Chapter 6

5. Democritus named this particle
7. Neutral particle in the atom’s nucleus
8. A row on the periodic table
10. (3 words) Shows the numbers and locations of protons, neutrons and electrons in an atom
12. group 1 of the periodic table
13. Very reactive
14. Cannot be broken down into simpler chemical substance by any physical or chemical means
15. Located on the right of the staircase on the periodic table
17. The number of protons and neutrons in an atom’s nucleus
20. An abbreviation for a chemical element

1. Positively charged particle in the atom's nucleus
2. Located along the staircase line
3. Any pure substance that is composed of two or more different elements that are chemically joined
4. The mass of an atom
6. a column with similar properties on the periodic table
9. Group 18 on the periodic table
11. (3 words) These metals are shiny and silvery but not as soft or reactive as alkali metals
16. Located at the top left corner of each element on the periodic table
18. An atom with the same number of protons but a different number of neutrons
19. Part of Thomson's experiment