Across
- 2. the sum of the number of protons/neutrons
- 4. Particles in the nucleus with an electric charge of 1+
- 6. Electrically neutral particles in the nucleus
- 7. The verticals columns in the periodic table
- 8. The smallest particle of an element
- 9. The horizontal rows of elements in the periodic table
Down
- 1. Atoms of the same element that have different numbers of neutrons
- 3. Particles with an electric charge of 1-
- 5. The charged center of an atom