ZNOTES.ORG
UPDATED TO 2023-25 SYLLABUS
CAIE IGCSE
CHEMISTRY
SUMMARIZED NOTES ON THE THEORY SYLLABUS
,CAIE IGCSE CHEMISTRY
Boiling Evaporation
1. States of Matter boiling occurs throughout the evaporation only occurs at the
liquid surface
boiling is a relatively faster
1.1. Solids, liquids and gases evaporation is a slow process
process
States of matter are the different forms in which matter
can exist Condensation
The three states of matter are: Solid, liquid and gases
Condensation is the process in which a gas converts into a
Characteristics of Solids, liquids and gases -→ liquid. It happens at the same temperature as the boiling
SOLIDS LIQUIDS GASES point
take the take the As temperature decreases, the energy of particles will
have a
SHAPE shape of their shape of their decrease, making it move more slowly.
definite shape
container container Condensation and Freezing are both energy given out
moderate to reaction.
DENSITY high low
high
don’t have a Freezing and melting (endothermic
have a fixed have a fixed fixed volume -
VOLUME processes)
volume volume expand to fill
the container
1. Melting is the process in which a solid converts to a
non-fluid in
FLUIDITY fluid in nature fluid in nature liquid. It happens at a set temperature called the
nature
melting point
closely- 2. Freezing is the process in which a liquid coverts to a
closely-
packed solid. It happens at the same temperature as the
packed presence of
INTER- together, melting point
together, large, inter-
PARTICULAR barely any
barely any molecular
SPACES inter-
molecular
inter- spaces 1.3. Cooling and Heating Curves
molecular
spaces (Extended)
particles are
immobile, particles are particles are Cooling curves
PARTICULAR however, they able to move mobile and
MOVEMENT can vibrate past one move 1. On cooling, the particles of a gas move slower and
about their another randomly slower and the gas contracts
fixed positions 2. The particles are now closer together and inter-
particles are molecular bonds start to form between them once the
particles are particles are
PARTICULAR arranged condensation point is reached
arranged arranged
ARRANGEMENT regularly in a 3. The temperature of the substance stops falling; the
irregularly irregularly
lattice energy released by bond formation cancels out the
energy lost due to cooling
4. Once all the gas has turned into liquid, the
1.2. Boiling and Evaporation temperature starts to fall again and the liquid begins
to contract until the freezing point is reached
Boiling and Evaporation are (endothermic processes):
5. At the freezing point, inter-molecular bonds between
Boiling and evaporation are processes which involve the the liquid molecules start to develop to form a solid
conversion of a liquid into a gas. 6. At the freezing point, the temperature remains
Both processes allow molecules to move further apart constant until all of the liquid has solidified since, the
from each other. energy released due to bond formation cancels out
the energy lost due to cooling
Boiling Evaporation
The following curve is obtained if this phenomenon is plotted -
evaporation occurs at any
boiling happens at a set the cooling curve -→
temperature below the boiling
temperature called the boiling
point and above the freezing
point
point (liquid)
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,CAIE IGCSE CHEMISTRY
1.4. Effects of Temperature and
Pressure on Gas
Gases are compressible in nature. By changing the pressure
acting on them, their volume may be influenced.
1. An increase in external pressure produces a
contraction (decrease) in volume. The gas is said to be
compressed
2. A fall in external pressure produces an expansion
(increase) in volume. The gas is said to be
decompressed
The volume of gases may also be influenced by temperature.
The temperature of a gas affects its internal pressure and
thereby its volume.
