paper two Flashcards
(38 cards)
what is metallic bonding?
the strong electrostatic attraction between positive metal ions and delocalised electrons
can metals conduct electricity?
yes
why can metals conduct electricity?
they contain delocalised electrons which are free to move
are metals malleable?
yes
why are metals malleable?
rows of metal ions can slide over each other easily
are metals strong?
yes
why are metals strong?
strong electrostatic attraction between positive metal ions and delocalised electrons
do metals have high or low melting points?
high
why do metals have high melting points?
the strong electrostatic attraction between positive metal ions and delocalised electrons requires lots of energy to overcome
what are alloys?
a mixture of a metal and one or more elements, usually other metals or carbon
why are alloys harder than pure metals?
in an alloy, the elements have slightly differently sized elements, which breaks up the normal lattice arrangement and prevents the layers sliding over each other
what are the uses of aluminium?
- it is used for cables, some cars (because it’s light), planes, pots, and pans
- it is useful because of it’s lack of corrosion, it’s low density, it’s strength when alloyed, and it is a good conductor of heat and electricity
- it doesn’t corrode because it forms aluminium oxide on the surface
what is mild steel made up of?
iron and up to 0.25% carbon
what are the uses of mild steel?
- nails, car bodies, ships, and bridges
- mild carbon is strong, hard, malleable, and ductile
- it rusts when exposed to oxygen and water
what is high-carbon steel made up of?
iron, 0.6-1.2% carbon, and small amounts of manganese
what are the uses of high-carbon steel
- it is used for cutting tools and masonry nails
- it is harder and more than resistant than mild steel, but also more brittle
what is stainless steel made up of?
iron, chromium, and usually nickel
what are the uses of stainless steel?
- it is used in kitchen sinks, sauce pans, knives and forks, and gardening tools
- it is also used in brewing, dairy, and chemical industries
- it is resistant to corrosion
what are the uses of copper?
- it is used in electrical wires, pots and pans, surfaces in hospitals, and water pipes
- it is a good conductor of heat and electricity, it is unreactive, malleable, and has antimicrobial properties
what method is used to prepare a pure, dry sample of a soluble salt starting from an acid and an alkali?
use the titration method:
- do the titration
- use the titration values to measure out the right amount of acid and solid with no indicator!! bc it prevents the formation of crystals
- transfer to evaporating basin + heat
- allow solution to cool
- pick out crystals
- wash with distilled water
- pat dry with filter paper
what method is used to prepare a pure, dry sample of an insoluble salt starting from two soluble reactants?
the precipitation method:
- mix the two solutions together in a beaker
- stir with a rod
- filter with a filter paper + funnel
- wash with distilled water
- leave to dry in a warm oven
what colour is the precipitate formed when making a sample of lead (ii) sulphate using the precipitation method?
white precipitate
why does the reactivity of the metals in group 1 increase as you go down the group?
- they all need to lose one electron
- number of electron shells increases going down the group
- outer electron gets further away from nucleus
- attraction between nucleus and electron decrease
- therefore it is easier to remove
why does the reactivity of the atoms in group 7 decrease as you go down the group?
- all need to gain one electron
- number of shells increases as you go down the group
- so incoming electron is further away
- so weaker attraction between incoming electron and nucleus
- so harder to gain the electron
