Page 22 - Radiochemistry and nuclear chemistry

CHAPTER 2

Nuclei, Isotopes and Isotope Separation

Contents

2.1. Species of atomic nuclei 11
2.2. Atomic masses and atomic weights 12
2.3. Determination of isotopic masses and abundances 14
2.3.1. The mass spectrometer 14
2.3.2. Applications 17
2.4. Isotopic ratios in nature 18
2.5. Physicochemical differences for isotopes 20
2.6. Isotope effects in chemical equilibrium 2O
2.6.1. The partition function 21
2.6.2. Kinetic energy and temperature 22
2.6.3. The partial partition functions 23
2.6.4. The isotopic ratio 24
2.6.5. Paleotemperatures and other applications 25
2.7. Isotope effects in chemical kinetics 27
2.8. Isotope separation processes 30
2.8.1. Multistage processes 31
2.8.2. Chemical exchange 33
2.8.3. Electrolysis 33
2.8.4. Gaseous diffusion 34
2.8.5. Electromagnetic isotope separation 35
2.8.6. Gas centrifugation 36
2.8.7. Other methods of isotope separation 37
2.9. Exercises 39
2.10. Literature 39

According to accepted nuclear models the nucleus is composed of only protons and
neutrons. For example, the oxygen atom of mass number 16 has a nucleus which consists
of 8 protons and 8 neutrons; since neutrons have no charge but are very similar to protons
in mass, the net nuclear charge is + 8. There are 8 extranuclear electrons in the neutral
atom of oxygen.

2.1. Species of atomic nuclei

The term nucleon is used to designate both protons and neutrons in the nucleus. The mass
number A is the total number of nucleons. Thus

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