Nuclear Chemistry

Bravo – 15,000 kilotons

Learning ObjectivesStudents know the three most common forms of radioactive decay (alpha, beta, and gamma) and know how the nucleus changes in each type of decay.

Students know alpha, beta, and gamma radiation produce different amounts and kinds of damage in matter and have different penetrations.

Students know some naturally occurring isotopes of elements are radioactive, as are isotopes formed in nuclear reactions.

Nuclear Symbols

Element symbol

Mass number (p+ + no)

Atomic number(number of p+)

U23592

Types of Radioactive Decay

alpha production ( , a He): helium nucleus

beta production ( , b e):

gamma ray production (g):

ThHeU 23490

42

23892

234 234 090 91 1Th Pa e

0023490

42

23892 2 ThHeU

NuclearStability

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

Alpha Radiation

Alpha decay is limited to VERY large, nuclei such as those in heavy metals.

Beta Radiatio

n

Beta decay converts a neutron into a proton.

Alpha Particle Emission

Beta Particle Emission

Gamma Ray Emission

Symbol or or

Mass Heavy Light No Mass

How it changes the

nucleus

Decreases the mass number by 4

Decreases the atomic number by 2

Converts a neutron into a proton

Increases atomic number by 1

No change to the nucleus

Penetration Low Medium High

Protection provided by…

Skin Paper, clothing Lead

Danger Low Medium High

242He

242 e01 01 00

Learning ObjectivesStudents know protons and neutrons in the nucleus are held together by nuclear forces that overcome the electromagnetic repulsion between the protons.

Students know the energy release per gram of material is much larger in nuclear fusion or fission reactions than in chemical reactions. The change in mass (calculated by E = mc2) is small but significant in nuclear reactions.

Fission

Fission - Splitting a heavy nucleus into two nuclei with smaller mass numbers.

Deuterium – Tritium Fusion Reaction

Fusion - Combining two light nuclei to form a heavier, more stable nucleus.

Energy and Mass

Nuclear 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:

DE = Dmc2

Dm = mass defect DE = change in energy

c = speed of light

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

A Fission Reactor