MATTER AND MATERIALS
GRADE 9
Learner Guide
NS Grade 9 Term 2 Learner Guide
1
MATTER AND MATERIALS
THE PERIODIC TABLE
1. What is the Periodic Table of Elements?
It is a chart that organizes all known elements based on their atomic number (the
number of protons in an atom).
(a) The elements are grouped based on their physical and chemical properties.
(b) It helps scientists predict the behavior of elements.
📌Example: If you know that Sodium (Na) is highly reactive, you can predict that Potassium
(K) will also be reactive because they belong to the same group.
2. Who Created the Periodic Table?
👨🔬 Dmitri Mendeleev (1869)
(a) He arranged elements based on atomic mass and grouped them by similar properties.
(b) He even predicted the existence of elements that were not yet discovered!
Example of a Prediction That Came True:
Mendeleev left a gap for Gallium (Ga), which was discovered later and matched his
prediction perfectly!
3. How is Each Element Represented?
Each element is placed in its own box with:
(a) Symbol – A short representation (e.g., H for Hydrogen, O for Oxygen).
(b) Atomic Number – Number of protons (e.g., Oxygen has 8 protons).
(c) Mass Number – Average atomic mass (e.g., Oxygen’s mass is about 16).
4. How are Elements Arranged?
(a) There are 7 periods and 18 groups in the Periodic Table.
(b) Elements in the same row have increasing atomic numbers.
(c) Elements in the same group have similar chemical properties.
(d) Knowing the group to which an element belongs helps us predict how an element will
react.
📌 Example: Sodium (Na) and Potassium (K) react violently with water because they are in
the same group.
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Answer the following questions:
1. What does the atomic number of an element represent?
A) The number of neutrons
B) The number of protons
C) The total number of particles in the nucleus
2. How are elements arranged in the Periodic Table?
A) By increasing atomic number
B) By increasing mass number
C) By their chemical reactivity
3. What is the difference between metals and non-metals?
A) Metals conduct electricity, and non-metals do not
B) Metals have low melting points, and non-metals have high melting points
C) Metals are usually gases, and non-metals are solid
4. Why are noble gases unreactive?
A) They do not contain neutrons
B) They have a full outer electron shell
C) They are very heavy elements
5. What do all elements in Period 2 have in common?
A) They have the same number of electron shells
B) They have the same number of protons
C) They are all highly reactive
6. How does the atomic number change across a period?
A) It increases
B) It decreases
C) It stays the same
7. What is the main property of alkali metals?
A) They are good insulators
B) They react violently with water
C) They are found only in compounds
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8. What are metalloids, and where are they found on the table?
A) They have properties of both metals and non-metals and are found between them
B) They are highly reactive elements found in Group 17
C) They are non-metals that conduct electricity
9. How does the reactivity of metals change down a group?
A) It increases
B) It decreases
C) It stays the same
10. Why is hydrogen placed separately from other groups?
A) It is a noble gas
B) It has only one electron but does not behave like Group 1 metals
C) It is the heaviest element
11. What happens to the size of atoms as you move across a period?
A) It increases
B) It decreases
C) It stays the same
12. Why is the mass number usually not a whole number?
A) The number of neutrons varies due to isotopes
B) It includes electrons in its calculation
C) The atomic number changes over time
13. How do scientists use the periodic table to predict new elements?
A) They mix different elements in experiments
B) They look for gaps and patterns in element properties
C) They assume all elements are already discovered
14. Why is silicon important in technology?
A) It is the main material in computer chips
B) It reacts violently with water
C) It is a metal used in construction
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Complete the following Periodic Table
Periodic Table of the Elements
1
3
Fill in the blanks with the atomic symbols of the first
20 elements. And then write the element names in
the blanks below.
2
Key:
4
5
6
7
8
9
10
13
14
15
16
17
18
Element name
Atomic number
symbol
11
12
19
20
scandium
titanium
vanadium
chromium
manganese
iron
Cobalt
21
22
23
24
25
26
27
Cr
Mn
Sc
Ti
V
47.867
zirconium
50.9415
niobium
40
41
42
43
rubidium
strontium
44.95591
yttrium
37
38
39
51.9961
54.93805
molybdenum technetium
Fe
Co
55.845
ruthenium
58.9332
Rhodium
44
45
nickel 28
Ni
germanium
arsenic
selenium
bromine
krypton
31
32
33
34
35
36
Cu
Zn
Ga
Ge
As
Se
Br
Kr
palladium
65.409
cadmium
69.723
indium
72.64
tin
74.9216
antimony
78.96
tellurium
79.904
iodine
83.798
xenon
46
47
48
49
50
