Halogens
17
Halogens Group 7A (Group 17)
description
Halogens. Group 7A (Group 17). “halogen”. Halos- salt Gen- “genesis”, to form SALT FORMERS. All halogens…. Have 7 electrons in their valence shell Have an oxidation number of -1 Exist, at room temperature, in all three phases of matter Form diatomic molecules. Diatomic molecules. - PowerPoint PPT Presentation
Transcript of Halogens
Halogens
Group 7A(Group 17)
“halogen”
Halos- saltGen- “genesis”, to formSALT FORMERS
All halogens…
Have 7 electrons in their valence shellHave an oxidation number of -1Exist, at room temperature, in all three
phases of matterForm diatomic molecules
Diatomic molecules
A molecule consisting of two atomsF2, Cl2, Br2, I2, At2
fluorine
Atomic Number 9Gas at room temperatureFToothpaste- NaFPale, yellow gasFluere- “to flow”In presence of H, burnswith reactive force
chlorine
Atomic number 17Poisonous, yellow-green gasClBleachPVCDDTHClCCl4
bromine
Atomic number 35Liquid at room temperatureBrManufacture of photographic filmThick, reddish-brown fumes when
exposed to airBromos- “stench”Chlorinated water with brackish water
iodine
Atomic number 53 Solid at room temperature I Iodes- “violet-colored” Seaweed and brine wells Poison “tincture of iodine”- antiseptic Important dietary supplement I-131 half-life 8.1 days
astatine
Atomic number 85Solid at room temperature20 radioactive isotopesAt-210 (t1/2=8.3 hrs)Astatos- “unstable”1 millionth of 1 gram produced artifically
Noble Gases
Group 8AGroup (18)
Noble gases
Considered completely inert until 1960Oxidation number of 0
helium
Atomic number 2He2nd to Hydrogen in universeFound in natural gas and results from
radioactive decayVery low densityUS stockpilesHe-Ne laser in supermarkets
neon
Atomic number 10NeNeos- “new”5th most common element in
atmosphere (.002%)1898- Sir William Ramsay
argon
Atomic number 18ArColorless and odorless1% of earth’s atmosphereArgos- “lazy and inactive”Commercially obtained by distillation of
liquid airIncandescent light bulbsPotassium-argon dating
krypton
Atomic number 36KrKrF4 (1966)Krytos- “hidden”Trace amounts in airOdorless, colorless, tasteless, harmlessPale purple- airport runway and
approach lights
xenon
Atomic number 54XeDensity 5x airXenos- “the strange one”Forms some compoundsRapidly flashing strobe lights
radon
Atomic number 86Rn20 known radioactive isotopesRadon-222 (t1/2= 3.82 days)Tobacco- radon, uranium, lead: 1,000x
greater than those working in nuclear power plants
