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Group 14: The Family Elements

ƒ configuration is ns2np2 (n is the number) ƒ The half filled orbital allows this to straddle the line between and non metal ƒ The elements show increasing metallic character as you go down a group ƒ The heavier elements of the group are more likely to keep their s and can have oxidation numbers of +2 or +4 Group 14: The Carbon Family Elements (Carbon)

ƒ Central element to and natural intelligences ƒ Carbon has nonmetallic properties ƒ Forms Covalent bonds with and ionic bonds with ƒ Small radium allows for the wide occurrence of C=C and C=O bonds in compounds ƒ Carbon is the only member of group 14 that commonly forms multiple bonds with itself Group 14: The Carbon Family Elements ()

ƒ Central element to electronic technology and artificial intelligences. ƒ Larger atomic size than C which results in relatively few compounds that have Si=Si and Si=O bonds. ƒ Si compounds can act as Lewis where as C compounds typically cannot. ƒ Si compounds can expand its shell by using its d electrons thereby allowing for the accommodation of lone pair electrons of an Lewis . Group 14: The Carbon Family Elements (Forms of Carbon)

Two most common phases of carbon are and Group 14: The Carbon Family Elements (Forms of Carbon)

Diamond

ƒ sp3 Hybridized carbon (tetrahedral) ƒ Only C-C σ bonds Properties: Rigid Transparent Electrically insolating Good conductor of heat

Uses In: Group 14: The Carbon Family Elements (Forms of Carbon) Graphite ƒ sp2 hybridized carbon in a hexagonal network ƒ Electrons are free to move from one carbon to another through π network formed by the overlap of unhybridized p-orbits on each of the carbon Properties: Black Lustrous Electrically conductive Slippery Uses In: Electrical conductors in industry in electrochemical cells in Group 14: The Carbon Family Elements (Forms of Carbon) and Contains very small of graphite Made: Heating gaseous near 1000ºC in the absence of air Uses In: Reinforcing rubber, , and (Activated ) Contains granules of microcrystalline carbon Made: Heating waste in the absence of air and then processing it to increase the , producing a very high specific surface area. Uses In: Air purifiers, gas masks, aquarium water filters, plants (remove organic compounds from drinking water) Group 14: The Carbon Family Elements (Forms of Carbon)

Fullerenes ƒ Soccer ball shaped carbon ƒ Different numbers of carbon atoms ƒ Scientist are investigating weather they would be able to hold an of another element Group 14: The Carbon Family Elements (Silicon)

ƒ Second most abundant atom in the ’s crust ƒ Occurs widely in rocks as silicates (compounds containing the 2- silicate , SiO3 ) ƒ Pure silicon is obtained by reduction of quartzite (a granular form of ) with high purity carbon in an furnace

⎯⎯→∆ SiO2(s) + (s) Si(s) + 2CO(g) (crude is exposed to Cl2 (g)) SiCl4(l) + 2H2(g) Æ Si(s) + 4HCl(g) (purer form of element) ƒ Further purification is necessary before silicon can be used in the industry Group 14: The Carbon Family Elements ( and )

ƒ Germanium is recovered from the flue dust of industrial plants processing ores (it occurs as an impurity in zinc). ƒ Germanium is mainly used in the semiconductor industry.

ƒ Tin is easily obtained from it ore (cassiterite (SnO2)) by reduction with carbon.

⎯1200⎯→⎯°C SnO2(s) + C(s) Sn(l) + CO2(g) ƒ Tin is expensive and not very strong but it is resistant to corrosion. Its main use is in tin plating and used in alloys such as bronze. Group 14: The Carbon Family Elements (Lead)

ƒ Lead is also easily obtained from it ore (galena (PbS)) and converted to its and then reduce with (form of carbon)

⎯⎯→∆ 2PbS(s) + 3O2(g) 2PbO(s) + 2SO2(g) PbO(s) + C(s) Æ Pb(s) + CO(g)

ƒ Lead is durable and malleable which makes it useful in the construction industry ƒ In addition lead is very dense which makes it ideal as radiation shields from x rays ƒ Lead is also used as electrodes for rechargeable batteries Group 14: The Carbon Family Compounds ( of Carbon)

CO2 () ƒ Formed when organic matter burns in the a plentiful source of air and when animals exhale

ƒ CO2 is always present in air but the burning of fossil is increasing the amount of CO2 in the air which is then in-turn leading to global warming

ƒ CO2 is an anhydride of

CO2(g) + H2O(l) ' H2CO3(aq)