1. When temperature increases, the gas molecules have
increased kinetic energy and hit the walls of their
Heating Curves container more often and with greater force. This
causes an increase in internal pressure and an
1. On heating, the particles of a solid start to vibrate increase in volume.
faster and faster in their mean positions and the solid 2. When temperature decrease, the gas molecules have
begins to expand decreased kinetic energy and hit the walls of their
2. Once the melting point is reached, the inter-molecular container less often and with attenuated force. This
bonds between the particles begin to breakdown causes a decrease in internal pressure and a
3. The temperature of the substance at this point decrease in volume.
remains constant until all the solid has turned into a
liquid because the energy received by the system is In conclusion -→
cancelled out by the energy used to break
intermolecular bonds 1. Temperature and volume of gases are directly
4. Once all the solid has turned to liquid, the temperature proportional
starts to rise again and the liquid begins to expand 2. External pressure and volume of gases are inversely
proportional
until the boiling point is reached
5. At the boiling point, the intermolecular bonds between
the liquid molecules start to break down to form gas 1.5. Diffusion
6. At the boiling point, the temperature of the substance
remains constant until all of the liquid has vaporized Diffusion, the net movement of particles from a region of
since, the energy absorbed by the substance is higher concentration to a region of lower concentration, as a
cancelled by the energy used for breakdown of result of their random movement until equilibrium is reached
intermolecular bonds The rate of diffusion is most rapid in gases > liquids > solids
The following curve is obtained if this phenomenon is
plotted - the heating curve -→ 1.6. Effect of Relative Molecular Mass in
Diffusion (Extended)
The rate at which gases diffuse is different and is
dependent on the mass of the gas molecules.
At the same temperature, molecules that have a lower
mass move, on average, faster than those with a higher
mass.
The HCl and NH3 experiment
The experiment involved placing a cotton wool plug soaked in
hydrochloric acid (HCl) at one end of a glass tube and a
cotton wool plug soaked in ammonia (NH3) at the other end.
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, CAIE IGCSE CHEMISTRY
The tube was left undisturbed for a period of time, during Subatomic particle Relative Mass Relative Charge
which the gases diffused towards each other. The rate of electron 1/1840 -1
diffusion was measured by observing the distance travelled
by each gas after a fixed time. It was found that ammonia,
Since electrons and protons have opposing and equal
with a lower molecular mass, diffused faster than
charges, the atom’s overall charge is neutral.
hydrochloric acid, which has a higher molecular mass.
Neutrons have the purpose of holding the nucleus
together. The larger the nucleus gets, more are the
Conclusion: Ammonia has a smaller Mr than hydrochloric
neutrons required to hold the nucleus together
acid so ammonia has a greater rate of diffusion. Therefore,
the white ring of ammonium chloride forms near the
hydrochloric acid.
2.3. Proton Number and Nucleon
Number
2. Atoms, Elements and
The proton number (atomic number) is the number of
Compounds protons in the nucleus of an atom.
It is unique to each element. It is denoted with the letter
Atom: The smallest particle of matter made of protons, “Z”. For an atom which is neutral in nature, the number of
protons and the number of electrons are equal therefore
neutrons and electrons
the proton number (Z) also corresponds to the number of
electrons
2.1. Elements, Compounds and The nucleon number (mass number) is the total number
Mixtures of protons and neutrons in the nucleus of an atom. It is
denoted with the symbol “A“.
Elements -→ Group of atoms that share the SAME number According to scientific convention, the mass number and
of protons. It cannot be broken down into simpler the atomic number of an element is combined in the
substances by chemical methods symbol itself in the following format -→
Compounds -→ Two or more elements chemically bonded
together
Mixtures -→ Two or more elements not chemically bonded
together
2.2. Atomic Structure
An atom is made up of three subatomic particles: protons,
neutrons and electrons
The atom is mostly space with a positively charged
nucleus consisting of protons and neutrons in the centre
and electrons in the empty space around the nucleus
(held together by the electrostatic force of attraction
between them and the positively charged nucleus) 2.4. Electronic Configurations in the
The characteristics of neutrons, protons and electrons are Periodic Table
as follows -→
Atoms have electrons that orbit around a central nucleus, and
Subatomic particle Relative Mass Relative Charge these orbits are referred to as electron shells.
