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CHAPTER
14
Heat and Thermal Energy
Sources
Key Ideas
• Thermal energy influences temperature, density, pressure, and a
substance’s physical state.
• Thermal energy can be transferred by conduction, convection, and
radiation.
• Most of the thermal energy at Earth’s surface comes from the Sun.
• Earth’s interior has large quantities of thermal energy.
14.1
Temperature and Thermal Energy
• Temperature is an indicator of the average kinetic
energy of particles.
• Kinetic energy is the energy that a substance has due
to its motion.
VOCABULARY
kinetic molecular
theory
kinetic energy
temperature
thermal energy
14.1
Temperature and Thermal Energy
• Temperature is commonly measured in degrees
Celsius or in Kelvin.
VOCABULARY
kinetic molecular
theory
kinetic theory
temperature
thermal energy
• When the temperature of a substance increases, its particles move faster
and spread out. This causes the substance to expand and become less
dense.
14.1
Temperature and Thermal Energy
• Thermal energy includes both kinetic energy and
potential energy from the motion of particles and their
relative positions and forces of attraction.
• thermal energy = (kinetic energy + potential energy) 
number of particles
VOCABULARY
kinetic molecular
theory
kinetic theory
temperature
thermal energy
14.2
Heat
• Heat is defined as the transfer of thermal energy from
one object to another because of differences in their
temperature.
• Thermal energy always moves from warmer to cooler
objects.
VOCABULARY
heat
conduction
radiation
convection
insulators
specific heat capacity
latent heat
14.2
Heat
• Thermal energy can be transferred by conduction,
convection, and radiation.
• Conduction is thermal energy transfer through direct
contact of particles.
• Convection is a method of thermal energy transfer
resulting from the movement of particles in fluids due to
density differences.
• Radiation is the process by which thermal energy is
transferred via electromagnetic waves, without particles
touching.
VOCABULARY
heat
conduction
radiation
convection
insulators
specific heat capacity
latent heat
HEAT RAP:
http://www.youtube
.com/watch?v=7Y3
mfAGVn1c
14.2
Heat
• A substance’s specific heat capacity is a measure of
the amount of energy (measured in joules) needed to
raise the temperature of 1 kg of the substance by 1 °C.
VOCABULARY
heat
conduction
radiation
convection
insulators
specific heat capacity
latent heat
• Latent heat is the energy needed to change a substance from
one state to another without changing temperature.
• Latent heat is absorbed or released during changes of state.
14.2