By Jon Alter, Parker Balduf, Shannon Hupert, and Julia Lantier NOBLE GASES Group 18 By Jon Alter, Parker Balduf, Shannon Hupert, and Julia Lantier

Name Origin Used to be called inert gases, but other gases not included in this group are inert “Noble gas”- derived from German word “edelgas” (“edili”= noble) Alludes to the phrase “noble metals”= metals resistant to corrosion/oxidation. Thus noble refers to the gases’ low reactivity.

Which elements belong to the group? 2 10 18 Helium Neon Argon Rn 36 54 86 Krypton Xenon Radon

General Characteristics Gases at room temperature Monatomic gases, meaning that they exist as single atoms Colorless Density increases as you move vertically down the group Melting point increases as you move vertically down the group Compared to other groups, very low melting points due to weak interatomic forces Almost entirely unreactive- they are stable due to their full outer electron shell

Helium Discovered in 1895 By Sir William Ramsay and independently by Per Teodor Cleve & Nils Abraham Langlet In London, England and Uppsala, Sweden respectively Named after ‘helios,’ the Greek word for the sun First detected in Sun’s spectral lines

The Properties of Helium Values Density 0.0002 g/cm3 Color Colorless Melting Point Unknown  Boiling Point -269 oC Locations on Earth Atmosphere and underground Abundance in the Universe 2nd most abundant

Helium Uses Cooling medium (e.g. in the Large Hadron Collider) Filling airships and balloons Helium-neon gas lasers (used to scan barcodes) Arc Welding Artificial atmospheres for deep sea divers

Neon Discovered in 1898 By Sir William Ramsay and M.W. Travers In London, England Comes from the Greek word ‘neos,’ which means new Found in an experiment of evaporating solid argon under reduced pressure

The Properties of Neon Properties Values Density 0.0008 g/cm3 Color Colorless Melting Point -249 oC Boiling Point -246 oC Locations on Earth Atmosphere Abundance in the Universe 5th most abundant

Neon Uses Neon signs, but only red ones contain pure Neon Cryogenic refrigerate (as a liquid) High Voltage Indicators Lightning Arresters Television tubes Diving Equipment

Argon Name origin: The name is derived from the Greek, 'argos', meaning idle. Found in 1894 by Lord Rayleigh and William Ramsay Was discovered as a result of trying to explain why the density of nitrogen extracted from air differed from that obtained by the decomposition of ammonia Colorless and odorless gas Melting point: -189° C Boiling point: -186° C Density: 0.002 g/cmᶟ There is no reactivity for argon because it is a noble gas. Obtained from the air as a byproduct of oxygen and nitrogen production

Krypton Name origin: The name is derived from the Greek 'kryptos', meaning hidden. Discovered in 1898 by Sir William Ramsay and M.W. Travers Does not react with anything but fluorine gas Colorless, odorless gas Melting point: -157° C Boiling point: -153° C Density: 0.003 g/cmᶟ One of the rarest gases in the Earth’s atmosphere

Xenon Discovery date- 1898 Discovered by-Sir William Ramsay and M.W. Travers Name origin-The name is derived from the Greek 'xenos' meaning stranger. Characteristics:colorless, odorless, unreactive Uses- Xenon is used in certain specialized light sources (electronic flash bulbs used by photographers, sunbed lamps ,and bactericidal lamps used in food preparation, ruby lasers), ion propulsion systems used in satellites, manufacture of 5-fluorouracil (a drug used to treat cancer) Natural abundance: Xenon is present in the atmosphere at a concentration of 0.086 parts per million by volume. It can also be found in the gases that evolve from certain mineral springs. How it is obtained: extraction from liquid air. Melting point -112° C Boiling point -108° C Density 0.005 g/cm3 Atomic number 54

Radon Discovery date- 1902 Discovered by- F.E. Dorn Name origin-The name is derived from radium, as it was first detected as an emission from radium during radioactive decay. Characteristics-Radon is a colorless and odorless gas. It is chemically inert, but radioactive. Uses- Radon decays into radioactive polonium and alpha particles. This emitted radiation makes radon useful in cancer therapy. How it is obtained- Radon is produced naturally from the decay of the isotope radium-226. There is a detectable amount in the Earth’s atmosphere. Melting point -71o C Boiling point -61.7o C Density 0.009 g/cm3 Atomic number 86