THE BIG IDEA: THE ATOMIC NUCLEUS IS THE

SOURCE OF A TREMENDOUS AMOUNT

OF ENERGY, WHICH POSES BOTH RISKS AND

BENEFITS.

Chapter 15- Nuclear Energy

15.1 Radioactivity

Atoms are composed of protons, neutrons, and electrons

Radioactive- atoms with unstable nuclei

Radioactive decay in Earth’s interior heats the water that spurts from a geyser or wells up from a natural hot spring

15.2 Alpha, Beta, and Gamma Rays

The atoms of radioactive elements emit 3 distinct types of radiation- alpha, beta, and gamma.

Alpha- helium nucleus. Adds a +2 charge to an element’s atomic number.

Beta- electron. Subtracts a -1 charge to an element’s atomic number.

Gamma- Ultra high energy. No change (0) in charge

15.3 Environmental Radiation

Most radiation that we encounter originates in nature

Common source of radiation is Radon-222. Radon is a heavy gas that accumulates in basements. Amounts depend on the local geology.

About 20% of the radiation we encounter comes from outside of nature.

Radiation Damage to the Body

Cells are able to repair most kinds of damage caused by radiation, if it is not too severe.

-Can cause DNA mutation, which can lead to cancer or be passed down genetically if it affects reproductive cells. Usually the mutations are insignificant.

15.4 Transmutation of Elements

The changing of one element to another is transmutation

The gain or loss of protons causes a

change in atomic number, and therefore a change in what element it is.

When transmutation occurs energy is released

15.5 Half Life

The half-life of a radioactive material is the time needed for half of the radioactive atoms to decay.

Half-lives are constant and are not affected by external conditions.

Isotopic Dating

All living things on Earth contain Carbon-14.

All animals eat either plants or other animals, and therefore all animals, including us, have a little Carbon-14 in them.

Carbon-14 dating measures current radioactivity to investigate the age of things that contain carbon.

15.6 Nuclear Fission

Nuclear fission-the splitting of atomic nuclei.

Involves the balance of 2 forces- a strong nuclear force, and a repulsive electric force.

A chain reaction is a self-sustaining reaction in which the products of one reaction event stimulate further reaction events.

Critical mass-the minimum mass chunk needed for a sustainable chain-reaction

15.7 The Mass-Energy Relationship: E=mc2

In this equation, E= energy contained in any mass when at rest, m stands for mass, and c is the speed of light.

-Helps us understand how energy is released in nuclear reactions.

15.8 Nuclear Fusion

Nuclear fusion- the combining of 2 nuclei.- After combination the mass decreases,

because energy is released when fusion occurs.

Thermonuclear fusion- fusion caused by high temperatures.