Section 10.6- Halogens Flashcards
all _____________ are too reactive to be found naturally in their free state
halogens (chlorine, bromine, iodine)
the most reactive of the nonmetallic elements
halogens
the most reactive of any element
fluorine
a greenish-yellow GAS that is denser than air and has a choking and irritating odor
chlorine
a dark red-brown LIQUID that has a choking and irritating odor
bromine
a dark gray SOLID with a slight metallic lister and little odor; when heated, it passes directly into a gaseous state
iodine
means passing directly into a gaseous state
sublimes
fluorine is usually prepared by
electrolysis of molten salts
chlorine is prepared commercially by
electrolysis of either brine or molten rock salt
are often produced commercially by bubbling Cl2 through seawater or brine
bromine and iodine
may be prepared from sodium iodate ore
elmental iodine
the halides except for ____________ may be prepared from their alkali metal halide salts by heating them with concentrated H2SO4 and MnO2
except fluoride
one well-known use of the element _____________ is the in drinking water and in toothpaste as an anticavity ingredient
fluoride
fluoridation is useful because tooth enamel is composed of an insoluble phosphate known as
hydroxyapatite
harder and much more decay resistant than hydroxyapatite and is less affected by acids in the mouth
fluorapatite
a major use of __________ is the manufacture of refrigerants,
fluorine
special chemicals used in air conditioners, refrigerators, freezers, and heat pumps to remove heat from the substance to be cooled
refrigerants
until the 1990s, the most widely used refrigerants were the _____________, a group of compounds containing carbon, fluoride, and chlorine
Freons
two of the most common Freons
Freon-12= AUTOMOBILE air conditioners and refrigerators
Freon-21= household and commercial air conditioners
Freons and related compounds were banned in the early 1990s by the ___________ after they were accused of harming the earth’s ozone layer
Montreal Protocol
Freon-substitute R- 134a was restricted by the 1997 ______________ on “global warming”
Kyoto Protocol
important use of fluorine is in the manufacture of _____________________, used for chemically inert and nonstick properties in electrical insulators, high-temperature plastics, cookware, nonlubricated valves and bearings, etc.
polytetrafluoroethylene (PTFE)
some of the most interesting fluorine compounds are the ________________, organic compounds having their hydrogen atoms replaced with fluorine atoms
perfluorocarbons
one example of perfluorocarbons is a __________________
perflubron
technique using perflubron to save the lives of very premature infants whose lungs are not yet developed enough to breath air; this technique may also be used to treat victims of smoke inhalation, near drowning, or acute respiratory distress
partial liquid ventilation
can slowly dissolve glass and is often used to frost light bulbs and to etch designs in glass surfaces
hydrogen fluoride
one of the most versatile, common elements in the periodic table
chlorine
household bleach is a 5% solution of sodium hypochlorite in which the active ingredient is the
hypochlorite ion
swimming pools are kept clear by the addition of chemicals that produce
hypochlorous acid
one of the most important and widely use chlorine compounds is
a durable, chemically inert plastic manufactured from petroleum and rock salt
PVC
most _______________ either contain chlorine or are manufactured by using chlorine
85% involve chlorine in some way
medicines
uses of chlorine
- Bleaches and disinfectant
- PVC
- Medicines
- Crop-protection
- Banned and restricted chlorine compounds
banned insecticide which saved millions of lives from malaria until the United States sharply curtailed the worldwide use
DDT
nonflammable banned chlorinated compound that have been used extensively in transformers and capacitors on electric power lines because of their chemical stability, low volatility, and ability to conduct heat and not electricity
PCB
the use of ________ compounds has declined in recent years as a result of several circumstances
bromine
bromide compounds that was an important agricultural fumigant in the mid-1990s until the Montreal Protocol mandated that its used be phased out in industrialized nations
methyl bromide
an important use of bromine was in the synthesis of _________
firefighting chemicals that can interfere with the chemical reactions that cause combustion
halons
uses of bromine
- methyl bromide
- HALONS- stop combustion
- silver bromide- photograph
- hypobromous acid- disinfect water
uses of iodine
- tincture of iodine- antiseptic for wounds
- hormone thyroxine contains iodine
- lack of iodine causes goiters
an alcohol solution of iodine that is used for its antiseptic action on cuts or scrapes
tincture of iodine
