Across
- 3. positive particles in the nucleus.
- 5. all matter is made of this
- 6. the sum of the neutrons and protons in an atom
- 7. his model is known as the plum pudding model
- 8. subatomic particle that has a negative charge
Down
- 1. discovered that alpha particles are positively charged ions
- 2. the weighted average of all the masses of an element’s isotopes
- 4. the number of protons in an atom