Behaviour of metals
● Physical properties of metals
○ Shiny
○ Good conductors of heat and electricity
○ High density
○ Malleable and ductile
○ Usually solid at room temperature
○ Sonorous (makes bell-like sounds when struck)
Chemical properties of metals
● The chemistry of metals is studied by analysis their reactions with water, dilute acid and oxygen
● Based on those reactions, a reactivity series of metals can be produced
● Reactivity with water
○ Some metals react with water, either warm or cold or with steam
○ Metals that react with cold water form a metal hydroxide and hydrogen gas
○ For example, Ca + 2H2O → Ca(OH)2 + H2
○ Metals reacting with steam form metal oxide and hydrogen gas
○ For example, Zn + H2O → ZnO + H2
● Reactivity with acids
○ Most metals react with dilute acids such as HCl
○ When acids and metals react, the hydrogen atom in the acid is replace by the metal atom to
produce a salt and hydrogen gas
○ For example, Fe + 2HCl → FeCl2 + H2
● Reactivity with oxygen
○ Unreactive metals such as gold and copper do not react with acids
○ Some reactive metals such as alkali metals react with oxygen
○ Copper and iron can also react with oxygen although much more slowly
○ When metals react with oxygen, a metal oxide is formed for example copper
○ For example, 2Cu + O2 → 2CuO
● Alloys
○ An alloy is a mixture of 2 or more metals or a metal and a nonmetal
○ Alloys often have properties that can be very difficult to the metals they contain, for example
they can have more strength, hardness or resistance to corrosion or extreme temperatures
○ Alloys contain atoms of different sizes, which distorts the normally regular arrangements of
atoms in metals
○ This makes it more difficult for the laters to slide over each other, so alloys are usually much
harder than the pure metal
● Common alloys
○ Brass is an alloy of copper and zinc and is much stronger than either metal
○ Alloys of iron with tungsten are extremely hard and resistant to high temperatures
○ Alloys of iron mixed with chromium or nickel are resistant to corrosion
○ Aluminium is mixed with copper, manganese and silicon for aircraft body production as the alloy
is stronger but still has a low density
● Reactivity series
○ The chemistry of the metals is studied by analyzing their reaction with water dilute acid and
oxygen
○ Based on these reaction a reactivity series of metals can be produced
○ The series can be used to place a group if metals in order of reactivity based on the observation
of their reactions with water, acid and oxygen
● Reactivity series
○ Potassium , sodium , lithium, calcium, magnesium, aluminium, carbon, zinc, iron, tin, lead,
hydrogen, copper, silver gold and platinum
● Reactions with aqueous ions and oxides
○ The reactivity of metals increases going up the reactivity series
○ This means that a more reactive metal can displace a less reactive metal from its oxide by
heating
○ As magnesium is above copper in the reactivity series, magnesium is more reactive so can
displace copper
○ CuO + Mg → Cu + MgO
● Displacement reactions between metals and aqueous solutions of metal salts
○ Any metal will displace another metal that is below it in the reactivity series
○ This is because more reactive metals lose electrons and form ions more readily than less
reactive metals making them better reducing agents.
○ The less reactive metal is a better electron acceptor than the more reactive metal thus the less
reactive metal is reduced
○ Zn + CuSO4 (aq) → ZnSO4 (aq) + Cu
● Thermal decomposition reactions
○ Compounds decompose or breakdown when they are heated to sufficiently high temperatures
○ CaCO3 → CaO + CO2
● Thermal decomposition of metal hydroxides
○ Most metal hydroxides undergo thermal decomposition
○ Water and the corresponding metal oxide are products formed
○ Zn(OH)2 → ZnO + H2O
● Thermal decomposition of metal carbonates
○ The metal oxide and carbon dioxide are the products formed
○ MgCO3 → MgO + CO2
○ Group 1 carbonates do not decompose when heated due to high thermal stability
● Thermal decomposition of metal nitrates
○ Group 1 nitrates decompose forming the metal nitrite and oxygen
○ 2NaNO3 → 2NaNO2 + O2
○ Other metal nitrates decompose to form metal oxide, nitrogen dioxide and oxygen
○ 2Cu(NO3)2 → 2CuO + 4NO2 + O2
● Aluminium although placed high in reactivity series does not react with oxygen because the surface of
aluminium reacts with oxygen in air to form a protective coating of aluminium oxide
● It is tough, unreactive and corrosion resistant therefore prevents aluminium from reacting with water
