Atomic Structure

2. The scientist who discovered the electron (7 letters)
4. Number The sum of protons and neutrons in the nucleus of an atom (9 letters)
6. The mass number of an atom is the sum of protons and this (9 letters)
7. Cloud The region where electrons are most likely to be found (9 letters)
8. The atomic model that places electrons in fixed orbits (4 letters)
10. The scientist who developed the electron cloud model (7 letters)
13. Mechanics The concept of electrons moving in orbitals (can be based on probability)(10 letters)
15. A either a protron or neutron (5 letters)
16. A charged atom due to a gain or loss of electrons (7 letters)
19. The number of electrons in a neutral atom equals the number of these (7 letters)
20. The part of an atom that has a positive charge (7 letters)

1. The smallest unit of matter (4 letters)
3. An atom with the same number of protons but a different number of neutrons (7 letters)
5. Number This number defines element and is equal to the number of protons (6 letters)
7. This subatomic particle has a negative charge (8 letters)
9. The center of an atom, containing protons and neutrons (7 letters)
11. The unit used to measure atomic mass (3 letters)
12. Exclusion The principle that states no two electrons in an atom can have the same set of quantum numbers (8 letters)
14. Number The number of protons in the nucleus of an atom (6 letters)
17. A particle found in the nucleus with no charge (7 letters)
18. The specific energy level an electron can occupy (7 letters)