51
52
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
87.62
88.90585
91.225
92.90638
95.94
[98]
101.07
(1)
__________________
(6)
__________________
(11)
(2)
__________________
(7)
__________________
(3)
__________________
(8)
(4)
__________________
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gallium
30
63.546
silver
85.4678
(5) __________________
zinc
29
58.6934
Rh
102.9055
copper
53
I
126.9045
Pd
Ag
Cd
In
Sn
Sb
Te
106.42
107.8682
112.411
114.818
118.710
121.760
127.60
__________________
(16)
__________________
(12)
__________________
(17)
__________________
__________________
(13)
__________________
(18)
__________________
(9)
__________________
(14)
__________________
(19)
__________________
(10)
__________________
(15)
__________________
(20) __________________
5
54
Xe
131.293
Uses of some elements:
1. Hydrogen - a primary constituent of water
2. Helium - many high-tech solutions, balloons for all sectors
3. Lithium - constituent of thermonuclear weapons;
4. Beryllium - many high-tech uses. Non-sparking drill bits/saw blades. Poisonous.
Constituent in nuclear weapons.
5. Boron - cleaning material
6. Carbon - charcoal, everyday fuel; graphite (pencils) and diamonds (best friends).
7. Nitrogen - keeps oxygen from burning the world up. Found in fertilizers, most
explosives, rocket fuels.
8. Oxygen - vital constituent of the air we breathe, component of fire, etc.
9. Fluorine – tooth pastes
10. Neon - used in signage
11. Sodium – in table salt, necessary to the body for nerve operation;
12. Magnesium - alloy component;
13. Aluminum - widely used for light metal structures.
14. Silicon – in almost all electronics
15. Phosphorous - proteins and in DNA itself, matches, etc.
16. Sulfur – in many explosives, for growth fertilizer;
17. Chlorine - bleaching/oxidization agent, disinfecting water or killing
microorganisms in water, etc.
18. Argon - component of the atmosphere;
19. Potassium - vital to nervous system function; important mineral for good plant
growth.
20. Calcium - component of most all plasters, animal bones, teeth and eggshells.
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Answer the following questions:
1. What is Hydrogen a primary constituent of?
A) Water
B) Rocks
2. Helium is commonly used for:
A) Filling balloons
B) Making explosives
3. Lithium is a key component of:
A) Batteries
B) Thermonuclear weapons
4. What is a key use of Beryllium?
A) Poisonous, used in nuclear weapons
B) Used in table salt
5. What is Boron commonly found in?
A) Cleaning materials
B) Fireworks
6. What is a common form of Carbon?
A) Diamonds
B) Glass
7. Why is Nitrogen important?
A) Found in fertilizers and explosives
B) Used in making jewellery
8. Oxygen is vital for:
A) Breathing
B) Lubrication
9. Fluorine is found in:
A) Toothpaste
B) Cooking oil
10. What is Neon primarily used for?
A) Signs
B) Fuel
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11. Sodium is essential for:
A) Nerve function
B) Glassmaking
12. Magnesium is used as:
A) An alloy component
B) A fuel source
13. Aluminum is widely used in:
A) Light metal structures
B) Fireworks
14. What is a key use of Silicon?
A) Electronics
B) Food seasoning
15. Phosphorus is found in:
A) DNA and proteins
B) Jewellery
16. Sulfur is commonly used in:
A) Explosives and fertilizers
B) Rubber production
17. Chlorine is primarily used for:
A) Disinfecting water
B) Making cloth
18. Argon is a component of:
A) The atmosphere
B) Human bones
19. Potassium is vital for:
A) Nervous system function
B) Rust prevention
20. Calcium is a key component of:
A) Bones, teeth, and eggshells
B) Plastic bags
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COMPOUND
a) A compound is a substance made of atoms from two or more different elements that are
chemically bonded together.
b) Examples include water (H₂O), carbon dioxide (CO₂), and salt (NaCl).
c) In every compound, the elements are always combined in a fixed ratio.
d) For example, in water, there are always two hydrogen atoms for every one oxygen atom
(H₂O).
e) This fixed ratio gives each compound unique properties that are different from the
individual elements.
EXAMPLES OF COMPOUNDS
ELEMENTS IN A COMPOUND
Complete the table below:
Name of the compound
A. Water
Elements in the compound
B. Carbon dioxide
C. Ammonia
D. Calcium carbonate (CaCO3)
E. Glucose (C6H12O6)
F. Table salt
G. Baking soda / Calcium bicarbonate
(NaHCO3)
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Chemical formula
NAMING A CHEMICAL COMPOUND
(a) There are mostly two part words in the name of a compound, e.g. MgO.
(b) The first part in the name is for the first element in the compound, e.g. CO 2 – Carbon
dioxide.
(c) The second part in the name is for the second element in the compound and the number
of the elements in that compound e.g. CO2 Carbon dioxide i.e. two oxygen’s.
(d) The following words are used in the naming to indicate the number of atoms “di” for
