Uploaded by Christopher Powell

States of matter notes

What is Chemistry?
Chemistry is the science concerned with the composition, structure, and properties of matter, as
well as the changes it undergoes during chemical reactions. Chemistry is the branch of science
that seeks to explain the behaviour of matter on a molecular level and is considered to be “The
Central Science” because it connects all the other Natural Sciences.
Matter is anything that has mass and takes up space (volume).Matter is practically everything
and everywhere. Matter can exist in 3 distinct with specific arrangement of their particles.
Fig2 showing the different states and the arrangement of their particles
Matter is thought of as made up of tiny particles which are affected by heat and pressure. i.e.
Temperature and pressure determines the phase.
A Comparison of Solids, Liquids and Gases
Usually high
Difficult to compress
Forces of attraction
between the particles
Kinetic energy possessed
by the particles
Possesses small amounts
of kinetic energy
Movement of the particles
Vibrate in a fixed position
“What you do today can improve all your tomorrows”
Takes shape of container it
is in
Usually lower than solids
Can compressed very
slightly by applying
Weaker than those
between particles in a solid
Possess more kinetic
energy than the particles in
a solid
Move slowly past each
Takes the shape of entire
container it is in
Variable- it expands to fill
the container it is in
Very easy to compress
Very weak
Possess large amounts of
kinetic energy
Move around freely and
Changing of states of matter
Matter can exist is any of three states depending on the temperature. It can change from one state
to another by heating or cooling, as this causes a change in the kinetic energy.
When a solid is heated it usually changes state to a liquid then a gas. This occurs because
the particles gain kinetic energy, move increasingly faster and further apart and the forces
of attraction between them becomes weaker and weaker
When a gas is cooled it usually changes state to a liquid and then a solid. This occurs
because the particles lose kinetic energy, move more slowly, gets closer together and the
force of attraction between them becomes increasingly stronger.
N.B- kinetic energy is the energy associated with movement.
Fig 2. Showing the different changes of states.
Add heat
Removal of heat
Some substances do not pass through the liquid phase and they are called sublimation and
deposition. Some substances that go through sublimation are:
 Naphthalene (moth balls)
 Iodine
 Dry ice
“What you do today can improve all your tomorrows”
Heating and cooling curve
 A heating curve is drawn when the temperature of a solid is measured in intervals as it is
heated and changes state to a liquid then to a gas, the temperature is then plotted against
 A cooling curve is drawn when the temperature of a gas is measured at intervals as it is
cooled and changed state to liquid then solid and the temperature is plotted against time.
 The melting point is the constant temperature which a solid changes state to
a liquid
 The boiling point is the constant temperature at which the liquid changes its
state into a gas
 The freezing point is the constant temperature at which the liquid changes its
state to a solid
Particulate theory
The particulate theory of matter is the theory that explains the existence of different phases of
matter and why they exist. This theory is based on the assumptions:
 All matter is made of particles (atoms and/or molecules)
 The particles are in constant random motion (Brownian motion)
 There are spaces between the particles
 There are forces of attraction and repulsion between the particles
“What you do today can improve all your tomorrows”
Evidence to support the particulate theory of matter
The processes of diffusion and osmosis provide evidence to support the fact that all matter is
made of particles.
Diffusion is the net movement of particles from a region of higher concentration to a region of
lower concentration until the particles are evenly distributed.
Eg. 1
When pieces of cotton wool are soaked in concentrated ammonia solution and concentrated
hydrochloric acid are placed simultaneously at the opposite ends of a glass tube, a white ring of
ammonium chloride forms inside the tube. Ammonia solution gives off ammonia gas and
hydrochloric acid gives off hydrogen chloride gas. The particles of the gases diffuse through the
air inside the tube, collide and react to from ammonium chloride.
Ammonia + Hydrogen Chloride  Ammonium Chloride
NH3(g) + HCl (g) NH4Cl (s)
Eg 2
Placing syrup in a container containing water the syrup diffuses to produce a uniformed solution.
The particles go between the spaces of the water particles until evenly distributed. This occurs
with some crystals (solids). Eg sugar.
“What you do today can improve all your tomorrows”
Osmosis is the movement of water particles through a differentially/selectively permeable
membrane (only allows certain molecules to pass through by diffusion) from an area of high
concentration to one of low concentration.
Example 2
The membrane of living tissues is selectively permeable and the cytoplasm inside the cells contains about
80% water.
When a strip of living tissue (such as paw-paw) is placed in water, water molecules move into the
cells by osmosis. Each cell swells slightly and the strips increase in length and becomes rigid.
When the strip is placed in an concentrated sodium chloride(table salt) solution, water molecules
move out of the cell by osmosis. Each cell shrinks slightly and the strip decreases in length and
becomes softer.
Uses of osmosis
1. To control garden pests
Slugs and snails are garden pests whose skin is differentially permeable and always moist. When
table salt (sodium chloride) is sprinkled on slugs and nails, it dissolves in moisture around their
bodies forming a concentrated solution. Water inside their bdies then move out by osmosis and
into the solution. The slugs and snails
2. To preserve food
Salt and sugar are used to preserve foods such as meats, fish and fruit. They both work the same
They draw water out of the cells of the food by osmosis. This prevents the food from decaying
because there is no water available in the cells for the chemical reactions which cause decay
They draw water out of microorganisms (bacteria and fungi) by osmosis. This prevents the food
from decaying because it inhibits the growth of the micro organisms that cause the decay.
“What you do today can improve all your tomorrows”