metals 3.5 Flashcards
component of a metal
lattice of positive metal ions
sea of delocalised electrons
what is metallic bonding
the electrostatic attraction between the positive metal ions and the negative delocalised electrons
strength of metallic bonding
very strong attraction
properties of metals
high mtp
conduct electricity
malleable
what is thermal decomposition
when heat energy is used to break down a substance
what do metal carbonates thermally decompose to form
metal oxides and carbon dioxide
thermal decomposition of copper carbonate colour change
green –> black
metal reactivity series lowest - highest
gold
silver
copper
hydrogen
lead
iron
zinc
carbon
aluminium
magnesium
calcium
lithium
sodium
potassium
metal and water –>
metal hydroxide + hydrogen
observations in metal + water reaction
effervescence
solid disappears
observations of group 1 metals + water
solid floats
effervescence
solid moves
solid disappears
why does universal indicator turn the water blue after a metal + water reaction
the metal hydroxides are alkalis because they donate OH-
metal + steam –>
metal oxide + hydrogen
acid + metal –>
salt + hydrogen
why is salt formed in an acid + metal reaction
hydrogen is displaced from an acid
observations in acid + metal reaction
metal disappears
fizzing
chemical test for hydrogen
lint splint produces a squeaky pop
what is a displacement reaction
more reactive metals can displace less reactive metals from their compounds
observations for a displacement reaction
solid colour change
solution colour change
where are most metals found
in the earth’s crust as compounds with oxygen and sulphur
what are the native metals
gold and silver
what are native metals
too unreactive to have combined with oxygen and sulphur
methods of extraction from ores
electrolysis
carbon extraction
what is carbon extraction
metals less reactive than carbon can be displaced by carbon
what is a redox reaction
using carbon to displace a metal from its oxide
reduction
loss of oxygen
reducing agent
takes oxygen away from something else
oxidation
gain of oxygen
oxidising agent
gives oxygen to something else
what is rusting
iron is oxidised to form rust
chemical name for rust
hydrated iron (III) oxide
what substances does rusting require
oxygen and water
how can rusting be prevented
barrier methods
sacrificial protection
galvanising
what are barrier methods
coating iron in paint, oil, grease or plastic prevents the iron coming into contact with water or oxygen
what is sacrificial protection
attach a block of a more reactive metal to the iron, displacing the iron from rust as soon as it forms
what is galvanising
coating the iron in zinc, coating + sacrificial protection
what are alloys
mixture of a metal with one or more other elements, usually metals or carbon
why are alloys different to pure metals
they are harder than pure metals because the different sized atoms prevent the layers of metal ions form sling over each other, less malleable
what is steel composed of
iron with small quantities of carbon