two, “tri” for three, “tetra” for four, “penta” for five, “hexa” for six, “hepta” for 7, “octa”
for 8, “nona” for nine and “deca” for 10.
(e) The first element is named as it is whereas the second element is slightly changed, e.g.
NaCl becomes sodium chloride.
(f) If a metal reacts with a non-metal, the metal comes first and the non-metal second, e.g.
MgO, the name would be Magnesium oxide (Magnesium is a metal and it comes first and
Oxygen is a nonmetal and it comes second) e.g. SiO2 – silicon dioxide, NaCl – sodium
chloride, NaI – sodium iodide, NaF – sodium fluoride, CuO – Copper oxide, Fe2O3 – iron
oxide, MgO – magnesium dioxide.
(g) For Simple Binary Compounds (Two Elements Only). The second element’s name
ends in "-ide" instead of its full name, e.g
(i) NaCl
Sodium chloride (Chlorine
Chloride)
(ii) MgO
Magnesium oxide (Oxygen
Oxide)
(iii) CO₂
Carbon dioxide (Oxygen
Oxide)
(iv) H₂S
Hydrogen sulfide (Sulfur
Sulfide)
(h) If the compound has two non-metals, e.g. CO2 the first part is for the element that is
more to the left, in this case C or the one lying higher than the other and the ending
changes to –ide, e.g. CO2 - carbon dioxide, SO2 sulfur dioxide, SO3 - sulfur trioxide, etc.
(i) If a metal reacts with two non-metals and one of them is oxygen the suffix (last part)
becomes –ate, e.g. KNO3 is potassium nitrate, Na2CO3 is sodium carbonate.
(j) Another rule concerns transitional elements which have more than one ion, so that has
to be indicated in the name, e.g. Iron (II) oxide or Iron (III) oxide.
(k) Some compounds have polyatomic ions.
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Polyatomic ion
Formula
Example
Name of the compound
Sulfate
SO42-
MgSO4
Magnesium sulfate
Nitrate
NO-3
KNO3
Potassium nitrate
Phosphate
PO3-4
(NH4)3PO4
Ammonium phosphate
Carbonate
CO2-3
CaCO3
Carbon carbonate
Ammonium
NH4+
NH4Cl
Ammonium Chloride
Answer the following questions:
1. In the compound MgO, what are the two elements?
A) Magnesium and Oxygen
B) Magnesium and Carbon
C) Manganese and Oxygen
2. What is the name of the compound MgO?
A) Magnesium oxide
B) Magnesium dioxide
C) Magnesium peroxide
3. Which element is a metal and which one is a non-metal in the compound MgO?
A) Magnesium is a non-metal, Oxygen is a metal
B) Magnesium is a metal, Oxygen is a non-metal
C) Both Magnesium and Oxygen are metals
4. What do the words “di”, “tri”, “tetra”, “penta”, “hexa”, “hepta”, “octa”, “nona” and
“deca” indicate in compound naming?
A) The type of bonding in the compound
B) The number of atoms of an element in the compound
C) The charge of the compound
5. What is the name of the compound NaCl?
A) Sodium chloride
B) Sodium chlorine
C) Sodium chlorate
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6. What do we observe in the name of the compound NaCl?
A) The second element’s name changes to "-ide"
B) The first element is named last
C) The name always ends in "-ate"
7. What is the name of the compound MgCl₂?
A) Magnesium chlorate
B) Magnesium chloride
C) Magnesium chlorite
8. Which rule is followed when naming a compound that has two non-metals?
A) The first element keeps its name, and the second element’s name ends in "-ide"
B) The first element is always Oxygen
C) The second element is always named first
9. What are the correct names for NaCl, CuO, MgO, NaF, SiO2, and SO₂?
A) Sodium chloride, Copper oxide, Magnesium oxide, Sodium fluoride, Silicon oxide, Sulfur
dioxide
B) Sodium chloride, Copper oxygen, Magnesium oxygen, Sodium fluoride, Silicon dioxide,
Sulfur oxygen
C) Sodium chloride, Copper monoxide, Magnesium fluoride, Sodium oxide, Silicon dioxide,
Sulfur oxide
10. Are the elements in NaCl, CuO, MgO, NaF, SiO2, and SO₂ metals or non-metals?
A) All are non-metals
B) Some are metals, and some are non-metals
C) All are metals
11. What happens to the name if a metal reacts with two non-metals, and one of them is
oxygen?
A) The name of the compound ends in "-ate"
B) The second element’s name remains unchanged
C) The compound is always an acid
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12. What are the names of the compounds KNO₃ and Na₂CO₃?
A) Potassium nitrate and Sodium carbonate
B) Potassium nitrite and Sodium carbonite
C) Potassium nitrogen oxide and Sodium carbon dioxide
13. What is the correct name for SO₃?
A) Sulfur trioxide
B) Sulfur oxide
C) Sulfur dioxide
14. What is the rule for naming transition metals with multiple oxidation states?
A) A Roman numeral is used to indicate the charge of the metal
B) The second element always ends in "-ate"
C) The name of the metal changes depending on its charge
15. What is the correct name for Fe₂O₃?
A) Iron (II) oxide
B) Iron (III) oxide
C) Iron trioxide
i. Complete the table below:
Polyatomic ion
Formula
Example
Sulfate
SO42-
MgSO4
Nitrate
NO-3
KNO3
Phosphate
PO3-4
(NH4)3PO4
Carbonate
CO2-3
CaCO3
Ammonium
NH4+
NH4Cl
Name of the compound
CHEMICAL REACTIONS: CHEMICAL EQUATIONS TO REPRESENT REACTIONS

