Nuclear ReactionsNuclear Reactions

Nuclear SymbolsNuclear Symbols

23592U

Element symbolMass number (p+ + no)

Atomic number(number of p+)

Types of Radioactive DecayTypes of Radioactive Decayalpha production (): helium

nucleus

beta production ():

92238

24

90234U He Th

90234

91234

10Th Pa e

24 He

10 e

2+

Alpha Alpha RadiationRadiation

Limited to VERY large nucleii.

Beta Beta RadiatioRadiatio

nnConverts a neutron into a proton.

Types of Radioactive DecayTypes of Radioactive Decaygamma ray production ():

positron production :

electron capture: (inner-orbital electron is captured by the nucleus)

92238

24

90234

002U He Th

1122

10

1022Na e Ne

80201

10

79201

00Hg e Au

10 e

Types of RadiationTypes of Radiation

Deflection of Decay ParticlesDeflection of Decay Particles

Opposite charges_________ each other.Like charges_________ each other.

attractrepel

NuclearNuclearStabilityStability

Decay will occur in such a way as to return a nucleus to the band (line) of stability.

Half-life ConceptHalf-life Concept

Sample Half-LivesSample Half-Lives

A A Decay Decay SeriesSeries

A radioactive nucleus reaches a stable A radioactive nucleus reaches a stable state by a series of stepsstate by a series of steps

Nuclear Fission and FusionNuclear Fission and Fusion•Fusion: Combining two light nuclei to form a heavier, more stable nucleus.

•Fission: Splitting a heavy nucleus into two nuclei with smaller mass numbers.0

192

23556

1423691

013n U Ba Kr n

23

11

24

10He H He e

Energy and MassEnergy and MassNuclear changes occur with small but measurable losses of mass. The lost mass is called the mass defect, and is converted to energy according to Einstein’s equation:

E = mc2

m = mass defectE = change in energy

c = speed of lightBecause c2 is so large, even small amounts of mass are converted to enormous amount of energy.

FissionFission

Fission ProcessesFission Processes

Event

NeutronsCausingFission Result

subcritical < 1 reaction stopscritical = 1 sustained reactionsupercritical > 1 violent explosion

A self-sustaining fission process is A self-sustaining fission process is called a chain reaction.called a chain reaction.

A Fission ReactorA Fission Reactor

FusionFusion