Nuclear Structure
Since Rutherford's scattering experiment, physicists have learned much more about the composition of atomic nuclei. The list of particles that make up nucleus has grown long and continues to increase. In chemistry we can take a simple view of the atom, since only three subatomic particles, the proton, neutron and electron, have an effect on chemical behavior.
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| Particle | Mass (g) | Charge (C) | Charge Relative |
| Electron | 9.1095 x 10-28 | -1.6022 x 10-19 | -1 |
| Proton | 1.67252 x 10-24 | +1.6022 x 10-19 | +1 |
| Neutron | 1.67495 x 10-24 | 0 |
0 |
Dalton's idea that all atoms of a given element have the same mass turns out to be
incorrect. We now know that all atoms of a given element have the same number of protons
in the nucleus but, may have different numbers of neutrons. The atomic number (Z) is
the number of protons in the nucleus of an atom of the element. We describe a nucleus by
its atomic number and its mass number. The mass number (A) is the total number of
protons and neutrons in a nucleus. Isotopes are atoms whose nuclei
have the same atomic number but different mass numbers. Chemical symbols for
isotopes are commonly written in the form