C3 Flashcards
Why are solids hard to compress?
- The particles are packed together in a regular pattern with no space between them
- Have a fixed shape and cannot flow from place to place
Why can’t solids move from place to place?
The particles can vibrate but not move
Why are liquids hard to compress?
Particles are close together with no space between them
Why are gases easy to compress?
The particles in a gas are widely spread and fill the spaces of the container
How do gases move?
Quickly and randomly
How can you change the state of a substance?
Putting in or taking out energy
What do you have to do to convert a solid to a liquid?
Put energy in as the particles in a liquid move. The energy is used to break the forces of attraction
What does stronger the forces of attraction mean?
More energy needed to break them and higher the melting point
Why do substances have low boiling points?
Have low forces of attraction
How do you turn gas into a liquid?
Condense
What are the limitations of the simple particle model?
- All particles are solid spheres
- No forces between particles
Why do elements react?
To form a full outer energy level
What is ionic bonding?
When a metal reacts with a non metal
What do ionic compounds form?
Giant structures
What are giant ionic lattices?
When negative ios are surrounded by positive ions
What are electrostatic forces?
Giant ionic lattices have strong forces of attraction between positive and negative ions
What are ionic bonds?
Electrostatic forces that hold negative and positive ions together
Facts about ionic compounds?
- Have high melting and boiling points
- Cannot conduct electricity when solids
Why do ionic compounds have high melting and boiling points?
The electrostatic forces require a lot of heat energy to break
Why can’t ionic compounds conduct electricity?
Ions cannot move and locked in strong electrostatic forces of attraction
When can ionic compounds conduct electricity?
Melted or dissolved in water (the ions can move and carry the charge)
What are facts about ionic compounds?
- Form giant structures where every positive ion is surrounded by negative ions
- Giant ionic lattices have strong forces of attraction (electrostatic forces)
What is covalent bonding?
Sharing electrons
When does covalent bonding happen?
Between non metal elements
Properties of small covalent molecules?
Have low melting and boiling points (usually gases or liquids at room temp)
Why do small molecules have low melting and boiling point?
- atoms are held by strong covalent bonds
- Very weak forces between intermolecular forces
What does intermolecular mean?
Betwen forces
Why do small covalent bonds have low melting and boiling points?
Weak intermolecular forces and does not require a lot of energy to break
Why is it when alkanes get larger the boiling point increases?
The intermolecular forces increase and require more energy
Why do small covalent molecules not conduct electricity?
Molecules do not have an overall electric charge
Facts about giant covalent molecules?
Always solid at room temperature
Why do giant covalents always have high melting and boiling points?
Millions of strong covalent bonds
How is diamond formed?
From carbon
How is diamond formed?
Each carbon atom forms 4 strong covalent bonds
Why does diamond have a high melting point?
It has a lot of carbon covalent bonds so requires a lot of energy
Why can’t diamond conducts electricity?
No free electrons to carry out electrical charge
Why does silicone dioxide have a high melting and boiling point?
Huge number of strong covalent bonds must be broken and requires energy
Graphite properties?
- High melting and boiling point
- Soft and slippery
- Great conductor for electricity and heat
How is graphite formed?
Element carbon and forms 3 covalent bonds from hexagonal rings
Why does graphite have a high boiling and melting point?
Has strong covalent bonds
Why is graphite slippery?
No covalent bonds between layers so they can slide
What can delocalised electrons do?
Conduct heat and electricity
Why is graphite not a metal?
Based on element carbon
Why is graphite a good conductor to heat and electricity?
Have delocalised electrons which can move
What is graphene?
A single layer of graphite
One atom thick
Graphene properties?
- Good conductor of electricity
- Very strong
Why is graphene a good conductor of electricity?
It has delocalised electrons
What are fullerenes?
Molecules of carbon atoms with hollow shapes
How are fullerenes formed?
Hexagonal rings of carbon atoms
Whats c60?
Buckminsterfullerene
What are the uses of fullerenes?
- Pharmaceutical delivery
- Lubricants
- Catalysts
Carbon nanotubes properties?
- High strength and can be stretched
- Excellent conductors of heat and electricity
Uses of carbon nanotubes?
Reinforce materials eg tennis rackets
How are polymers made?
Joining thousands of small identical molecules
What are monomers?
Alkene molecules
Why are most polymers solids at room temperature?
The intermolecular forces between polymers are strong
What are the electrons on the outer energy level of a metal?
Delocalised
Whats between the sea delocalised electroms and positive metal ions?
Strong electrostatic attraction
Whats a metallic bond?
Electrostatic bond in metals
Why are metals great conductors of heat?
- Delocalised electrons can move
- Charged metals carry electricity
Why can metals be bent and shaped?
Able to slide over each other
Metal properties?
- Bent and shapes
- Good heat and electricty conductors
What is an alloy?
A mixture of metals
How are alloys harder than metals?
Different sizes of atoms distorts the layers making it harder to slide over
What is a micrometer?
1 x 10-6
What is a nanometer?
1 x 10-9
Coarse particle diameter?
1x10-5 and 2.5 x 10-6
What is the diameter of nano particles?
1 -100 nanometeres
Contain few hundred atoms
What happens when particle size decreases 10 times?
SA - VR increases 10 times
Uses of nanoparticles?
- Medicines
- Suncreams
- Cosmetics
- Deodrants
- Electronics
- Catalysts
Risks of nanoparticles?
- can be absorbed by our body and enter our cells
- No one knows long term effects
