Nuclear EnergyNuclear Energy

Radioactivity and Half-LifeRadioactivity and Half-LifeFission Fission FusionFusion

RadioactivityRadioactivity

The process in The process in which an which an unstable atomic unstable atomic nucleus emits nucleus emits charged particles charged particles and energy.and energy.

Protons and neutrons determine Protons and neutrons determine nuclear reactionsnuclear reactions

One must understand atomic structure One must understand atomic structure to understand radiationto understand radiation

NUCLEAR REACTIONS PRODUCE RADIATION

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Radioactive decay refers to the spontaneous Radioactive decay refers to the spontaneous emission of radiation from the nucleus of an emission of radiation from the nucleus of an unstable atomic nucleusunstable atomic nucleus

• The The ratio of neutrons to protonsratio of neutrons to protons is largely is largely determinant of the stability of the nucleus determinant of the stability of the nucleus and the tendency for radioactive and the tendency for radioactive decay to occurdecay to occur

RADIOACTIVE DECAY

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Types of Nuclear Types of Nuclear RadiationRadiation Alpha decayAlpha decay Beta decayBeta decay Gamma decayGamma decay

Alpha decayAlpha decay

Emits alpha particles which are Emits alpha particles which are positively charged particlepositively charged particle

Are the least penetrating type of Are the least penetrating type of nuclear radiationnuclear radiation

Can be stopped by a sheet of Can be stopped by a sheet of paperpaper

Beta decayBeta decay

Release of negatively charged Release of negatively charged particleparticle

Are more penetrating than alpha Are more penetrating than alpha particles. particles.

Can be stopped by a thin piece of Can be stopped by a thin piece of metalmetal

Gamma decayGamma decay

Nuclear radiation consisting of a Nuclear radiation consisting of a stream of particles with no charge stream of particles with no charge and very little massand very little mass

A form of high energy A form of high energy electromagnetic radiation (high electromagnetic radiation (high frequency & low wavelength)frequency & low wavelength)

Most penetration powerMost penetration power

Half-lifeHalf-life

Is the time required for half of the Is the time required for half of the radioactive substance to decay (as radioactive substance to decay (as either alpha, beta, and gamma either alpha, beta, and gamma radiation)radiation)

Nuclear decay rates are constant for Nuclear decay rates are constant for specific elementsspecific elements

Practical uses: Radioactive datingPractical uses: Radioactive dating Examples:Examples: The half-life of isotope X is 2.0 years. The half-life of isotope X is 2.0 years.

How many years would it take for a 4.0 How many years would it take for a 4.0 mg sample of X to decay and have mg sample of X to decay and have only 0.50 mg of it remain?only 0.50 mg of it remain?

Nuclear FissionNuclear Fission

Practical ApplicationsPractical Applications

FissionFission

Is the splitting of an atomic nucleus Is the splitting of an atomic nucleus into 2 smaller partsinto 2 smaller parts

Tremendous amounts of energy in Tremendous amounts of energy in the form of gamma rays can be the form of gamma rays can be produced from very small amounts of produced from very small amounts of massmass

Chain reaction-neutrons released Chain reaction-neutrons released during the splitting of an initial during the splitting of an initial nucleus triggers a series of nuclear nucleus triggers a series of nuclear fissions.fissions.

ExamplesExamples

Power Plants run Power Plants run off of the fission off of the fission of Uranium-235of Uranium-235

Nuclear weapons Nuclear weapons are an example are an example of an of an uncontrolled uncontrolled chain reactionchain reaction

Fission of UraniumFission of Uranium

Barium and Krypton represent just one of many potential outcomes

Nuclear Disaster-Nuclear Disaster-Chernobyl Chernobyl

FusionFusion

Is a process in which the nuclei of Is a process in which the nuclei of two atoms combine to form a two atoms combine to form a larger nucleuslarger nucleus

Can release huge amounts of Can release huge amounts of energy in the form of high energy energy in the form of high energy gamma raysgamma rays

Fusion cont.Fusion cont.

Temperatures are so high that Temperatures are so high that matter exists as plasma. The sun matter exists as plasma. The sun is 10,000,000 degrees Celsius is 10,000,000 degrees Celsius

Plasma-a state of matter where Plasma-a state of matter where atoms have been striped of their atoms have been striped of their electrons.electrons.

2 problems are creating high 2 problems are creating high temperatures and containing the temperatures and containing the plasmaplasma

Stars…Stars…