I.P.S.I.A “ Zanussi” di Pordenone
Le Science in pillole
Appunti di scienze
A cura delle insegnanti
Allida De Candido e Cristiana Ziraldo
Subject Area: Science
Class Level and Course Title: first
Class / Science of Earth
Unit of Study: States of Matter
States of matter
The students are introduced to a unit involving
States of Matter
•to known the three states of matter (solid,
liquid and gas);
•to list the general properties of each state;
•to describe them in terms of shape and
•to list everyday examples of each state;
Forms of matter
Matter is anything that takes up space and has weight
Matter is anything that takes up space and has mass or weight.
Matter exists in three forms or states - solid, liquid and gas.
Solids can be
soft or hard
Can you think of something on the Earth that is hard?
Liquids can be
On the Earth
Gas can be
• Particles in a solid have fixed position.
•They are close together.
•If they are positioned in a regular structure they may
•The forces holding them in position are strong, so solids
have their own shape.
•At 0 K (-273°C) the particles are stationary.
•At temperature above 0 K the particles vibrate but
cannot move from their positions.
•As the temperature increases the vibrations become
Liquids take the shape of the container into which
they are put.
Particles in a liquid are still fairly close together.
The forces between particles are not as strong as
in a solid and allow groups of particles to slide over
each other. This is why liquids can flow.
Particles in a liquid therefore do not have a fixed
Liquids do not have a shape of their own.
They take the shape of the container into which
they are put.
These groups of particles move around slowly.
Because the liquid particles move around slowly the dye
gradually mixed with the water.
•The distances between gas are relatively large.
•Therefore they are almost completely free of forces
and so spread out and fill any container into which they
•They are moving around at high speeds (approx. 500
m/sec at room temperature).
• Gases diffuse (spread out and mix) more quickly than
•The directions in which they move have no pattern: they
are random motions (speed and direction).
•The gas particles inside this container are continually
bouncing off the sides. It is these collisions with the
sides of the container that create the pressure inside
What affects the pressure in a gas
There are several factors that will affects the size of
the pressure in a gas.
If the volume of the container is decreased, the particles
will have less distance to travel between collisions.
There will therefore be more collisions per second, i.e. the
pressure will increase.
If more gas particles If the temperature of a gas
are pushed into the is increased its particles
container there will be will move faster, there will
more frequent be more collisions each
collisions and so the second and there will again
pressure will increase. be an increase in pressure.
To sum up
Attributes of matter
SOLID LIQUID GAS
Definite volume Definite volume, No definite
and no volume
shape definite shape or shape
Changes of states
In the daily lives, there are a variety of
matter in the different states.
To be able to classify and describe the
changes of state
To know haw matter changes and what
causes matter to change
Changes of State of Matter
There are different changes that can take place.
Water, for example, can change from water to ice, which
is called freezing.
Freezing is what happens when a liquid changes to a solid.
Water can change from ice to water, which is called
Melting is what happens when a solid changes to a liquid.
Water can also change from a water to steam,
which is called evaporation.
Evaporation is what happens when a liquid changes
to a gas.
Water can change from steam back to water, which
is called condensation.
Condensation occurs when gas changes into a liquid.
There are some substances which can go from
being a solid, directly to the gas state, which is
Solid carbon dioxide, commonly known as Dry Ice,
bypasses the liquid state altogether when it
changes to a gas.
The last change of state is matter going from a gas,
directly to the solid state, which is called deposition.
Water vapours in the air during winter fall in the form of
Cause of changes
Energy is either lost or gained during a change of state.
* When energy is applied to a solid, the tightly packed
particles of matter begin to move around, flowing over each
other. The result is the movement of liquid. The shape
becomes indefinite. The volume, however, does not change,
because the particles are still part of one another.
* When energy is applied to a liquid, the particles that make
up a liquid, begin to move about so rapidly, that they can no
longer hold themselves together. The result is the movement
of a gas. The shape is indefinite, and the volume becomes
•The reverse happens to gas when energy is taken away.
Water vapour, for example begins to liquefy as it cools.
Remember the cool mornings when fog is dense and close to
the ground? What happens? Dewdrops form. The water
vapours in the air cool to form liquid drops on grass.
* When energy is taken away from liquid, the particles in the
liquid slow down to low movement. The resulting solid, has
definite shape and definite volume.
To sum up
1) When a solid changes into a liquid, it is called ......
2) When a solid changes directly into a gas, it is called......
3) When a gas changes into a liquid, it is called ......
4) Matter in a solid state has . . . . . volume and . . . . . .
a) ____ no definite _____ no definite
b) ____ a definite ______ a definite
c) ____ a definite ______ no definite
5) The states of matter are the following:
solids, liquids, gases, plastics.
6) States are also known as ?
7) Which phase of matter does not take the shape of
the container it is in?
8) Liquids are hard to compress. Gases are easy to compress.
9) When solids reach their melting point they
10) What happens when a gas reaches condensation
a) it becomes a solid
b) it becomes a liquid
11) What is evaporation?
a) When liquids turn into vapour
b) When solids turn into vapour
12) What state / phase can fit into any container of any
size and any shape?
a) a gas
c) liquid and solid
13) Gas and vapour means the same.
14) Which state can hold their own shape?
a) a solid
b) a liquid
c) a gas
15) Which state of matter resists very strongly if you
try to change its shape?
16) When a liquid changes into a solid, it is called ......
17) Solidification is when a gas changes into a solid.
18) Matter in a ...... has a ...... volume and ...... shape.
a) gaseous state ___ no definite ___ no definite
b) liquid state _____ no definite ___ definite
c) solid state _____ no definite ___ no definite
19) When water freezes or when water becomes a vapour
is it still the substance: water?
20) Pick the correct statement:
a)Solids become gases at their melting points
b)Solids become liquids at their melting points