Science

1. newest element
6. we breath it
9. first man made element
10. alloy made with (FE) and (C)
11. a tabular arrangement of the chemical elements
14. strongest element
16. a subatomic particle of about the same mass as a proton but without an electric charge
18. What came after the Bronze Age? The___ age
19. valuable material, the Aztecs were destroyed for it
20. The smallest particle of a chemical element that can exist
21. a negatively charged subatomic particle
22. first name of the man who made the first periodic table
23. very popular gem, very strong too

2. Used in bombs, similar to plutonium
3. rarest element
4. a complex arrangement of negatively charged electrons arranged in defined shells about a positively charged nucleus
5. atomic symbol MG, atomic number 12
7. key ingredient in gunpowder
8. an elementary particle that is identical with the nucleus of the hydrogen atom
12. Used in zeppelins
13. atomic symbol PU, atomic number 94
15. substance that cannot be broken down
17. softest element
18. an atom or molecule with a net electric charge due to the loss or gain of one or more electrons