C2 Flashcards
3 states of matter
Solid, liquid, gas
Forces of attraction, shape/volume and movement of solid
Strong - holds particles together, definite shape and volume, vibrate about their spot.
Forces of attraction, shape/volume and movement of liquid
Weak - randomly arranged and free to move past each other, define volume but do not have a definite shape, contantly move with random motion.
Forces of attraction, shape/volume and movement of gas
Very weak - free to move and far apart, no definite shape or volume, constantly move with random motion.
3 limitations of the simple particle model
Assumes all particles are spheres, assumes all particles are solids, does not show forces between the particles.
What elements react in ionic bonding?
A metal and a non-metal
What happens in an ionic bonding reaction?
A number of electrons passes from an atom to another atom so that they both achieve a full outer energy level.
2 properties of ionic compounds (giant ionic lattices)
Very high melting and boiling point - strong electrostatic forces require a lot of energy to break, cannot conduct electricity when solid - ions cannot move because of the forces.
What elements react in covalent bonding?
Non-metals
Define covalent bond
Shared pair of electrons.
2 properties of small covalent molecules (simple molecular substances)
Low MP and BP (gases and liquids at room temp.) - weak intermolecular forces between molecules, do not conduct electricity - molecules do not have an overall electric charge.
1 property of giant covalent molecules
High MP and BP (solid at room temp.) - have millions of strong covalent bonds
Why does diamond have a high MP and BP?
Each carbon atom forms 4 strong covalent bonds, which have to be broken when diamonds are melted.
Why cannot diamond conduct electricity?
There are no free electrons to carry electrical charge.
What atoms are silicon dioxide made from and what property does it have?
Oxygen and silicon atoms, high MP and BP.
3 properties of graphite
High MP and BP, soft and slippery, conducter of both electricity and heat
Why does graphite have a high MP and BP?
Each carbon atom forms 3 covalent bonds - forms hexagonal rings. It takes a great deal of energy to break these bonds.
Why is graphite soft and slippery?
Hexagonal rings are in layers - no covalent bonds between the layers so they can slide.
Why does graphite conduct electricity and heat?
Each carbon atom has a single electron that is not in a covalent bond - released from the atom (delocalised). These can conduct thermal energy and electricity.
Define graphene
Single layer of graphite - one atom thick.
2 properties of graphene
Excellent conducter of electricity - delocalised electrons like graphite, extremely strong.
Define fullerenes
Molecules of carbon atoms with hollow shapes, have hexagonal rings (can also have rings of 5 or 7 carbon atoms).
3 uses of fullerenes
Deliver a drug by caging other molecules, lubricants, catalysts.
2 properties of carbon nanotubes
High tensile strength (able to stretch without breaking), excellent conducters of heat and electricity
Use of carbon nanotubes
Reinforce materials without adding too much weight (e.g. tennis rackets).
Define polymers
Made up by joining together thousands of small, identical molecules (monomers).
1 property of polymers
Have a high MP and BP (solids at room temp.) - strong intermolecular forces of attraction.
What elements react in metallic bonding?
Metals
How are metals structured?
Consist of giant structure of atoms arranged in regular layers. Electrons in the outer energy level of each atom are delocalised. There is a strong electrostatic attraction (metallic bond) between the sea of delocalised negative electrons and the positive metal ions.
Why can metals conduct electricity?
Delocalised electrons can move and are charged so can carry an electric current and thermal energy.
Why do metals have a high MP and BP?
A great deal of energy is required to break the strong metallic bonds.
Why can metals be bent and shaped (malleable)?
The layers of atoms are able to slide over each other.
Define alloy
A mixture of metals
Why are alloys harder than pure metals?
The different sized of atoms distorts the layers, making it more difficult for them to slide over each other.
