Properties of Materials Flashcards
Physical properties of a typical solid
The particles are very close together. This gives it a high density and makes it incompressible.
The particles vibrate about a fixed point and can’t move about freely
Physical properties of a typical liquid
Has a similar density to a solid and is virtually incompressible.
The particles move about freely and randomly within the liquid, allowing it to flow
Physical properties of a typical gas
The particles have loads more energy and are much further apart.
So the density is generally pretty low and it’s very compressible.
The particles move about freely, with not a lot of attraction between them, so they’ll quickly diffuse to fill a container
Explain how you change from a solid to a liquid or a liquid to a gas
You need to break the forces that are holding the particles together.
To do this you need to give the particles more energy (eg by heating them)
Explain what you have to do to melt or boil a simple covalent compound
Why do simple covalent compounds have relatively low melting and boiling points
You only have to overcome the intermolecular forces that hold the molecules together.
You don’t need to break the much stronger covalent bonds that hold the atoms together in the molecules
Explain how you’d turn diamond atoms into a liquid or a gas
You have to break the covalent bonds between the atoms
What determines the melting and boiling points of a substance?
The strength of the attraction between its particles
When will a substance only conduct electricity?
If it contains charged particles that are free to move
What does the solubility of a substance depend on?
Describe water as an example
The type of particles that it contains.
Water is a polar solvent, so substances that are polar or charged will dissolve in it well, whereas non-polar or uncharged substances won’t
Properties of Ionic Substance
High melting and boiling points
Solid at room temperature and pressure
Doesn’t conduct electricity when solid (ions are held in place)
Conducts electricity when liquid (ions are free to move)
Soluble in water
Properties of Simple Molecular Substance
Low melting and boiling points (involves breaking intermolecular forces but not covalent bonds).
May be solid at room temperature and pressure (eg I2) but usually liquid or gas.
Doesn’t conduct electricity when solid or liquid.
Soluble in water: depends on how polarised the molecule is
Properties of Macromolecular Substance
High melting and boiling points
Solid at room temperature and pressure
Doesn’t conduct electricity when solid (except graphite)
Doesn’t conduct electricity when liquid (sublimes rather than melting)
Insoluble in water
Properties of Metallic Substance
High melting and boiling points
Solid at room temperature and pressure
Conducts electricity when solid (due to delocalised electrons)
Conducts electricity when liquid (due to delocalised electrons)
Insoluble in water
