Noble Gases

4. Discovered in 1900 by Friedrich E. Dorn.
6. All 8A elements are ________ gases at room temperature.
9. Argon prevents metals from oxidizing during _________.
10. Helium has ____ valence electrons.
13. Noble gases are used in ___________ bulbs, strobe lights, and headlights.
16. The position of a satellite may be maintained by a xenon-ion _________ system.
17. Discovered in 1898 by Sir William Ramsay and Morris Travers.
18. Scientists can produce light by passing an _______ current through a gas in a tube.
20. Helium is ________ from natural gas deposits.

1. Discovered in 1868 by Pierre Janssen.
2. Discovered in 1894 by Lord Rayliegh and Sir William Ramsay.
3. Neon, argon, krypton, and xenon are separated from air using ___________ distillation.
5. Noble gases have 8 ________ electrons' except helium.
7. The most common ____________ number for noble gases is +2.
8. Noble gases rarely form ___________.
11. Each noble gas emits a characteristic ____ in a gas discharge tube.
12. The _____________ bulb is filed with argon instead of air.
14. Helium is used in weather balloons and airships because of its low _________.
15. Noble gases are _________, odorless, and tasteless.
19. Noble gases make up what group?