Chemistry notes

1. Year 11 Chemistry
Topic 1: Materials and Their Atoms

2. Subtopic 1.1
PROPERTIES AND USES OF
MATERIALS

3. Covered in this subtopic
The uses of materials
are related to their
properties, including
solubility, thermal
and electrical
conductivities,
melting point, and
boiling point.
Nanomaterials are
substances that
contain particles in
the size range 1–100
nm.
Suggest uses of
materials, including
nanomaterials, given
their properties and
vice versa.
Differences in the
properties of
substances in a
mixture can be used
to separate them.
Identify how the
components of a
mixture can be
separated by methods
including filtration,
distillation, and
evaporation.

4. Properties and Uses of
Materials
Chemistry is the study of matter and all
matter is made up of atoms.
It is the atoms that determine the chemical
and physical properties of a substance.

5. Chemical and Physical
Properties
Chemical Properties
These properties explain how a
substance reacts (usually to do with
the electrons in a substance). These
properties are observed through
reactions, where the composition or
identity of the substance may be
changed
Physical Properties
These explain how a substance looks,
feels, smells etc. They are observed
prior to any chemical reaction. These
properties will change if the
substance is changed chemically.

6. Thermal Conductivity
Heat flows from higher to lower temperatures. The rate at which heat
is transferred depends upon the thermal conductivity of a substance.
The rate of heat transfer is generally related to the number of free
electrons.
As such metals are good
conductors of heat (as
metallic bonding causes
many electrons free
movement)
Non metals are poor
conductors of heat (due to
very few free electrons)

7. Thermal
Conductivit
y
Materials that have
poor conductivity are
called insulators.
These materials are
able to store energy
for long periods.
Examples:
Glass, plastic, rubber,
air, wood

8. Electrical
Conductivi
ty
Electricity is the flow
of charged particles
(both positive and
negative).
Charged particles move
when the material is
connected to a source
of electric potential
difference (ie a
Battery).

9. Electrical
Conductivi
ty
Solutions can also be
conductors of electricity.
Such solutions are called
electrolytes.
Electrolytes consist of
charged particles (ions)
called anions and cations.
Anions are negatively
charged
Cations are positively
charged
(remember: have a + sign in

10. Electrical Conductivity
Some substances are
poor conductors of
electricity. They are
known as electrical
insulators.
In these substances,
charged particles are
not free to move when
connected to an
electric potential
difference.
We will learn more
about why this is the
case when we study
the different types

11. Important chemical terms
Melting Point: the
amount of thermal
energy required for
a substance to move
from the solid to
the liquid state.
The stronger the
intermolecular
forces the higher
the melting point.
Boiling Point: the
amount of thermal
energy required to
move from the

12. Solubility
Solubility is the term use to
describe how well two substances mix
/ dissolve in each other.
If they mix well they are called
soluble
If they don’t mix they are called
insoluble
Generally, solubility refers to how
well as substance dissolves in water

13. Solubility
Solute: the material / substance
that you are adding ( the
smaller amount)
Solvent: the material /
substance you are dissolving the
solute in (in excess)
Example: Dried coffee mixed in
hot water: which is the solvent
and which is the solute ?

14. Nanomaterials
Nanomaterials are particles
that are very small, less
than 100nm (100x10-9m)
across.
This area of study is
referred to as
Nanotechnology.
Nanoparticles have a very
high surface area to volume
ratio, which is advantageous
for many applications.

15. Nanoparticles
If substances have a very high surface area, the
rate at which they react is significantly
increased.
They are extremely useful and have applications
that are wide ranging from medical science to
construction and clothing.

16. New-fangled Materials
Aerogels:
https://www.youtube.com/watch?v=k8OhJKR3AA4
Nanorobots:
https://www.sciencephoto.com/media/589889/view
Gallium spoons:
https://www.sciencephoto.com/media/670443/view
Considering one of the above materials:
1. What advantages do these materials have?
2. What drawbacks do these materials have?
3. What applications could these technologies
have?

17. Questions
• Essentials page 7 and 8

18. Materials Materials can be
categorised as pure
substances and mixtures.
Pure substances consist of
only one type of atom or
molecule or formula unit.
Examples: Copper, Sodium
Chloride
Mixtures consist of two or
more substances that are
not chemically bonded.
Examples: air, salty water

19. Mixtures
Mixtures can be described
as being homogenous or
heterogeneous.
Homogenous mixtures have
a composition that is
uniform, such as salty
water.
Heterogeneous mixtures
have a composition that
is non uniform, such as a

20. Characteristics of A Mixture
• Variable Composition (mixtures can be made up
of a lot of different substances)
• Only physical changes occur to form a mixture
• No specific properties
• Can be separated using various separation
techniques

21. Characteristics of a Pure
substance
• Contains only one type of atom or molecule
• Has a definite composition that does not vary
• Has definite measurable physical properties
• Is homogenous

22. Physical processes to separate
mixtures
There are a number of ways in which mixtures can
be separated. Some of the processes are:
• Filtration
• Evaporation
• Distillation (fractional / normal)

23. Filtration
This is a process used to
separate an insoluble solid
from a solvent.
The filter paper contains small
pores
These enable the filtrate to
pass through but not the solid

24. Evaporation
This process will separate a
soluble solid from a
solvent.
In this process the solvent
is heated, where the solvent
will evaporate once its
boiling point is reached.
The solid will have a much
higher boiling point and
hence will remain.

25. Distillation
This is a process used to separate
two solutions (two or more
liquids).
This mixture is heated until the
boiling point of one solution is
reached. It will turn to a vapour
and be removed from the mixture.
This works well if there is a
large difference in boiling point.
If not fractional distillation is
used.
Simple distillation:
https://www.youtube.com/watch?v=Pd
R-cPSx2CI
Fractional distillation:
https://www.youtube.com/watch?v=KC

26. Distillation

27. Other methods to separate
mixtures
A process known as chromatography is
also used to separate mixtures. This
will be explored in depth in later
topics.

28. Questions
Essentials pages 10  11