When we represent a chemical reaction in terms of chemical formulae (symbols), it is
called a chemical equation. C + O2
CO2
(a) Chemical reactions are usually represented with symbols:
(b) What is a chemical reaction? A reaction or chemical reaction is a chemical change
which results in the formation of new substances.
(c) When a chemical equation is expressed in words, it is called a word equation.
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(d) When an equation is expressed using pictures or even models, it is a picture
equation.
(e) When symbols are used to represent chemical reaction, it is known as symbol
equation.
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Answer the following questions:
1. In the diagram above, what type of equations are represented by A, B and C?
___________________________________________________________________________
___________________________________________________________________________
___________________________________________________________________________
2. In equation B, how many oxygen atoms are shown on the left of the equation?
________________________________________________________________________
3. How many carbon atoms (C) are on the right of the equation?
________________________________________________________________________
4. Write a word equation for: 2H2 + O2
2H2O
_______________________________________________________________________________
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IDENTIFYING ATOMS
 Let us take note of the atoms in each of the following:
CuCO3

Cu (Copper)

C (Carbon) and

(Oxygen)
2(NH4)2CO3

N (Nitrogen)

H(Hydrogen)

C (Carbon) and

(Oxygen)
2CaCO3

Ca (Calcium)

C (Carbon) and

(Oxygen)
CALCULATING THE NUMBERS
CuCO3

Cu = 1 Cu

C = 1 C and

3xO=3O
2(NH4)2CO3

2 x 2 x N = 4N

2 x 2 x 4 x H = 16H ,

2 x C = 2 and

2x3xO=6O
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2CaCO3

2 x Ca = 2 Ca

2 x C = 2 C and

2x3xO=6O
ACTIVITY
Calculate the atoms in the following compounds:
(a) 3CaCO3
_________________________________________________________________________________________________________
(b) 3(NH4)2CO3
_________________________________________________________________________________________________________
(c) 2CuCO3
____________________________________________________________________________________________________ _____
(d) ZnSO4
_________________________________________________________________________________________________________
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BALANCING A GIVEN CHEMICAL EQUATION
H2 + Cl2
HCl
Identify the atoms in the equation and write them in the table
On the left
How many?
On the right
How many?
H
2
H
1
Cl
2
Cl
1
(a) A balanced equation must have the same number of atoms on the left and on the
right. When balancin g a chemical equation, you can ONLY change the coefficient and
not the bonding ratio.
(b) What is a co-efficient? It is a the number that comes before a variable in
Mathematics.
(c) In chemistry a coefficient is a number that comes before a reactant(s) or produt(s).
On the left
How many?
On the right
How many?
H
2
H
2
Cl
2
Cl
2
(d) There must be two hydrogens on the right, put a cofficient of 2 before the HCl to
make it 2HCl.
(e) Now looking at the table, the equation is balanced because it has the same number of
atoms on the left and right.
(f) Now the equation is balanced.
Balanced chemical equations:

4Fe + 3O2
2Fe2O3 (Brown rusty coating)

2Mg + O2
2MgO (White powder)

