21 -- Part 3: 1 Periodic Trends and Charge Density
In the production of Al, the electrolysis bath needs to be kept at 1000 degC, which is done by means of electric heating.
There are two other factors involved in the large energy consumption.
The mass of Al is 27 g mol-1.
9 g Al is the electric current equivalent to the passage of one mole of electrons.
One mole of electrons can produce 12 g Mg, 20 g Ca, or108 g Ag.
Al is an outstanding energy producer when it is used in a battery because of the same factors that make Al a significant energy consumer.
The ionic character of AlF3 is considerable.
The molecule is composed of two AlX3 units.
The two metal atoms are bridged with two Cl atoms.
If the Al atoms are sp3 hybridized, then bonding in this molecule can be described.
There are two ways in which the Cl atom bonds to the Al atoms.
The bond to one Al atom is a conventional covalent bond because each atom contributes one electron to the bond.
The aluminum halides are also called Lewis acids.
They accept a pair of electrons and form adducts.
Adding an alkyl group to a benzene ring is the most common reaction of this type.
There are units to form Al2Cl6.
The cation attacks the benzene ring, freeing a proton that reacts with 3AlCl.
The cryolite, Na3AlF6, is an important halide of aluminum.
Natural deposits of cryolite can be found almost nowhere else.
The O2 is an ion that is in the middle of holes.
Ruby and Fe2+ and Ti4+ are used as abrasives in Alumina, which is a very hard material.
It is resistant to heat and is used in linings for blue sapphires.
Artificial gemstones are used.
The aluminum oxide is very high in reactivity and made by fusing corundum peratures.
A thin, impervious coating of Al2O3 protects aluminum against reaction with water in the range of 4.5-8.6.
An aluminum object is used for the anode in a bath of H2SO41aq2.
The Al2O31s2 + 6 H+1aq2 + 6 e Al2O3 coating can be obtained.
The oxide can be made to absorb certain substances.
Anodized aluminum is used to make everyday items, such as the drinking cups shown in the photograph in the margin, and is also used in architectural components of buildings, such as bronze or black window frames.
It reacts with bases to form a cup.
The most use of aluminum sulfate in important commercial aluminum compound is in Groups 1, 2, 13, and 14.
The acidic hot concentrated H2SO41aq2 is prepared by the reaction of sizing paper.
Half of the calcium carbonate used in water purification is produced in the United States.
When aluminum sulfate is added, the water's pH is adjusted so that it maintains an alkaline medium.
It removes suspended particles from the water.
The size of paper is an impor tant use.
The sizing agent is deposited in the paper.
In the industrial world, alums are a large class of double salts.
The double salts are Li+ M1I2 and K+, Na+, or NH4
Baking powders and potassium aluminum sulfate are used in dyeing.
The fabric is heated in steam after being dipped into a solution of alum.
In both cases, the cations are sufficiently polarizing.
The hydroxides of aluminum and beryllium can be found in basic solutions.
Both metals form a strong oxide coating in the air.
The C4 Be2C and Al4C3 ion are contained in the metals.
Lewis acids and Friedel-Crafts catalysts can be created by Be and Al form halides.
If KF is present, CONCEPT ASSESSMENT AlF is almost insoluble.
To make something happen.
Tin and lead have metallic properties.
Silicon is classified as a metalloid but is mostly nonmetallic in its chemical behavior.
Semiconductor behavior is also exhibited by Silicon.
Carbon is a nonmetal.
We will talk about carbon, Silicon, tin and lead, but germanium is not mentioned.
The most striking differences between carbon and Silicon are outlined in Table 21.7 in the periodic table.
Carbon-atom chains and rings play a central role in establishing the chemical behavior of carbon.
The focus of organic chemistry and biochemistry is the study of the chains and rings.
A Catenation is the joining of atoms into chains.
The chemistry of carbon is emphasized in this section.
Some of the carbon that is distributed in Earth's crust is rich enough for commercial exploitation.
The majority of industrial graphite is made from carbon-based materials.
The high-carbon content material needs to be heated to a temperature of 3000 degC in an electric furnace.
Even when dry, it has excellent lubricating properties.
