THE TOP 5 (or 6) THINGS TO KNOW ….IN NO PARTICULAR ORDER…..
General equations – memorise these! Really – do it NOW!!
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metal + oxygen → metal oxide
(very reactive) metal + water → metal hydroxide + hydrogen (metals like Na, Li, Ca…. Mg with hot water)
(reactive) acid + metal → salt + hydrogen (Remember Cu doesn’t react with dilute acids)
acid + base* → salt + water
*a base is a metal oxide eg CuO or metal hydroxide eg NaOH
acid + carbonate → salt + water + carbon dioxide
Know those polyatomic ions – memorise their NAMES and remember that if you use them
more than once, put them in brackets
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NH4+
CO32-
ammonium
carbonate
eg ammonium chloride: NH4Cl but ammonium sulfate: (NH4)2SO4
eg calcium carbonate CaCO3.
If aluminium carbonate existed (which it doesn’t), it would be Al2(CO3)3
2 SO4
sulfate
eg copper sulfate CuSO4 but iron(III) sulfate Fe2(SO4)3
 OH
hydroxide
eg sodium hydroxide NaOH but iron(II) hydroxide Fe(OH)2
 NO3
nitrate
eg silver nitrate AgNO3 but magnesium nitrate Mg(NO3)2
 HCO3
bicarbonate* eg potassium bicarbonate KHCO3 but calcium bicarbonate Ca(HCO3)2
*also known as hydrogen carbonate
Remember – don’t mess with the “little numbers” down the bottom of ions like CO32- and NO3- – they “stick”
with the “blob” and they are NOT part of the ions charge. It’s the charge at the top that decides “how many”
of these you need in a formula, CO32- and NO3-. (“little numbers” = subscripts, “blobs” = polyatomic ions)
Aluminium is really a lot more reactive than it appears to be
In the reactivity series Al is “right up there”…. right after Mg. (Mg > Al > Zn …..) BUT it does
not appear as reactive as it is.
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Aluminium has already reacted with oxygen in the air.
It has formed a tough thin protective layer of aluminium oxide on the metal surface.
The oxide layer prevents the aluminium metal BENEATH from coming into contact with other (NAMED)
substances
Named substances? Yes! Name the substances that aluminium might be expected to come into contact
with e.g. Aluminium is suitable for window frames as the oxide layer prevents it from reacting further
with oxygen in the air, with water (rain), or even dilute acids (in polluted rain/acid rain).
Aluminium will react with dilute acids (HCl and H2SO4) but the reaction starts slowly because first the acid
must react with the oxide layer (acid + base → salt + water) & then it will react with the “exposed” metal
(acid + metal → salt + hydrogen) Eg Al2O3 + 6HCl → 2AlCl3 + 3H2O and then 2Al + 6HCl → 2AlCl3 + 3H2
Some atoms form ions
Some of the atoms in lose or gain electrons from their valence (outermost) shells to form ions.
 These atoms will EITHER lose OR gain electron(s) to achieve a full valence shell, which is a stable
arrangement. (No “happy atoms” please!!   ). No atoms “wanting” to lose, “needing” to gain –
they just “do it!!”
 Metal atoms lose electron(s) and form positively charged ions.
 Non metal atoms gain electron(s) and form negatively charged ions.
 E.g. calcium metal has the atomic number 20…… so has the electron arrangement 2,8,8,2 …. so it loses
TWO electrons to achieve a full valence shell…which is a stable arrangement; the ion has the
arrangement 2,8,8 and the charge 2+ : we write it as Ca2+
 E.g. the non-metal chlorine has the atomic number 17…… so has the electron arrangement 2,8,7 …. so it
gains ONE electron to achieve a full valence shell…which is a stable arrangement; the ion has the
arrangement 2,8,8 and the charge 1- : we write Cl- (or Cl1-).
Chemical & Physical Properties of metals
Both are important when considering the “best metal for the job” but make sure you know the difference & that you
chose the appropriate property for the job.
 Physical properties are “what the metal is like” e.g. hard, strong, magnetic (or not), shiny, its colour, malleable,
ductile, good conductor of heat, good conductor of electric, high melting points, high boiling points, its density etc.
 Chemical properties are “how it behaves towards other elements/compounds” e.g. it reactions with oxygen, water
& dilute acids. At level 1 this is really confined to:
o
metal + oxygen → metal oxide
o
metal + water → metal hydroxide + hydrogen
o
acid + metal → salt + hydrogen
 Aluminium: is suitable for the bodies of planes because it is low density (physical property) & does not react with the
oxygen(in the air it flies through) or the water (in the clouds or rain) because of thin tough oxide layer (chemical
property).
 Copper: is suitable for the bottoms of cooking pans because it is a good conductor of heat (physical property), has a
high melting point (physical property) and it is malleable so it can be easily shaped into “pan” shapes (physical
property). It does not react with water and any cleaning detergents because it is unreactive (chemical property).
 Copper: is suitable for the electrical wires/cables because it is a good conductor of electricity (physical property), has
a high melting point (physical property) and it is ductile so it can be easily drawn into wires (physical property).
 Copper: is suitable for the water pipes in the home because it is unreactive (chemical property) and won’t react with
the water and any chemicals in it that flows through it, or with the air. It is malleable so it can be easily made into
pipe shapes (physical property). Note: Little reality check…. Certainly copper has a high meting point but just how
hot does the water in your plumbing system get!?! Does it matter that it has an attractive pinky orange colour for
water pipes? No
It’s all about using common sense - something that can escape us in a stressful exam
situation
o The sun is never going to get hot enough to melt a
o The low density of aluminium means that transport
metal roof or aluminium power lines – high melting
point is NOT relevant here.
o A metal roof is not really a disadvantage in
thunderstorms – how often are you in your attic
with your hand directly on the steel roof when a
thunderbolt strikes?
o We don’t cook peas in a saucepan by electrocution!
– good electrical conductivity is NOT relevant here.
Really!!
o Even if you could make a bath out of sodium metal
(fizz, fizz, fizzle….boom etc) the metal would be too
soft to hold its shape! (Sodium is soft enough to
squash between fingers (not advised) or cut with a
knife!
costs of large numbers of cans of drink will be
reduced (compared to thicker walled Al cans or
cans made from a denser metal) – it’s not so your
poor little arm doesn’t get tired drinking your can
of coke or carrying your shopping bag!
o Melting point, electrical conductivity and ductility
are ALL important if considering the thin wires
inside your toaster that toast your bread.
Hmm, I hope you get the general idea!
And a final word or two…..Don’t use “malleable and ductile” in the same breath, so to speak. Making a gold ring
relies on the malleability of gold, making an aluminium cable relies on the ductility of aluminium, producing aluminium
foil relies on its malleability (they roll it thinner and thinner). And you don’t MELT the metal for it to be malleable or
ductile – metals have this property as SOLIDS.
….And the cost of a metal ($$$) is never a chemical or physical property.
….It’s availability (rare or common) is never a chemical or physical property although this may influence its choice (iron
used in a lot of construction work) or value (eg silver and gold).
AND – the big one – the only metal that rusts is IRON (or the alloy steel that contains iron).
Never, ever say “copper doesn’t rust but iron does” – say “copper hardly corrodes at all due to its lack of chemical
reactivity BUT iron corrodes when it comes into contact with water and oxygen: The corrosion of iron is called
rusting!!”