Cu + O2
CuO (Black solid)
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Simple rules to remember when balancing equations:
1. Law of conservation of matter states that matter cannot be created or destroyed
during a chemical reaction but can change from one form to another.
2. Write the correct chemical equation.
3. Identify the atoms or ions on both sides (left and right) of the equation.
4. After identifying, count how many of each on both sides of the equation.
5. If you have polyatomic ions that are the same on both sides, count them as a single
unit, e.g. H2SO4, CaCO3 etc.
6. Balance those that are not balanced by using a coefficient.
7. Oxygen and hydrogen can be balanced later.
8. Keep the coefficient at its lowest possible whole number ratio.
Answer the following questions:
1. What does the law of conservation of matter state?
a) Matter can be created and destroyed.
b) Matter cannot be created or destroyed but can change forms.
c) Matter can disappear in a chemical reaction.
2. In the chemical equation H₂ + Cl₂ → HCl, what is missing to make it balanced?
a) A coefficient of 2 before HCl.
b) A coefficient of 2 before Cl₂.
c) A coefficient of 3 before H₂.
3. What is a coefficient in a chemical equation?
a) A number placed before a reactant or product to balance an equation.
b) A subscript that represents the number of atoms in a molecule.
c) A symbol that represents an element.
4. Which of the following is a balanced chemical equation?
a) H₂ + O₂ → H₂O
b) 2H₂ + O₂ → 2H₂O
c) H₂ + 2O₂ → 2H₂O
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5. Why do we balance chemical equations?
a) To satisfy the law of conservation of mass.
b) To make equations look symmetrical.
c) To change the identity of the reactants.
6. Which of the following can be changed to balance an equation?
a) The coefficients
b) The subscripts
c) The chemical symbols
7. In the reaction 2Mg + O₂ → 2MgO, how many oxygen atoms are present on the
left?
a) 1
b) 2
c) 4
8. What should be balanced last when balancing an equation?
a) Hydrogen and oxygen
b) The metal atoms
c) The coefficients
9. What does the number “4” represent in 4Fe + 3O₂ → 2Fe₂O₃?
a) Four atoms of iron react with oxygen.
b) Four molecules of iron oxide are produced.
c) The atomic number of iron.
10. What is the balanced form of the equation Cu + O₂ → CuO?
) 2Cu + O₂
2CuO
b) Cu + O₂
Cu₂O
c) Cu + 2O₂
CuO
11. Which of the following is a rule for balancing chemical equations?
a) Always start by balancing hydrogen and oxygen.
b) Use coefficients to balance the number of atoms on both sides of the equation.
c) Change the subscripts to balance the equation.
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12. In the equation 4Fe + 3O₂
2Fe₂O₃, how many iron atoms are there on the
right side of the equation?
a) 4 iron atoms
b) 6 iron atoms
c) 2 iron atoms
Balance the following equations:
1. H2 + O2
H2O __________________________________________________
2. Al + O2
Al2O3 ___________________________________________________________________________
3. C3H8 + O2
CO2 + H2O ____________________________________________
4. Al(NO3)3 + NaOH
Al(OH)3 + NaNO3 _________________________________________________
5. N2 + H2 (g)
NH3 _________________________________________________________________________
6. K2O + H2O (g)
KOH _____________________________________________
7. H2O2(g)
H2O + O2 ______________________________________________________________________
8. Fe + O2
Fe2O3 ________________________________________________
9. Mg + O2
MgO _______________________________________________
10. Cu + O2
CuO _______________________________________________
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REACTIONS OF METALS WITH OXYGEN
THE GENERAL REACTION OF METALS WITH OXYGEN
(a) Some metals burn in the presence of oxygen.

Certain metals react with oxygen when exposed to it and catch fire.
(b) When a metal reacts with oxygen, it forms a metal oxide.

This reaction creates a compound called a "metal oxide."
(c) The general equation for the reaction between a metal and oxygen is:

o
metal + oxygen
metal oxide
This shows that a metal combines with oxygen to form a metal oxide.
(d) The name of a metal oxide is formed by combining the name of the metal with
the word "oxide."

For example, when iron reacts with oxygen, it forms iron oxide.
(e) Let’s look at some examples:


Potassium oxide: Potassium (the metal) reacts with oxygen, and we add the
word "oxide."
Calcium oxide: Calcium (the metal) reacts with oxygen, and we add "oxide" at
the end.
(f) When iron reacts with oxygen, it forms iron oxide.

The equation is:
iron + oxygen
Fe + O₂
iron oxide
Fe₂O₃
(g) Magnesium reacts with oxygen to form magnesium oxide.

