"The Nature of Electricity": HTML5 Crossword

Across

2. Center of an atom (7)
4. Substance which has very few free electrons (9)
8. A good example of a conductor (6)
10. Orbit travelled by electrons (5)
13. Ordered motion of electric charge (7)
14. Attraction between oppositely charged bodies (8)
15. Process of depositing copper to copper plates (14)
16. Flow of current from positive to negative (12)
18. Loosely bound' particles in the outermost orbit (2 words) (7,9)
19. Electrical discharge that takes place between clouds (9)
20. A good example of an electrical insulator (6)

Down

1. Carries no charge (7)
3. E.M.F. - 'electrical pressure' (2 words) (13,5)
5. A tiny particle (4)
6. Electricity generated by friction (16)
7. Stationary charged particles are said to be this (6)
9. Hinders current flow (10)
11. The effect when current is passed through a filament (7)
12. The unit of measurement for electricity (7)
17. Another name for potential difference (7)