Nuclear Chemistry Chapter 25

Nuclear ChemistryChapter 25

Identify the Types of Emission ParticlesBalancing Nuclear EquationsPredict Nuclear Decay ProductsCalculate the Half-Life of a Given Process

Nuclear Decay• Some isotopes are stable, some are not• Band/Zone of stability allows for

predictions

Types of Nuclear Particles• Alpha Particles

• Beta Particles

• Positron

Types of Particles, cont.• Gamma Rays

• Neutron

• Proton

Types of Nuclear Decay• Positron production

713N 6

13C + 10e

• Electron capture 33

73As + -10e 32

73Ge

Alpha Decay• a- particle production

84210Po 82

206Pb + 24He

Types of Radioactive Decay• b-particle production

89227

Ac -10

e + _______

Electron Capture: 0

1 n 11 p + -1

0 e

Types of Nuclear Decay• g-ray production

Excited nucleus ground state nucleus

Spontaneous Fission• When ____________ nuclei ____________

• 96252Cf lighter nuclides and neutrons

Nuclear Fusion• When ___________ nuclei ___________

Nuclear Chain Reaction: Self-Sustaining Fission =Process

• Subcritical – less than one neutron per event

• Critical – one neutron per event to produce another neutron

• Supercritical – more than one neutron from each event causes more events to occur

Balancing Nuclear Reactions

1. 36 Li + 1

2H 24He + ______

2. 88Sr + 84Kr 116Pd + _____

3. 40Ca + 248Cm 147Sm + _____

4. 40Ca + 238U 70Zn + 4 10n +

_____

Balancing Nuclear Reactions1. The alpha decay of iridium-174

2. The beta decay of platinum-199

3. Positron emission from sulfur-31

4. Krypton-76 undergoes electron

capture

The Equation of a Straight Line• y = mx + b

• ln[N] = -kt + ln[N0]

• ln(N/N0) = -kt

• t1/2 = 0.693/k

• Rate = kN

Example 1Technetium 99 is used to form pictures of internal organs in the body and is often used to assess heart damage. The rate constant for 43

99Tc is known to be 1.16 x 10-1 hours. What is the half life of this nuclide?

Example 2The half-life of molybdenum-99 is 67.0 hours. How much of a 1.000 mg sample of42

99 Mo remains after 335 hours?

Example 3The half life of Iodine-131 is 8 days. How much of a 100 g sample will remain after 32 days?

Applications of Nuclear Chemistry

• Dating… how old is an object?

• Medical… dyes detected because it contrasts to what’s already in your body

• Weapons… Very destructive

• Energy… Nuclear Power Plants

Applications of Nuclear Chemistry• ENERGY!!! And lots of it!• Example: The formation of the oxygen

nucleus8 protons and 8 neutrons*mass defect* when the atom forms, it loses mass

Mass of proton = 1.67262 x 10-27 kgMass of neutron = 1.67493 x 10-27 kgMass of oxygen atom = 2.65535 x 10-26 kgE = mc2 .

Mass Defect• E = Δmc2

• Energy per mol?

• Compare to energy per mole of CH4 = -882 kJ/mole

• 14 million times MORE energy from nuclear reactions than chemical reactions

Nuclear Power Plant:Generating Electrical Power