ƒ Carbonated beverages have high partial pressures of CO2 to drive the equilibrium to H2CO3 when the beverage is opened the equilibrium shifts to produce CO2 Group 14: The Carbon Family Compounds (Oxides of Carbon) CO () Properties: ƒ Formed when carbon burns Colorless in the a limited source of air Odorless Flammable ƒ This happens in cigarettes and Almost Insoluble badly tuned automobile engines Toxic Gas ƒ CO is the formula anhydride to formic acid (HCOOH) ƒ CO can be produced in the laboratory by the dehydration of formic acid with hot, concentrated

150°C,H SO HCOOH(l) ⎯ ⎯→ ⎯ ⎯2 ⎯ 4 CO(g) + H2O(l) ƒ CO is a and is used in the production of a number of metals, most notably in blast furnaces Group 14: The Carbon Family Compounds (Oxides of Silicon)

Properties: SiO2 (Silica) Hard Rigid network solid ƒ Occurs naturally in quartz, Insoluble in water ƒ Sand is usually small fragments of quartz. The golden brown color is caused by iron oxide impurities ƒ Silica gets its strength from its covalent bonding network structure.

Red = Silicon Purple = Group 14: The Carbon Family Compounds (Oxides of Silicon)

ƒ Silicates can be viewed as various arrangements of tetrahedral oxoanions (an anion of an acid that contains oxygen) of silicon in which each Si-O bond has considerable covalent character ƒ Differences in the internal structure of these highly regular network lead to a wide array of materials, ranging from to Group 14: The Carbon Family Compounds (Oxides of Silicon)

ZnSiO4 (Zircon) ƒ Used as a substitute for in costume jewelry

Ca2Mg5(Si4O11)2(OH)2 (Tremolite or Asbestos)

ƒ Fibrous material which can withstand extreme heat (once widely used for insulation in buildings) however fibers cab lodge in tissue where fibrous scar tissue forms leading to lung caner Group 14: The Carbon Family Compounds (Oxides of Silicon)

Silicones ƒ Synthetic materials that consist of long -O-Si-O-Si- chains with the remaining silicon bonding positions occupied by organic groups such as the (-CH3) ƒ Silicones are used to waterproof fabric because their oxygen atoms attach to the fabric, leaving the hydrophobic methyl groups like tiny inside out umbrellas sticking out of the fabrics surface Group 14: The Carbon Family Compounds ()

ƒ Carbides: Form when a carbon atom bonds with a less electronegative element (In other words carbon acts as an anion) ƒ Carbon is the only group 14 element that will form an anion ƒ Three types of carbides: saline carbides, covalent carbides, and interstitial carbides Group 14: The Carbon Family Compounds (Saline Carbides)

ƒ Saline Carbides are formed when metals of group 1 and 2, aluminum, and a few other metals form ionic bonds with carbon ƒ The s- metals form saline carbides when their oxides are heated with carbon. 2- 4- ƒ The anions present in saline carbides are either C2 or C ƒ C4- carbides are called methides because they produce and the corresponding hydroxide in water:

Example:

Al4C3(s) + 12H2O(g) Æ 4Al(OH)3 (s) +3CH4(g)

ƒ The methide are very strong Bronstead bases Group 14: The Carbon Family Compounds (Saline Carbides)

2- ƒ The species C2 is the ion and the carbides are commonly called ƒ Acetylide ions are very strong Bronstead bases

ƒ Acetylides react with water to produce ethyne (C2H2) and the corresponding hydroxide

ƒ CaC2 ( ) is the most common saline carbide Group 14: The Carbon Family Compounds (Covalent Carbides)

ƒ When carbon reacts with an atom that is only slightly less electronegative than itself and is about the same size, a covalent carbide is formed. ƒ The most common well know covalent carbide is (SiC) Group 14: The Carbon Family Compounds (Interstitial Carbides)

ƒ Interstitial carbides are the compounds formed by the direct reaction of a d-block metal and carbon at temperature above 2000ºC ƒ In these compounds the C atoms occupy the gaps between the metal atoms pinning the metal atoms together into a rigid structure ƒ The materials are very hard and often have melting points well above 3000ºC Group 14: The Carbon Family Common Reactions

Reaction with

M +2X2 Æ MX4 X2 = any group 17 , M = Ge or Sn; Pb gives PbX2 Reactions with O

M + O2 Æ MO2 Reactions with the ions + 2+ M + 2H Æ M + H2 M = Sn or Pb