Section 11.8- Important Semimetals and Their Compounds Flashcards
the second most abundant element in earth’s crust
silicon
silicon does not occur free but rather as
silicates
the most common form of silicon is in
mineral silicates
semimetal that is not very common, occurring primarily as the sulfide along with other metal sulfide ores
germanium
electrical conductivity intermediate between conductors and insulators
semiconductor properties
silicon and germanium’s ___________________ make them well-suited for use in devices such as transistors and diodes
semiconducting properties
silicon is produced by
heating silica with coke to a very high temperature in an electric furnace
the silicon produced is about 98% pure and is suitable for use as an
alloying element in aluminum alloys and spring steel
one of the most important uses of silicon is in the
manufacture of computer chips and other electronic devices
to be suitable for chipmaking, silicon must be further purified by first reacting it with gaseous hydrogen chloride to form
trichlorosilane
more complex polyanion chains are found in substances like
asbestos
most silicates consist of repeating units of Si)4 tetrahedrons, each sharing one or more oxygen atoms with other tetrahedrons to form
polyanions
3D network or polymers of silicates in which all four oxygen atoms are shared between tetrahedrons are called
silica
the most common crystalline form of silica is
sand or granulated quartz
silicates in which some of the silicon atoms are replaced by aluminum atoms are known as
aluminosilicates
when silica is melted, it does not return to its crystalline structure when it cools; rather, it assumes an amorphous or noncrystalline state known as ______________, which is transparent and solid
glass
glass made of pure silica is called _____________________ and is used in halogen light bulbs
fused silica or fused quartz
heat-resistant glass that does not expand and contract a great deal with temperature changes is known as
used in cookware and laboratory equipment
borosilicate glass
aluminosilicate glass
one of th most controversial kinds of silicates is ________________, a natural polysilicate mineral formed by heat and pressure within the earth’s crust
asbestos
the most commonly used form of asbestos is
chrysotile or white asbestos
chrysotile is a fibrous form of a rock called
serpentine
a relatively rare element, with some large deposits found in the US and Asia
boron
one of the most common boron compounds is the mineral
borax
uses of boron
laundry detergents
fire retardants
insecticides
fertilizers
one of the hardest materials known, having almost identical properties to diamonds
boron nitride
