The Activity Series
• ranks metals according to the ease
they undergo oxidation
o higher up metals are more reactive
• displace those lower down from a
solution
o notice hydrogen in the series
• metals above H will react in weak acids
• metals below will not react with weak
acids
• the most reactive metal ends up as an
ion and then reacts to form a new
compound
o Zn + CuSO4 
• Zn is more reactive than Cu
• Zn is oxidized (goes from 0 to +2) and then
bonds with the -2 SO4
• Zn + CuSO4  Cu + ZnSO4
o Ni + 2AgNO3  2Ag + Ni(NO3)2
• Ni is more reactive than Ag
• Ni is oxidized (goes from 0 to +2) and then
bonds with the -1 NO3
o Ag + Zn(NO3)2  Ag + Zn (NO3)2
• Zn is more reactive than Ag
• no reaction
oZn will stay a 2+ ion and remain
bonded to the 1- nitrate
o Mg + H+  ?
• Mg is more reactive than H
obecomes an ion
oMg + 2 H+  H2 + Mg2+
o Na+ + Al  ?
• Na is more reactive that Al
• no reaction, Na+ will remain a ion
Nonmetals
• Which can occur?
• Cl2 + 2I-  I2 + 2 ClYes
• I2 + 2 Cl- 
No
• Consider the following reactions of three
unknown metals X, Y and Z.
2XNO3(aq) + Y(s) → 2X(s) + Y(NO3)2(aq)
Y(NO3)2(aq) + Z(s) → No reaction
2XNO3(aq) + Z(s) → 2X(s) + Z(NO3)2(aq)
What is the order of increasing reactivity of
the metals (least reactive first)?
X < Z < Y
Watch These Reactions!
Combination (Synthesis) Reactions
• a chemical change in which two or more
substances react to form a single new
substance
• the general form is A + X  AX
o 2Cu(s) + S(s)  Cu2S(s)
o 2Fe(s) + 3S(s)  Fe2S3(s)
o 2K(s) + Cl2(g)  2KCl
Decomposition Reactions
• a chemical change in which a single
compound breaks down into two or
more simple products.
• the general form is AX  A + X
o HgO(s) →
• 2HgO(s) → 2Hg(l) + O2(g)
o Zn(ClO3)2  ZnCl2 + 3O2
electricity
o H2O(l)
→ ?
• H2O(l)
• 2H2O(l)
→
→
H2(g) + O2(g)
2H2(g) + O2(g)
Single Replacement Reactions
• a chemical change in which one
element replaces a second element in a
compound
o metal will replace a metal, or a nonmetal
will replace a nonmetal
o general form is A + BX  AX + B
o Zn (s) + HCl (aq)  ?
(Zn is +2)
• Zn (s) + 2HCl (aq)  ZnCl2 (aq) + H2 (g)
• Zn more reactive that H so is oxidized (0 to +2)
and bonds with the negative Cl
• Al + Fe2O3  ?
o aluminum more reactive, will become and
ion, and will replace iron(III)
o 2Al + Fe2O3  2Fe + Al2O3
• Cl2 + NaI  ?
o Cl more reactive that I, will become an ion
and replace I
o Cl2 + 2NaI  2 NaCl + I2
Double Replacement Reactions
• an exchange of positive ions between two
chemicals
• general form is AX + BY  BX + AY
• reaction occurred if a gas, a precipitate, or
water is formed
• CuSO4 + Na2CO3  Na2SO4 + CuCO3
• NaOH + CuSO4  ?
o the Na+ and Cu2+ switch places.
o Na+ combines with SO42- to form Na2SO4.
o Cu2+ combines with OH- to form Cu(OH)2
o NaOH + CuSO4  Na2SO4 + Cu(OH)2
o 2NaOH + CuSO4  Na2SO4 + Cu(OH)2
• Na2CO3 + HCl  ?
o Na+1 combines with Cl-1 to form NaCl
o H+ combines with CO32- to form
H2CO3
o Na2CO3 + 2HCl  2NaCl + H2CO3
Combustion Reaction
• a type of combination reaction where
a substance reacts with oxygen
• often the burning of a fuel that
produces carbon dioxide, water, light,
and heat
• CH4 + O2  ?
o CH4 + O2  CO2 + H2O
o CH4 + 2O2  CO2 + 2H2O
Practice
• Classify each of the following as to
type:
• H2 + Cl2  2HCl
o combination
• Ca + 2H2O  Ca(OH)2 + H2
o single replacement
Practice
• 2CO + O2  2CO2
o combination and combustion
• 2KClO3  2KCl + 3O2
o decomposition
Practice
• FeS + 2HCl  FeCl2 + H2S
o double replacement
• Zn + HCl  ?
o single replacement
o Zn + 2HCl  ZnCl2 + H2