The equation is: magnesium + oxygen
Mg + O₂
MgO
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magnesium oxide
Answer the following questions:
1. What happens when a metal reacts with oxygen?
a) It forms a non-metal oxide.
b) It forms a metal oxide.
c) It forms a metal salt.
2. Which of the following is the general equation for the reaction between a metal
and oxygen?
a) metal + hydrogen
metal hydride
b) metal + oxygen
metal oxide
c) metal + water
metal hydroxide
3. What does the name of a metal oxide consist of?
a) The name of the metal followed by "oxide."
b) The name of the metal followed by "acid."
c) The name of the metal followed by "salt."
4. What is the product when potassium reacts with oxygen?
a) Potassium chloride
b) Potassium oxide
c) Potassium sulfide
5. What does the word "oxide" mean in chemical terms?
a) It refers to a compound containing oxygen and hydrogen.
b) It refers to a compound containing oxygen and a metal.
c) It refers to a compound containing oxygen and carbon.
6. When iron reacts with oxygen, what does it form?
a) Iron sulfate
b) Iron oxide
c) Iron chloride
7. What is the result when magnesium reacts with oxygen?
a) Magnesium hydroxide
b) Magnesium oxide
c) Magnesium sulfide
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8. Which of these elements reacts with oxygen to form magnesium oxide?
a) Calcium
b) Magnesium
c) Sodium
9. What is the name of the compound formed when calcium reacts with oxygen?
a) Calcium sulfate
b) Calcium oxide
c) Calcium chloride
10. What type of compound is formed when a metal reacts with oxygen?
a) Non-metal oxide
b) Metal oxide
c) Metal sulfate
11. Which of the following is true about the reaction between metals and oxygen?
a) The reaction produces a non-metal oxide.
b) The reaction forms a salt compound.
c) The reaction forms a metal oxide.
12. In the equation: Fe + O₂
Fe₂O₃, what does Fe₂O₃ represent?
a) Iron sulfate
b) Iron chloride
c) Iron oxide
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FORMATION OF RUST
1. What is Rust?
o
Rust is a reddish-brown substance that forms when iron reacts with oxygen and
water.
2. When Does Rust Form?
o
For rust to occur, both water and oxygen must be present.
3. Where Does Rust Form?
o
Rust mainly affects iron and steel because they contain iron.
4. Rust is a Type of Iron Oxide
o
The chemical reaction between iron, oxygen, and water produces iron oxide (rust).
5. Rust Weakens Metal
o
Over time, rust breaks down iron and steel, making them brittle and weak.
6. Rust is Worse in Salty Water
o
Sea water speeds up rusting about five times faster than fresh water.
7. How Does Salt Increase Rust?
o
Salt in water causes electrolytic reactions, which speed up the rusting process.
8. Rust Affects Everyday Objects
o
Cars, bridges, tools, and pipes can all be damaged by rust if not protected.
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Ways to Prevent Rust
(a) Painting and Coating - Creates a protective layer to keep moisture and oxygen away. Commonly used on bridges, gates, and vehicles to prevent rust.
(b) Electroplating with Chromium or Zinc - Coating iron and steel with a thin layer of
chromium or zinc, metals that do not rust. - Uses an electroplating technique, which is
a form of electrolysis.
(c) How Electroplating Works - The metal is placed in a chromium or zinc salt solution. - An
electric current is passed through, coating the metal with chromium or zinc. - This
protective layer prevents exposure to oxygen and water.
(d) Benefits of Electroplating (1) Prevents rust and increases the lifespan of metal objects.
(2) Used in car parts, tools, kitchen appliances, and machinery. (3) Enhances
appearance and durability of metals.
Answer the following questions:
1. What is rust?
a) A black coating that forms on iron
b) A reddish-brown substance that forms when iron reacts with oxygen and water
2. What two elements must be present for rust to form?
a) Water and oxygen
b) Iron and nitrogen
3. Which type of metal is most affected by rust?
a) Aluminum
b) Iron and steel
4. What is the chemical composition of rust?
a) Iron oxide
b) Iron chloride
5. How does rust affect metal structures?
a) It strengthens them over time
b) It weakens them, making them brittle and fragile
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6. Why does rusting happen faster in salt water?
a) Salt water increases electrolytic reactions
b) Salt water slows down oxidation
7. Which of these objects is most at risk of rusting?
a) A plastic chair
b) A steel bridge
8. What is electroplating used for?
a) To remove rust from metals
b) To coat metals with a protective layer of chromium or zinc
9. Which method helps prevent rust?
a) Painting iron and steel to keep out moisture and oxygen
b) Exposing iron to high humidity
10. What is the purpose of electroplating with zinc or chromium?
a) To make the metal heavier
