CAMBRIDGE IGCSE™ CHEMISTRY: WORKSHEET 4
Name
Date
4: Chemical formulae and equations
1 Complete the following table.
Formula
Number of atoms
Relative formula mass (Mr)
NaCl
FeBr3
MgCl2
NaNO3
Mg(OH)2
Al2(SO4)3
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CAMBRIDGE IGCSE™ CHEMISTRY: WORKSHEET 4
2 Complete the following table. (Atoms of each element have a combining power, sometimes
referred to as their valency. Note that the term valency is not required knowledge.)
Elements
Valences of elements
Formula of compound
Hydrogen
Chlorine
H=1
Cl = 1
HCl
Hydrogen
Bromine
H=
Br =
Carbon
Hydrogen
C=
H=
Sulfur
Fluorine
S=
F=
Phosphorus
Hydrogen
P=
H=
Hydrogen
Oxygen
H=
O=
Hydrogen
Sulfur
H=
S=
Carbon
Oxygen
C=
O=
Boron
Fluorine
B=
F=
3 Use the following table to work out the formulae of ionic compounds from their elements.
Metal
Metal ion
Non-metal
Non-metal ion
Na (GP I)
Na+
Cl2 (GP VII)
Cl−
Li (GP I)
Li+
Br2 (GP VII)
Br−
Ca (GP II)
Ca2+
I2 (GP VII)
I−
Mg (GP II)
Mg2+
O2 (GP VI)
O2−
Al (GP III)
Al3+
N2 (GP V)
N3−
Cambridge IGCSE™ Chemistry – Scholier © Cambridge University Press 2021
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CAMBRIDGE IGCSE™ CHEMISTRY: WORKSHEET 4
a Sodium and bromine
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b Calcium and iodine
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c Magnesium and oxygen
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d Sodium and oxygen
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e Aluminium and oxygen
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f
Lithium and nitrogen
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4 Turn the following descriptions into word equations.
a Hydrogen and oxygen react together to make water.
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b Nitrogen and oxygen react together to make nitrogen oxide.
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c Sulfuric acid is neutralised by sodium hydroxide. It forms sodium sulfate and water.
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d Magnesium chloride is formed when magnesium reacts with hydrochloric acid. Hydrogen is
also formed.
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Cambridge IGCSE™ Chemistry – Scholier © Cambridge University Press 2021
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CAMBRIDGE IGCSE™ CHEMISTRY: WORKSHEET 4
5 Balance these symbol equations (some may already balance).
a Mg + O2 à MgO
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b K + Cl2 à KCl
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c Li + O2 à Li2O
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d Mg + H2SO4 à MgSO4 + H2
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e Na + H2O à NaOH + H2
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f
Ba + HCl à BaCl2 + H2
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g Sr(OH)2 + HCl à SrCl2 + H2O
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h MgO + H2SO4 à MgSO4 + H2O
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i
Be(OH)2 + HNO3 à Be(NO3)2 + H2O
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Cambridge IGCSE™ Chemistry – Scholier © Cambridge University Press 2021
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