Sates of Matter

2. Properties of Matter
• Chapter Four: Density and Buoyancy
• Chapter Five: States of Matter

3. Chapter Five: States of Matter
• 5.1 Liquids and Gases
• 5.2 Solid Matter

4. Investigation 5A
The Phases of Matter
• How do the mass,
volume, and
densities of solid,
liquid, and gas
compare?

5. 5.1 Liquids and Gases
• A fluid is a form of matter that flows
when any force is applied.
• Gases and liquids are both called fluids.

6. 5.1 Liquids and Gases
• In a liquid, molecules can slide over and
around each other.
• This is why liquids flow and can change
shape.

7. 5.1 Liquids and Gases
• A gas is a phase of matter with high energy
molecules that can expand to fill a container.
• Molecules in a gas are free to move around and
so gases flow just like liquids.
Molecules in a gas have
much more energy than
molecules in a liquid.

8. 5.1 Liquids and Gases
• Gases flow like
liquids, but they also
can expand or
contract to
completely fill any
container.

9. 5.1 Pressure
• Forces in fluids are more complicated than
forces in solids because fluids can change
shape.

10. 5.1 Pressure
• A force applied to a fluid creates
pressure.
• Pressure acts in all directions, not just
the direction of the applied force.

11. 5.1 Pressure
• On the microscopic
level, pressure comes
from collisions between
atoms.
• Every surface can
experience a force from
the constant impact of
trillions of atoms.
• This force is what we
measure as pressure.

12. 5.1 Pressure
• The pressure inside
your tire is what
holds your car up.

13. 5.1 Pressure
• There are two types of forces that act
between atoms.
– The strongest forces are between atoms that
are bonded together into molecules and
compounds.
– A weaker type of force acts between
molecules, or between atoms that are not
bound together.
• We call these weak forces intermolecular
forces.

15. 5.1 Intermolecular Forces
• The phases of matter (solid, liquid, gas) exist
because of competition between thermal energy
and intermolecular forces.
– When molecules have a large amount of thermal
energy (high temperatures), intermolecular forces are
overcome and the molecules spread apart, as in a
gas.

16. 5.1 Intermolecular Forces
– When molecules have a medium amount of
thermal energy, they come together to form a
liquid because the intermolecular forces are
partially overcome.

17. 5.1 Intermolecular Forces
– When molecules have a small amount of
thermal energy, the intermolecular forces are
stronger and molecules become fixed in
place as a solid.

18. 5.1 Melting and boiling
• The melting point is the temperature at
which a substance changes from a solid
to a liquid.

19. 5.1 Melting and boiling
• The temperature at which a liquid
becomes a gas is called the boiling
point.

21. 5.1 Melting and boiling points of
common substances
• Materials have a
wide range of
melting and
boiling points.

22. 5.1 Melting and boiling points of
common substances
• Most materials have a
higher density as a solid
than as a liquid.
• Water is an exception.
• Ice wouldn’t float if ice
were more dense than
water!
• Ice helps fish and other
aquatic organisms to
survive over long, cold
winters because the
protective layer keeps
the water below it
warmer.

23. 5.1 Evaporation and Condensation
• Evaporation occurs
when molecules go from
liquid to gas at
temperatures below the
boiling point.
• Evaporation takes
energy away from a
liquid because the
molecules that escape
are the ones with the
most energy.
Sweat evaporating from
skin removes energy and
cools the body.

24. 5.1 Evaporation and Condensation
• Condensation
occurs when
molecules go from
gas to liquid at
temperatures below
the boiling point.
Dew forms when water
vapor in air condenses into
droplets.

25. 5.1 Convection
• Convection is the transfer of
heat through the motion of
fluids such as air and water.
• Convection occurs because
fluids expand when they heat
up.
– Convection currents occur while
heating water.
– The hot water at the bottom of
the pot rises to the top and
replaces the cold water.

26. 5.1 The atmosphere of Earth
• Air is the most important mixture of gases to
living things on the Earth.
• Air may seem like “nothing” but all the oxygen our
bodies need and all the carbon needed by plants
comes from air.
• Molecular nitrogen (N2) and oxygen (O2) together
account for 97.2 percent of the mass of air.
• Argon and water vapor make up most of the rest.

28. 5.1 The atmosphere of Earth
• As a tree grows, you will
not see soil disappear to
provide mass for the tree.
• The oxygen and hydrogen
atoms in the tree come
from water.
• The carbon atoms come
from the carbon dioxide
(CO2) in the air.

29. 5.1 The atmosphere of Earth
• Earth’s weather is created by gigantic
convection currents in the atmosphere.

30. 5.1 The atmosphere of Earth
• Gravity creates pressure
because fluids have
mass and weight.
• The Earth’s atmosphere
has a pressure due to
the weight of air.
How does pressure change with
altitude in the atmosphere?