Answer:
1. The total number of protons plus neutrons in an atomic nucleus.
2. Atom with the standard atomic number and chemical properties but different atomic mass and physical properties.
3. A particle one-eighth the mass of protons; charge varies. Symbolized by K, π, or μ.
4. Neutral particle of nearly zero mass, produced by decaying nuclei and symbolized by ν.
5. Nuclear particle of the mass of an electron but with a positive charge, symbolized by.