chapter 21 nuclear chemistry 12 th edition. 21.1 radioactivity review from ch. 2 subatomic particles...

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Chapter 21 Nuclear Chemistry 12 th edition

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Page 1: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Chapter 21Nuclear Chemistry

12th edition

Page 2: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

21.1 Radioactivity Review from Ch. 2

Subatomic particles Atoms are neutral: # protons = # electrons Isotopes – atoms with same number of protons but

different number of neutrons

Particle Position Charge Mass (kg)

electron outside nucleus −1 9.11 x 10-31

nucleonproton inside nucleus +1 1.67 x 10-27

neutron inside nucleus 0 1.67 x 10-27

symbolelementXAMassZAtomic

##

Page 3: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Nuclear Chemistry deals with only the nucleus. radioactivity – spontaneous emission of radiation nuclide – nucleus with specified number of protons

and neutrons radionuclide – radioactive nuclide radioisotopes – atoms containing radioactive nuclei radioactive decay – spontaneous decomposition to

form a different, more stable, nucleus with the production of one or more particles

decay series – multiple decay steps through which radioactive nuclides go to reach a stable state

Page 4: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Decay Series

Page 5: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Common Particles in Radioactive Decay and Nuclear Reactions

Decay products: (See Tables 21.2 and 21.3, p. 879)

alpha (α) particle 42He or 4

2α Common for heavy radionuclide

beta (β) particle 0-1β or 0

-1e High-speed electrons; atomic number increases when a decay product

gamma (g) ray 00g High-energy photons; often accompanies

other decay like electron capture

positron 01β or 0

1e Atomic number decreases when a decay product

Decay reactants:

electron capture 0-1e Addition of electron(s) with production of

g rays

neutron capture 10n Neutron capture causes transmutations

and fission-based chain reactions

Page 6: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Fission of 235U initiated by neutron capture

Page 7: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Chain Fission Reaction

Page 8: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Nuclear Equations – sums of both mass and atomic numbers on both sides of equation are equal

Examples:68

31Ga + 0-1e → _____

21287Fr → 208

85At + ______

263106Sg → ______ + 4

2He

Page 9: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

21.4 Rates of Radioactive Decay Radioactive decay follows 1st order kinetics. All half-lives are equal.

ktN

N t

0

ln N – # of radioactive nucleik – decay constant

Individual half-lives vary tremendously:

214Po 2 x 10-4 s144Nd 5 x 1015 yeark

t693.0

2/1

Page 10: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Half-lives

Page 11: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Practice exercise, p. 890

Page 12: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Practice problem 21.33

Page 13: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Practice problem, 90Sr from 1st atomic explosion

Page 14: Chapter 21 Nuclear Chemistry 12 th edition. 21.1 Radioactivity Review from Ch. 2 Subatomic particles Atoms are neutral: # protons = # electrons Isotopes

Mastering problem 21.41