C2 - Bonding,structure and Properties of Matter Flashcards
what is a giant covalent structure
1) in a giant covalent structure all the atoms are bonded to each other by strong covalent bonds
2) they have very high melting and boiling points and lots of energy is needed to break the covalent bonds between the atoms
3) they do’t contain charged particles so they don’t conduct electricity - not even when molten
4) the main examples are diamond and graphite which are both made from carbon atoms
what is the structure of diamond
1) diamond has a giant covalent structure made up of carbon atoms that form four covalent bonds. this makes diamond very hard
2) these strong covalent bonds take a lot of energy to break and give diamond a very high melting point
3) it doesn’t conduct electricity because it has no free electrons or ions
what is the structure of graphite
1) in graphite each carbon atom only forms three covalent bonds creating sheets of carbon atoms arranged in hexagons
2) there aren’t any covalent bonds between the layers - they’re only held together weakly so they’re free to move over each other. this makes graphite soft and slippery so its ideal lubricating material
3) graphite has a high melting point - the covalent bonds in the layers need lots of energy to break
4) only three out of four of carbon’s outer shell electrons are used in bonds,so each carbon atom has one electron that’s delocalised and can move so graphite conducts electricity and thermal energy
what is the structure of graphene
1) graphene is a sheet of carbon atoms joined together in hexagons
2) this sheet is just one atom thick making it a 2D substance
3) the network of covalent bonds makes it very strong. it’s also incredibly light so it can be added to composite materials to improve their strength without adding much weight
4) like graphite it contains delocalised electrons so it can conduct electricity through the whole structure. this means it has the potential to be used in electronics
what is the structure of a fullerene
1) fullerenes are molecules of carbon shaped like closed tubes or hollow balls
2) they’re usually made up of carbon atoms arranged in hexagons but can also contain pentagons
3) fullerenes can be used to cage other molecules to the fullerene structure around another atom or molecule which is also then trapped inside. this could be used to deliver a drug in the body
4) fullerenes have a large surface area so they could help make great industrial cataylists. individual cayalist molecules could be attached to the fullerenes - fullerenes also make great lubricants
what type of structure do ionic compounds form
A regular lattice structure
what are the properties of an ionic compound
- high melting and boiling points due to strong bonds
- solid so they can’t conduct electricity
- they dissolve easily in water
what state are polymers in at room temperature and why
most are a solid because the forces between the molecules are larger than between simple covalent molecules so more energy is needed to break them
what is a polymer
a long chin of repeating units
what are the properties of metals
- most metals are a solid at room temperature
- the forces between the atoms are very strong so they need lots of energy to be broken
- metals are good conductors of electricity and heat
- most metals are malleable because the layers of atoms in the metal can slide over each other
what is an alloy
a mixture of 2 or more metals or a metal and another element. alloys are harder than pure metals so they are more suitable for everyday use.
what are the three things that the forces holding particles together depends on
- material
- pressure
- temperature
describe the particles in a solid
- in solids there are strong forces of attraction between particles which holds them close together in fixed positions to form a very regular lattice arrangement
- the particles don’t move from their positions so all solids keep a defined shape and volume and don’t flow like liquids
- the particles vibrate around their positions - the hotter the solid becomes the more they vibrate causing solids to expand slightly when heated
describe the particles in a liquid
- in liquids there is a weak force of attraction between the particles. they are randomly arranged and free to move past each other but they tend to stick closely together
- liquids have a definite volume but they don’t keep a definite shape and they will flow to fill the bottom of a container
- the particles are constantly moving with random motion. the hotter the liquid gets the faster they move causing them to expand slightly when heated
describe the particles in a gas
- in gasses the forces of attraction are very weak, they re free to move far apart, the particles in a gas travel in straight lines
- gasses don’t keep a definite shape or volume and will always fill the shape of the container
- the particles move constantly with random motion, the hotter the gas gets the faster they move, gasses either expand when heated or the pressure increases.
