All substances are made of matter. Everything in the universe is either matter or energy
Definition of matter- Anything that takes up space and has mass.
Particle Theory of Matter
- All matter is made of tiny particles.
- These particles are always moving ( vibrating). ( the faster the particles, the
more energy they have)
- There is space between each particle.
- The particles are attracted to one another.
- The particles in one substance are different from the particles in another substance.
The kinetic energy of a substance is the energy it has due to motion.
- The faster an object- the
more kinetic energy.
-The larger the mass of a
moving object, the more
kinetic energy it has.
Kinetic Energy and Temperature
All matter is composed of particles that are moving. This means these particles have kinetic energy. These particles move faster when they are heated.
Therefore we can define temperature
of a substance as: The average kinetic energy of it's particles.
- The faster the particles move- the higher the kinetic energy- the higher
the temperature. Some examples are: when we rub our hands together, we make the particles in our hands move faster, and our hands warm up. Also when we shoot microwaves at food we make the particles in the food vibrate faster, which makes the food hotter.
States of Matter
All matter takes the form of either solid, liquid, or gas. Water is the only substance on Earth that is present in all three forms at the same time.
Solids have a fixed shape and a volume that does not change.
- The reason for this has to do with the particles.The particles
in a solid are packed closely together. There is a strong attraction between the particles which cause them to stay close together. They vibrate in place but do not move around.
Liquids take the shape of the container but have a volume that does not change. The
particles in a liquid are packed closely together but are less attracted to each other than in
a solid. This means they can slide past each other and move slightly around.
Gas takes the shape of the container and the volume of the container. The particles in
a gas are not close together and have little attraction for each other. The particles
collide with each other and move around.
Thermal Expansion - When an object is heated, it's volume increases ( it gets bigger).
Thermal Contraction - When an object is cooled down, it's volume decreases( it gets smaller).
ball and ring apparatus (demonstration).
Train tracks/bridges have expansion gaps so they don't bend/collapse in the summer.
A balloon gets smaller when placed outside on a cold day.
liquid in a thermometer.
Telephone wires expand and sag in summer.
Question: Why does matter expand when heated and contract when cooled?
Answer: When matter is heated, the particles move more quickly. When they collide with each other,because they are moving faster, they have more force and bounce farther apart. When the particles move farther apart, the objects gets bigger- it expands.
Changes of State
There are three states of matter- solids, liquids, and ?gases. When a substance changes from any of these ?states to another state, it is called a Change Of State.
Change of State Name Example
solid to a liquid melting ice cubes melts
solid to a gas sublimation urinal cake
liquid to a gas evaporation sweating
liquid to a solid freezing water to ice
gas to a solid deposition hail
gas to a liquid condensation rain