Across
- 3. Which is the central core of the atom?
- 4. counter Radiation is detected by an instrument called _____________ _____________.
- 7. Which isotope contains 2 neutrons a)protium b)deuterium c)tritium?
Down
- 1. The first radioactive element is discovered by whom?
- 2. What is the mass atomic number of proton?
- 5. What is the maximum number of electrons that can fit into the second shell of an atom?
- 6. Positively charged particle is ____________.