proton 1 +1
neutron 1 0
WWW.ZNOTES.ORG
UPDATED TO 2023-25 SYLLABUS
CAIE IGCSE
CHEMISTRY
SUMMARIZED NOTES ON THE THEORY SYLLABUS
,CAIE IGCSE CHEMISTRY
Boiling Evaporation
1. States of Matter boiling occurs throughout the evaporation only occurs at the
liquid surface
boiling is a relatively faster
1.1. Solids, liquids and gases evaporation is a slow process
process
States of matter are the different forms in which matter
can exist Condensation
The three states of matter are: Solid, liquid and gases
Condensation is the process in which a gas converts into a
Characteristics of Solids, liquids and gases -→ liquid. It happens at the same temperature as the boiling
SOLIDS LIQUIDS GASES point
take the take the As temperature decreases, the energy of particles will
have a
SHAPE shape of their shape of their decrease, making it move more slowly.
definite shape
container container Condensation and Freezing are both energy given out
moderate to reaction.
DENSITY high low
high
don’t have a Freezing and melting (endothermic
have a fixed have a fixed fixed volume -
VOLUME processes)
volume volume expand to fill
the container
1. Melting is the process in which a solid converts to a
non-fluid in
FLUIDITY fluid in nature fluid in nature liquid. It happens at a set temperature called the
nature
melting point
closely- 2. Freezing is the process in which a liquid coverts to a
closely-
packed solid. It happens at the same temperature as the
packed presence of
INTER- together, melting point
together, large, inter-
PARTICULAR barely any
barely any molecular
SPACES inter-
molecular
inter- spaces 1.3. Cooling and Heating Curves
molecular
spaces (Extended)
particles are
immobile, particles are particles are Cooling curves
PARTICULAR however, they able to move mobile and
MOVEMENT can vibrate past one move 1. On cooling, the particles of a gas move slower and
about their another randomly slower and the gas contracts
fixed positions 2. The particles are now closer together and inter-
particles are molecular bonds start to form between them once the
particles are particles are
PARTICULAR arranged condensation point is reached
arranged arranged
ARRANGEMENT regularly in a 3. The temperature of the substance stops falling; the
irregularly irregularly
lattice energy released by bond formation cancels out the
energy lost due to cooling
4. Once all the gas has turned into liquid, the
1.2. Boiling and Evaporation temperature starts to fall again and the liquid begins
to contract until the freezing point is reached
Boiling and Evaporation are (endothermic processes):
5. At the freezing point, inter-molecular bonds between
Boiling and evaporation are processes which involve the the liquid molecules start to develop to form a solid
conversion of a liquid into a gas. 6. At the freezing point, the temperature remains
Both processes allow molecules to move further apart constant until all of the liquid has solidified since, the
from each other. energy released due to bond formation cancels out
the energy lost due to cooling
Boiling Evaporation
The following curve is obtained if this phenomenon is plotted -
evaporation occurs at any
boiling happens at a set the cooling curve -→
temperature below the boiling
temperature called the boiling
point and above the freezing
point
point (liquid)
WWW.ZNOTES.ORG
,CAIE IGCSE CHEMISTRY
1.4. Effects of Temperature and
Pressure on Gas
Gases are compressible in nature. By changing the pressure
acting on them, their volume may be influenced.
1. An increase in external pressure produces a
contraction (decrease) in volume. The gas is said to be
compressed
2. A fall in external pressure produces an expansion
(increase) in volume. The gas is said to be
decompressed
The volume of gases may also be influenced by temperature.
The temperature of a gas affects its internal pressure and
thereby its volume.
