GASES

3. At room temperature, it's a yellow crystal-like solid
4. It is used in excimer lasers
6. Carbon _ _ _ _ _ _ _ is needed for photosynthesis in plants
7. The air around us contains about 0.9_% of argon
9. It has an atomic number of 18
10. Another name for the nitrogen family on the periodic table
11. _ _ _ _ _ _ _ Valley is a place in the USA
12. _ _ _ _ _ gases is another name for Group 18 in the Periodic Table
13. A name for compounds containing only hydrogen and carbon atoms
17. When it's liquefied, it can be used as a refrigerant
18. It's name comes from Greek for "the hidden one"
19. The name of Group 16 on the periodic table
21. Inhaling it would give your voice a higher pitch
22. _ _ _ _ _-222 can lead to cancer when inhaled
23. The name of Group 17 on the periodic table
26. Murderers extracted it from flypapers to kill their victims
28. Turkey's Eti Mine Company has opened a factory to specifically produce this for others to eat

1. Tyrian purple dye, produced by the purple dye murex snail, contains it
2. Living things need this to respire
5. Also known as ozone
8. In its liquified form, it is brown until it turns blue when it touches starch
10. The glow of the white solid version of it lead to the word "phosphorescence" being created
14. The most electronegative element
15. The number of gases (including noble gases) in the periodic table
16. Carbon _ _ _ _ _ _ _ _ is produced by cars and is one of the major gases contributing to global warming
19. Used to disinfect swimming pools
20. It takes up about 78% of the air around us
24. Dale R. Corson, Kenneth Ross MacKenzie and Emilio Segre first produced it in 1940
25. Nitrous _ _ _ _ _ is commonly known as laughing gas
27. It's used to make a type of tracing paper