b) To protect the metal from rust
11. Why does rusting weaken metal over time?
a) Because the rust forms a protective layer that strengthens the metal
b) Because rust causes the metal to flake away, reducing its strength and durability
12. Why is it important to prevent rust in everyday objects like vehicles, tools, and
bridges?
a) To maintain their durability and prevent structural damage
b) Because rust makes them look more appealing
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REACTIONS OF NON-METALS WITH OXYGEN
The general reaction of non-metals with oxygen
(a) Non-metals react with oxygen to form non-metal oxides.
(b) The name of the product will have the non metal name and the word “oxide”, e.g.
carbon dioxide.
(c) When a non-metal burns in excess oxygen or react with oxygen, the general equation is
always: non-metal + oxygen non-metal oxide
(d) Carbon (sometimes in a form of coal) and sulphur are some of the non-metals reacting
with oxygen.
(e) Coal is a form of carbon used as fuel for energy and is one of the primary fossil fuels that
humans use to generate electricity.
coal + oxygen
carbon dioxide
C + O2
CO2
(f) Sulfur is burned to produce sulphur compounds such as SO 2 and SO3 used to produce
sulphuric acid, fertilizers and to control pests, fungi and mould.
Sulphur + oxygen sulphur
dioxide
S + O2
SO2
Write the chemical equations for:
1. carbon + oxygen
carbon dioxide
2. sulphur + oxygen
sulphur dioxide
3. Balance the following equation: P + O2
P2O5
4. When a non-metal reacts with oxygen the product of the reaction is a
5. For the reaction between oxygen and carbon:
(a) Write the word equation
(b) Draw the picture equation
(c) Write the chemical equation
6. Write the chemical equation for the reaction between sulphur and oxygen.
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ACIDS & BASES, AND pH VALUE
The concept of pH value
1. What is pH?
a) A measure of how cold or hot a substance is.
b) A measure of how acidic or basic a substance is.
c) A measure of the density of a substance.
2. Which pH range corresponds to acids?
a) 0 - 7
b) 1 - 6
c) 7 - 14
3. What pH range corresponds to bases?
a) 0 - 7
b) 7 - 14
c) 1 - 6
4. What is the pH of a neutral substance?
a) 0
b) 7
c) 14
5. Which of the following is used to identify acids and bases?
a) Thermometer
b) Chemical indicators
c) Ruler
6. What color does a universal indicator turn in an acidic solution?
a) Green
b) Blue
c) Yellow, orange, or red
7. What color does a universal indicator turn in a basic solution?
a) Yellow
b) Purple or blue
c) Red
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8. What color does a universal indicator turn in a neutral solution?
a) Green
b) Yellow
c) Blue
9. Which of the following is a strong acid?
a) Lemon juice (pH 2)
b) Water (pH 7)
c) Baking soda (pH 9)
10. Which of the following is a strong base?
a) Vinegar (pH 4)
b) Ammonia solution (pH 11)
c) Orange juice (pH 3)
Long Answer Questions:
1. Explain how the pH scale works and what the difference between acids, bases, and
neutral substances is.
2. Describe how chemical indicators, such as the universal indicator, can be used to identify
whether a substance is acidic, basic, or neutral.
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REACTIONS OF ACIDS WITH BASES: PART I
NEUTRALISATION AND pH
1. What is a Neutralization Reaction?
o
When acids and bases react together, it is called a neutralization reaction.
o
A neutralization reaction results in the production of water and a salt, and it makes the
substance more neutral (pH around 7).
2. Reaction Between Acids and Bases:
o
Base + Acid → Neutralized solution
o
A base reacts with an acid to make the solution less acidic (closer to neutral).
o
An acid reacts with a base to make the solution less basic (closer to neutral).
3. Common Acids Used in the Laboratory:
o
Sulfuric acid (H₂SO₄): A strong acid commonly used in laboratories.
o
Hydrochloric acid (HCl): Another strong acid frequently used in laboratory experiments.
4. Effect of Acid and Base Strength:
o
After a neutralization reaction, the resultant pH will depend on the strength of the acid
and base used.
o
Stronger acids and bases will lead to a stronger neutralizing effect.
5. Non-metal Oxides:
o
Non-metal oxides tend to be acidic and have low pH values. (For example, carbon dioxide
forms carbonic acid when dissolved in water.)
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6. Metal Oxides, Hydroxides, and Carbonates:
o
Bases (with high pH) include:
(a) Metal oxides such as Iron oxide (Fe2O3), Magnesium oxide MgO, etc.),
The name has the name of the metal and the word “oxide”.
(b) Metal hydroxides: Metal hydroxide such as Sodium hydroxide (NaOH), Calcium
hydroxide (CaOH, etc.
The name has the name of the metal and the word “hydroxide”
(c) Metal carbonates Metal carbonates such as Calcium carbonate (CaCO3), Sodium
carbonate (NaCO3, etc.

