Energy Transformations

Georgia High School Graduation Test: Science Review

Mrs. Kirby

Introduction

• From the key vocabulary, circle the words that you can already define or use in a sentence.

• Write down two or three things that you think are important for you to know today.

Sample Question

1.Describe the process of radioactive decay in which the unstable nucleus of a radioactive isotope spontaneously decays.

Radioactivity

•the spontaneous process that occurs when an unstable nucleus releases particles and/or energy to form a more stable nucleus

Radioisotopes

• unstable radioactive nucleus• examples:

•carbon-14•deuterium (hydrogen with 1 neutron)

•all elements with atomic numbers above 83

Radioactive Decay

ALPHA DECAY

BETA DECAY GAMMA DECAY

•radioactive decay = the release of subatomic particles by radioactive isotopes

•alpha and beta decay result in transformed atom

•gamma decay results in same atom with release of energy

Sample Question

2.Calculate the amount of radioactive substance that will remain after one half-life.

Half-life

• the time it takes for half of the radioactive particles in a radioactive nucleus to decay

• example:• If an original sample of carbon-14 has

a mass of 10 grams and its half-life is 5700 years, how many grams of carbon-14 would remain after one half-life?• ANSWER: 5 grams

Sample Question

3.What is the effect of an increase in temperature on the motion of atoms?

Temperature

•a measure of the average kinetic energy of molecules

•the higher the temperature, the faster the molecules

Sample Question

4.Compare solids, liquids, and gases in terms of shape, volume, and movement of particles.

Phases of MatterSTATE OF MATTER

SHAPE VOLUMEPARTICLE

DESCRIPTION

SOLIDhas definite

shapehas definite

volume

particles move slowly and cannot be

compressed

LIQUID

has no definite shape (takes the

shape of container)

has definite volume

particles move faster but cannot be

compressed

GAShas no definite

shape

has no definite volume (fills volume of container)

particles move the fastest and

can be compressed

Sample Question

5.What is the effect of temperature change on the phases of matter?

Phase Changes

• to increase the temperature of a substance energy must be absorbed by that substance

• to decrease the temperature of a substance energy must be released by that substance

Phase Changes of Water

Phase Change Diagram of Water

Sample Question

6. Give examples and describe the two forms of energy encountered in a system between any of the following: chemical, heat, light, electrical, and mechanical.

Types of Energy

• potential energy = stored energy due to position or chemical composition

• kinetic energy = energy due to motion

Energy SourcesSOURCE DEFINITION EXAMPLES

chemical energy stored in chemical bonds, food, or fuel

cause of burning gas, energy from food

heat total amount of energy of atoms of matter

boiling water, heat

from burning gas

lightenergy that travels in waves and moves through empty

space

any electromagnetic wave (radio, visible, UV, x-rays, gamma)

electrical energy due to the motion of charges

current electricity

mechanical energy acquired or released by moving objects

falling rock, swinging a baseball bat, sound

Heat Energy

• Heat can be transferred through:• Conduction = when objects touch• Convection = when matter moves• Radiation = in the form of waves (does not

require matter)• Conductors = easily transmit energy

• Example: metals• Insulators = do not easily transmit

energy• Example: gases such as air

Conversion of Energy

• The sum of KE and PE is constant if there is no friction.

• Realistically, some energy is transferred to heat due to the friction between the wheels and the track.

Discussion

• The molecular theory of molecules states that the velocity of molecules correlates to the temperature of the system. How are the actions of a group of people affected by the temperature of a room? How are those actions similar to and different from atoms at the same temperature?

Lesson Summarized

• Write a sentence that explains the system discussed.

• Draw a graphic organizer that shows the relationship of the parts to the whole.

Short Quiz Answers

1. Half-time is the time it takes for half of the radioactive particles in a radioactive nucleus to decay.

2. All isotopes have the same atomic number but different atomic masses.

3. Some isotopes are radioactive due to the different number of neutrons.

4. See the table on sources of energy.5. Ice, water, and steam all have the same

chemical composition (H2O) but each are in a different phase.

More Practice

• From the blue book, complete the following questions:• p.53 (26,27,30)• p.61 (1-4)• p.62-63 (6-8)• p.64 (11-14)• p.68 (21-25)