3. Copyright © Cengage Learning. All rights reserved
Review
Atomic Number (Z) – number of protons
Mass Number (A) – sum of protons and neutrons
Copyright © Cengage Learning. All rights reserved

4. Some nuclei are unstable; they emit particles spontaneously
Some nuclei are unstable; they emit particles spontaneously. This phenomenon is radioactivity.
All isotopes of the elements with atomic numbers higher than 83 are radioactive.
Mass Number X A Z
Element Symbol
Atomic Number 1p 1 1H or
proton 1n
neutron 0e -1 0b or
electron 0e +1 0b or
positron
4He 2 4a or
a particle A 1 1 4 Z 1 -1 +1 2

34. Nuclear Fission is the process in which a heavy nucleus (mass number >200) divides to form smaller nuclei of intermediate mass and one or more neutrons.
Nuclear Fusion is the combining of small nuclei into large ones

35. Nuclear Fission Nuclear chain reaction Atomic bomb
The TNT was set off first. The explosion forces the section of fissionable material together to form an amount considerably larger than the critical mass.

38. Combining of small nuclei into large ones
Nuclear Fusion
Combining of small nuclei into large ones
Fusion Reaction
Energy Released
2H + 2H H + 1H 1
6.3 x J
2H + 3H He + 1n 1 2
2.8 x J
6Li + 2H He 3 1 2
3.6 x J