Across
- 2. The number of protons in an element (6,6)
- 4. The vertical columns of the periodic table (6)
- 5. The central part of an atom, that contains most of the mass (7)
- 7. The horizontal rows of the periodic table (7)
- 9. Neutral particles with a relative mass of 1 (8)
Down
- 1. Negatively charged particles with a relative mass of 1/2000(9)
- 3. The number of protons and neutrons in an element (6,5)
- 6. A substance made of just one type of atom (7)
- 7. Positively charged particles with a relative mass of 1 (7)
- 8. A charged particle formed when an atom gains or loses electrons (3)