made of a network of carbon atoms that each form four covalent bonds
- high mp
- rigid lattice structure
Describe Graphite
- each carbon atom only forms 3 covalent bonds, creating sheets of carbon atoms arranged in hexagons
- no bonds between layers
- high mp
Describe Graphene
- is one layer of graphite
- a sheet of carbon atoms joined together in hexagons
- sheet is just one atom thick
Describe Fullerenes
- molecules of carbon shaped like closed tubes or hollow balls
- they’re mainly made up of carbon atoms arranged in hexagons but can also contain pentagons
- fullerenes can be used to ‘cage’ other molecules
Define metallic bonding
Electrons in the outer shell of the metal atoms are delocalised; there are strong forces of electrostatic attraction between the positive metal ions and the shared negative electrons
Properties of metals
- high mp/bp
- shiny solids at room temperature
- aren’t soluble in water
- more dense as the ions are packed close together
- layers of atoms can slide over each other making metals malleable
- good conductors of electricity / heat as delocalised electrons can carry a current
Typical properties of non-metals
- dull looking
- brittle
- lower bp
- don’t generally conduct electricity
- lower density
Define Dot and Cross diagrams
Pros: - show how compounds are formed - where the electrons in the bonds or ions came from
Con: - don’t show size or how they’re arranged
Define 3D models
Pros: - shows arrangement of ions
Cons: - only shows outer layer of the substance
Define Ball and Stick Models
Pros : - visualise structures - more realistic
Cons: - don’t show correct scale or sizes