The name has the name of the metal and the word “carbonate”.
These substances can neutralize acids and raise the pH of acidic solutions.
They have a basic pH or pH greater than 7:
Answer the following questions:
1. What is a neutralization reaction?
a) When acids and bases react together, producing water and salt
b) When acids react with water to form a gas
c) When bases react with water to form a gas
2. What does a neutralization reaction produce?
a) Water and a gas
b) Water and a salt
c) Water and oxygen
3. What happens when a base reacts with an acid in a neutralization reaction?
a) The solution becomes more acidic
b) The solution becomes less acidic (closer to neutral)
c) The solution becomes more basic
4. Which of the following is a common acid used in laboratories?
a) Hydrochloric acid (HCl)
b) Sodium hydroxide (NaOH)
c) Calcium carbonate (CaCO₃)
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5. What determines the strength of the resultant pH after a neutralization reaction?
a) The temperature of the acid and base
b) The strength of the acid and base used
c) The volume of the acid and base used
6. What is a non-metal oxide that tends to be acidic?
a) Magnesium oxide (MgO)
b) Carbon dioxide (CO₂)
c) Sodium hydroxide (NaOH)
7. Which of the following are examples of metal hydroxides?
a) Magnesium oxide (MgO)
b) Calcium carbonate (CaCO₃)
c) Sodium hydroxide (NaOH)
8. What is the general name of substances that can neutralize acids and raise the pH
of solutions?
a) Non-metal oxides
b) Bases (metal oxides, hydroxides, and carbonates)
c) Acids
Long Answer Questions:
1. Explain what happens during a neutralization reaction between an acid and a base.
What are the products of this reaction, and how does it affect the pH of the
solution?
2. Describe the role of common acids like sulfuric acid (H₂SO₄) and hydrochloric acid
(HCl) in laboratory experiments. How do these acids react with bases in
neutralization reactions?
3. How do non-metal oxides like carbon dioxide form acidic solutions when dissolved in
water? Explain the chemical process and the resulting pH change.
4. Discuss the role of metal oxides, hydroxides, and carbonates in neutralizing acids.
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Reactions of acids with bases: Part II
The general reaction of an acid with a metal oxide (base)
1. What are Metal Oxides?
(a) When metals react with oxygen, they form metal oxides.
(b) These oxides are typically basic in nature.
2. Acids react with metal oxides (base) to produce salt and water.
3. The type of salt depends on the acid and metal oxide used.
4. The general eqation is always: Acid + metal oxide
Example: Hydrochloric acid + magnesium oxide
2HCl
+
Acid
MgO
Metal oxide
MgCl2
Salt
salt + water.
magnesium chloride + water
+
H2 O
Water
Application:
(a) Sulfur dioxide gas released when burning coal and oil for energy production, sulphur
dioxide is also released into the atmosphere.
(b) In the atmosphere, sulphur dioxide reacts with water to form sulphurous acid.
(c) The acid reacts with oxygen form sulphuric acid which is eventually deposited on the
Earth surface as acid rain.
(SO2 + H2O
H2SO3)
(d) Acid rain affect water in rivers, dams, for instance and affect plants, animals,
buildings, etc.
(e) Farmers use limestone (CaCO3) to neutralise an acidic soil making it more suitable for
plant growth.
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Answer the following questions:
1. What is a Metal Oxide?
a) The product that forms from the reaction of a metal with oxygen is a metal oxide.
b) These oxides are typically acidic in nature.
c) Metal oxides do not react with acids.
2. What do acids produce when they react with metal oxides?
a) Gas and salt
b) Salt and water
c) Salt and oxygen
3. What determines the type of salt produced in a reaction between an acid and a
metal oxide?
a) The type of acid and metal oxide used.
b) The temperature of the reaction.
c) The amount of oxygen present in the reaction.
4. What is the general equation for the reaction between an acid and a metal oxide?
a) Acid + Metal oxide
Salt + Oxygen
b) Acid + Metal oxide
Salt + Water
c) Acid + Metal oxide
Water + Gas
5. What is the product of the reaction between hydrochloric acid and magnesium
oxide?
a) Magnesium chloride and water
b) Magnesium sulfate and oxygen
c) Magnesium hydroxide and salt
6. Which of the following is a result of burning sulfur-containing materials like coal
and oil?
a) Release of carbon dioxide
b) Release of sulfur dioxide
c) Release of nitrogen oxide
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7. What happens when sulfur dioxide reacts with water in the atmosphere?
a) It forms sulfuric acid.
b) It forms sulfurous acid.
c) It forms nitric acid.
8. What is the impact of sulfur dioxide in the atmosphere?
a) It reacts with water to form sulfurous acid.
b) It reacts with water and oxygen to form sulfuric acid, which contributes to acid
rain.
9. How does acid rain affect the environment?
a) It improves the quality of water in rivers and lakes.
b) It damages plants, animals, and buildings.
c) It helps plants grow better by neutralizing soil acidity.
10. What is the role of limestone (CaCO₃) in farming?
a) It makes soil more acidic.
b) It neutralizes acidic soil to make it suitable for plant growth.
c) It helps plants grow in alkaline soil.
11. What causes acid rain to form?
a) Nitrogen oxide reacting with oxygen.
b) Sulfur dioxide reacting with water and oxygen to form sulfuric acid.
c) Carbon dioxide reacting with water.
12. Which of the following is true about the effects of acid rain?
a) Acid rain is beneficial to all plants and animals.
b) Acid rain can harm buildings, water sources, and ecosystems.
c) Acid rain does not affect buildings and ecosystems.
Long Answer Questions:
1. Explain the general process of how an acid reacts with a metal oxide. What are the
products of this reaction?
2. Describe how acid rain is formed and what its environmental impacts are. How do
acid rain and its effects pose challenges to ecosystems and infrastructure?
3. Explain how limestone (CaCO₃) is used in agriculture and its importance for plant
growth.
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