LESSON 1: EXPLAINING HOT AND COLDGrade 7 Science: Heat in the Environment

Ms. Willis

LEARNING GOALS

• I can explain the term “heat” using the Particle Theory of Matter.• I can explain the concept of kinetic energy.• I can define “temperature” in scientific terms.• I can describe thermal energy.

WARMTH AND COLDNESS

• Living things need a certain amount of warmth to survive.• How to humans keep warm?• How do animals keep warm?• Birds?

• Overheating can also be dangerous.• How do humans and animals stay cool?

WARMTH AND COLDNESS

•Keeping our homes at a comfortable temperature while minimizing negative effects on the environment is something that scientists have been studying for years.

EXPLAINING HOT AND COLD

• We use the word “heat” to describe something that produces warmth. But what is heat?• Scientists have tried to understand the causes of warmth

and coldness for a long time.

• Today, scientists explain heat using the Particle Theory of Matter.

PARTICLE THEORY OF MATTER

• Recall the 5 main points of the Particle Theory of Matter:• 1. All matter is made up of tiny particles• 2. Particles of have tiny spaces between them.• 3. Particles are moving all the time.• 4. Particles move faster when heated.• 5. Particles attract each other.

HEAT IS A TRANSFER OF ENERGY

• When a warm object comes in contact with a cold object, the faster-moving particles of the warm object bump into slower moving particles of the cold object.

• As a result, energy is transferred.

• To heat an object means to transfer energy to the particles of that object.

• HEAT: the transfer of energy from warmer things to cooler things.

KINETIC ENERGY

• Kinetic energy: energy that all moving objects possess. A particle has more kinetic energy when moving faster and less kinetic energy when moving slower.

• Particles of matter are always moving. Some particles contain more kinetic energy than other particles.

• Most of the particles in a hot object move faster than most of the particles in a cold object. Therefore we can say that a hot object has higher kinetic energy than a cold particles.

• Temperature: a measure of the average kinetic energy of particles.

THERMAL ENERGY

• Thermal Energy: the kinetic energy of the particles AND the energy of attraction between them

• We can increase the thermal energy of a substance by heating it, and we can decrease the thermal energy by cooling it.

• Changes in thermal energy can also cause the substance to change state.