Nuclear SymbolsNuclear Symbols

23592U

Element symbol

Mass number (p+ + no)

Atomic number (number of p+)

Types of Radioactive DecayTypes of Radioactive Decay

alpha 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

nn

Converts a neutron into a proton.

Types of Radioactive DecayTypes of Radioactive Decay

gamma 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

Type of radiation

emitted & symbol

Nature of the radiation

Nuclear Symbol

Penetrating power, and

what will block it

Effect of release of particles from the

nucleus

Alpha

a helium nucleus of 2 protons and 2 neutrons, mass = 4, charge = +2

Low penetration stopped by a few cm of air or

thin sheet of paper

Reduces the atomic mass number by 4

Reduces the atomic number by 2

Beta

high kinetic energy

electrons, mass =

1/1850 of alpha, charge = -1

Moderate penetration, most stopped by a few mm of metals like

aluminum

Is the result of neutron decay and

will increase the atomic number by 1 but will not change the mass number

Gamma

very high frequency

electromagnetic radiation, mass = 0, charge = 0

Very highly penetrating,

most stopped by a thick layer of

steel or concrete, but even a few

cm of dense lead doesn't stop all of

it!

Is electromagnetic radiation released from an excited

nucleus. The atomic number and mass

number do not change.

Deflection of Decay ParticlesDeflection of Decay Particles

Opposite charges_________ each other.

Like charges_________ each other.

attract

repel

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 defect E = change in energy

c = speed of light

Because c2 is so large, even small amounts of mass are converted to enormous amount of energy.

FissionFission

A Fission ReactorA Fission Reactor

FusionFusion

Chemical Fission Fusion

Sample Reaction C + O2 -> CO2 n + U-235 -> Ba-143 + Kr-91 + 2 n H-2 + H-3 -> He-4 + n

Typical Inputs (to Power Plant) (Fuel)

Bituminous Coal UO2 (3% U-235 + 97% U-238) Deuterium & Lithium

Typical Reaction Temperature (K)

700 K 1000 K 108 K

Energy Released per kg of Fuel (J/kg)

3.3 x 107 J/kg 2.1 x 1012 J/kg 3.4 x 1014 J/kg