Nuclear Chemistry

Forms of Energy

• The five main forms of energy are:– Heat– Chemical– Electromagnetic– Nuclear– Mechanical

Nuclear Radiation

Many elements can change through radioactivity.-Radioactive elements have unstable nuclei. -Radioactive elements can decay.

– Emit radiation– Can become a different isotope of the

same element– Can become a different element!

Types of Radiation• Alpha Particle

– Helium nucleus with a + 2 charge– The largest radioactive particle– Don’t penetrate very deep

• Beta Particle– A fast moving electron -1 charge– Can travel through paper, but wood or aluminum

will stop it.• Gamma Particle

– Tiny and too small to measure (like photons)– No charge– Travel through clothes and even walls

www.geology.fau.edu/course_info/fall02/ EVR3019/Nuclear_Waste.ppt

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Alpha decay

Alpha particle has a mass of 4. -- 2 protons and 2 neutrons--Mass goes down by 4--Atomic # goes down by 2

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Beta decay

234Th 234Pa + e-1

90 91

beta particle

Beta particle has a tiny mass. -- A neutron is converted to a proton--Mass stays the same--Atomic # goes up by 1

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Gamma radiation

No change in atomic or mass number

11B 11B + 0 5 5 0

boron atom in a high-energy state

Chemical Reactions Nuclear Reactions

Occur when bonds are broken or formed

Occur when nuclei combine, split, & emit radiation

Involve only valence electrons

Can involve protons, neutrons, & electrons

Associated with small energy changes

Associated with large energy changes

Atoms keeps same identity although they may gain, lose, or share electrons, and form new substances

Atoms of one element are often converted into atoms of another element

Temperature, pressure, concentration, and catalysts affect reaction rates

Temperature, pressure, and catalysts do not normally affect reaction rates

Comparison of Chemical and Nuclear Reactions

Radiation Composition& Symbol

Is shielded or stopped by?

Alpha 2 p+ and 2 n0 paper

Beta Stream of high speed e-

Clothing, wood

Gamma Very high energy electromagnetic radiation

Concrete, lead

Nuclear Fission• A heavy nucleus splits into more stable

nuclei of intermediate mass.

Little Boy and Fat Man

Atomic Bombs• Atomic bombs are an

example of Fission Reactions.

• “Little boy” and “Fat man” were Atomic bombs made from fission reactions with uranium and plutonium respectively.

• A fission chain reaction is started and continues until the bomb destroys itself.

Nuclear Fusion• Low-mass nuclei combine to form a heavier, more

stable nucleus.

Hydrogen Bombs

• Hydrogen bombs are an example of nuclear fusion.

• Two isotopes of hydrogen, 2H and 3H, fuse together and produce a lot of energy in the process.

• H-bombs release significantly more energy than atomic bombs.

The Sun: Nuclear Fusion

Sun

+ +

Fourhydrogen

nuclei(protons)

Two betaparticles

(electrons)

Oneheliumnucleus

He e2 H4 42

01-

11 + Energy

Comparing Fission and Fusion

http://media-1.web.britannica.com/eb-media/03/72203-035-4D92BDBC.jpg

Nuclear Fission Nuclear Fusion

Nuclear Fission Nuclear Fusion

A heavy atom splits into two or more lighter nuclei

Ex: Atomic Bombs & Nuclear reactors

High temp and pressure are used to combine light atoms to make heavier atoms

Ex: Fuels the sun and stars & Hydrogen Bombs

Release huge

amounts of energy

Produce nuclear waste

Nuclear Power Plants

map: Nuclear Energy Institute

Nuclear Power Plants• Uranium-235 undergoes nuclear fission and

releases thermal (heat) energy. • This turns water to steam which spins turbines.• The turbines produce electrical energy.

• Nuclear waste is fuel rods with unreacted uranium and radioactive products of fission.

Did You Know ?

http://www.ambrosevideo.com/resources/documents/89.jpg

http://images4.wikia.nocookie.net/__cb20060611033960/schools/images/0/0b/Chart.JPG

• The time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation to form a different isotope

• Half-time emitted • Uranium 235 710 million yrs alpha, gamma• Plutonium 239 24.000 yrs alpha, gamma

• During operation, nuclear power plants produce radioactive wastes, including some that remain dangerous for tens of thousands of years

Half-Life

www.bio.miami.edu/beck/esc101/Chapter14&15.ppt

Relative Doses from

Radiation Sources

cstl-cst.semo.edu/bornstein/BS105/ Energy%20Use%20-%203.ppt

• Genetic damages: from mutations that alter genes

• Genetic defects can become apparent in the next generation

• Cellular damages: to tissue, such as burns, miscarriages & cancers

Effects of Radiation

www.bio.miami.edu/beck/esc101/Chapter14&15.ppt