Transcript Matter Chapter Eleven: Temperature, Heat and the Phases of Matter • 11.1 Temperature and the Phases of Matter • 11.2 Heat.

Matter
Chapter Eleven: Temperature,
Heat and the Phases of Matter
• 11.1 Temperature and the
Phases of Matter
• 11.2 Heat
Investigation 11A
Temperature and Heat
• How are temperature and heat related?
11.1 Temperature
• There are two common
temperature scales.
• On the Fahrenheit scale,
water freezes at 32
degrees and boils at 212
degrees.
• The Celsius scale divides
the interval between the
freezing and boiling
points of water into 100
degrees.
11.1 Thermometer
• A thermometer is an
instrument that
measure temperature.
• A type of thermometer
you have likely seen
uses colored liquid
alcohol to sense
temperature.
11.1 What temperature really is
• Atoms are in constant
motion, even in a solid
object.
• The back-and-forth
jiggling of atoms is
caused by thermal
energy, which is a
kind of kinetic energy.
11.1 What temperature really is
• Temperature measures the kinetic energy
per atom due to random motion.
• A moving rock has both a velocity and a
temperature.
11.1 Absolute zero
• Absolute zero is -273°C.
• You cannot have a temperature lower than
absolute zero.
• Think of absolute zero as the temperature
at which atoms are “frozen.”
11.1 Converting to Kelvin
• The Kelvin
temperature scale is
useful in science
because it starts at
absolute zero.
• To convert from
Celsius to Kelvin,
you add 273 to the
temperature in
Celsius.
11.1 The phases of matter
• A solid holds its shape and does not flow.
• The molecules in a solid vibrate in place,
but on average, don’t move far from their
places.
11.1 The phases of matter
• A liquid holds its volume, but does not
hold its shape—it flows.
• Liquids flow because the molecules can
move around.
11.1 The phases of matter
• A gas flows like a liquid, but can also expand or
contract to fill a container.
• A gas does not hold its volume.
• The molecules in a gas have enough energy to
completely break away from each other.
11.1 The phases of matter
• Within all matter, there is a constant competition
between temperature and intermolecular forces.
• Intermolecular forces tend to bring molecules
together.
11.1 The phases of matter
• The forces in chemical bonds are stronger than
intermolecular forces.
11.1 Melting and boiling
• The melting point is the temperature at
which a substance changes from a solid
to a liquid.
11.1 Melting and boiling
• The temperature at which a liquid
becomes a gas is called the boiling
point.
11.1 Melting and boiling points of
common substances
• Materials have a
wide range of
melting and
boiling points.
11.1 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.