1. When temperature increases, the gas molecules have
increased kinetic energy and hit the walls of their
Heating Curves container more often and with greater force. This
causes an increase in internal pressure and an
1. On heating, the particles of a solid start to vibrate increase in volume.
faster and faster in their mean positions and the solid 2. When temperature decrease, the gas molecules have
begins to expand decreased kinetic energy and hit the walls of their
2. Once the melting point is reached, the inter-molecular container less often and with attenuated force. This
bonds between the particles begin to breakdown causes a decrease in internal pressure and a
3. The temperature of the substance at this point decrease in volume.
remains constant until all the solid has turned into a
liquid because the energy received by the system is In conclusion -→
cancelled out by the energy used to break
intermolecular bonds 1. Temperature and volume of gases are directly
4. Once all the solid has turned to liquid, the temperature proportional
starts to rise again and the liquid begins to expand 2. External pressure and volume of gases are inversely
proportional
until the boiling point is reached
5. At the boiling point, the intermolecular bonds between
the liquid molecules start to break down to form gas 1.5. Diffusion
6. At the boiling point, the temperature of the substance
remains constant until all of the liquid has vaporized Diffusion, the net movement of particles from a region of
since, the energy absorbed by the substance is higher concentration to a region of lower concentration, as a
cancelled by the energy used for breakdown of result of their random movement until equilibrium is reached
intermolecular bonds The rate of diffusion is most rapid in gases > liquids > solids
The following curve is obtained if this phenomenon is
plotted - the heating curve -→ 1.6. Effect of Relative Molecular Mass in
Diffusion (Extended)
The rate at which gases diffuse is different and is
dependent on the mass of the gas molecules.
At the same temperature, molecules that have a lower
mass move, on average, faster than those with a higher
mass.
The HCl and NH3 experiment
The experiment involved placing a cotton wool plug soaked in
hydrochloric acid (HCl) at one end of a glass tube and a
cotton wool plug soaked in ammonia (NH3) at the other end.
WWW.ZNOTES.ORG
, CAIE IGCSE CHEMISTRY
The tube was left undisturbed for a period of time, during Subatomic particle Relative Mass Relative Charge
which the gases diffused towards each other. The rate of electron 1/1840 -1
diffusion was measured by observing the distance travelled
by each gas after a fixed time. It was found that ammonia,
Since electrons and protons have opposing and equal
with a lower molecular mass, diffused faster than
charges, the atom’s overall charge is neutral.
hydrochloric acid, which has a higher molecular mass.
Neutrons have the purpose of holding the nucleus
together. The larger the nucleus gets, more are the
Conclusion: Ammonia has a smaller Mr than hydrochloric
neutrons required to hold the nucleus together
acid so ammonia has a greater rate of diffusion. Therefore,
the white ring of ammonium chloride forms near the
hydrochloric acid.
2.3. Proton Number and Nucleon
Number
2. Atoms, Elements and
The proton number (atomic number) is the number of
Compounds protons in the nucleus of an atom.
It is unique to each element. It is denoted with the letter
Atom: The smallest particle of matter made of protons, “Z”. For an atom which is neutral in nature, the number of
protons and the number of electrons are equal therefore
neutrons and electrons
the proton number (Z) also corresponds to the number of
electrons
2.1. Elements, Compounds and The nucleon number (mass number) is the total number
Mixtures of protons and neutrons in the nucleus of an atom. It is
denoted with the symbol “A“.
Elements -→ Group of atoms that share the SAME number According to scientific convention, the mass number and
of protons. It cannot be broken down into simpler the atomic number of an element is combined in the
substances by chemical methods symbol itself in the following format -→
Compounds -→ Two or more elements chemically bonded
together
Mixtures -→ Two or more elements not chemically bonded
together
2.2. Atomic Structure
An atom is made up of three subatomic particles: protons,
neutrons and electrons
The atom is mostly space with a positively charged
nucleus consisting of protons and neutrons in the centre
and electrons in the empty space around the nucleus
(held together by the electrostatic force of attraction
between them and the positively charged nucleus) 2.4. Electronic Configurations in the
The characteristics of neutrons, protons and electrons are Periodic Table
as follows -→
Atoms have electrons that orbit around a central nucleus, and
Subatomic particle Relative Mass Relative Charge these orbits are referred to as electron shells.
proton 1 +1
neutron 1 0
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