The planes of carbon atoms are held together by weak forces and can easily slip past one another.
This property is useful in pencil lead, which is a thin rod made from a mixture of graphite and clay that glides easily on paper.
It is used for its ability to conduct electric current, and not the other way around.
The ability to tolerate high temperatures is what determines the use of Graphite in high-temperature environments.
The Bruce H. Frisch/Science Source weight composites are made with a mixture of graphite fibers and fabric.
These materials are used in a wide range of products.
When carbon-based fibers are fibers.
The more stable form of carbon is diamond.
The metal is usually mixed with the substance.
The liquid metal is converted to diamond when the metal is melted.
Diamonds can be picked out of the metal.
At room temperature and pressure, we might expect diamond to return to its original form.
Fortunately for the jewelry industry and for those who treasure diamonds as gems, many phase changes that require a rearrangement in bond type and crystal structure occur extremely slowly.
That is the case with the diamond-graphite transition.
The point is marked by an arrow.
Natural diamonds are used as gemstones.
Synthetic diamonds are shown in the margin for industrial purposes.
The two key properties are used in the industrial use.
Diamonds are very hard and are used as abrasives.
There is no harder substance.
Diamonds have a high thermal conductivity, so they are used in drill bits for cutting steel and other hard materials.
The lifetime of the bit is increased by the rapid dissipation of heat.
Because of their expected properties of diamond to the metal, diamond films can be deposited directly onto metals.
When a metal is coated with a diamond film, the resulting material has a high thermal conductiv films.
The journal has used such materials in heat sinks for computer chips.
The fullerenes earned that honor in 1991.
Mixed crys talline or amorphous structures are some of the forms of carbon that can be obtained.
A smoky flame can be caused by incomplete combustion of natural gas in a Bunsen burner.
Carbon black is used as a material in rubber tires, as a material in printing ink, and as a transfer material in carbon paper, typewriter ribbons, laser printers, and photocopying machines.
New allotropes of carbon have been isolated.
The allotropes were presented in Chapter 12.
The molecule C60 has a shape similar to a soccer ball and is remarkably stable.
C70, C74, and C82 are other fullerenes.
The production of enes can be done by laser under a helium atmosphere.
soot does not contain fullerenes because nitrogen and oxygen interfere with the process of forming them.
We talked about various forms of carbon in Chapter 12.
In this chapter, we focus on Graphene.
The synthetic diamonds are called graphene.
A sheet of Graphene is rolled into a cylinder.
A spherical ball is formed when the flat sheet to pucker is replaced by pentagonal rings.
Graphene has interesting electronic properties because the electrons in the sheets are moving very quickly.
Graphene is expected to play a role in the development of electronic devices.
It was thought impossible that a sheet of carbon could be made.
In 2004, scientists in the United Kingdom used a technique called micromechanical cleavage to isolated graphene.
The process is similar to drawing with a pencil, with the "lead" of which isgraphite, and looking at the traces left by the pencil.
Another way to get Graphene is to peel away layers of carbon atoms from a Graphene surface using a process called exfoliation.
The methods used to produce the flakes contain up to 10 layers of Graphene.
The single-layer flakes have to be found among the thicker ones.
Coke and charcoal are carbon-based materials.
In blast furnaces, it is used to reduce iron oxide to iron metal.
CO and CO2 are the chief oxides of carbon dioxide.
The amount of CO2 in the air is around 400 parts per million.
It occurs to a lesser extent.
The two oxides are important in many ways.
A fuel-lean mixture is burned in an automobile engine.
A fuel-rich mixture is burned in an automobile engine.
Fossil fuels in automobile engines cause CO to be an air pollutant.
Carbon monoxide binding to the iron atoms in hemoglobin is stronger than oxygen.
Carbon monoxide's toxicity arises because it prevents hemoglobin from binding with oxygen.
The molecule shown here is called a heme group.
Four nitrogen atoms surround an iron atom in the center of the group.
In hemoglobin, an O2 molecule projects above the plane of the iron and nitrogen atoms, but here it has been replaced by a CO molecule.
Air pollution can be caused by incomplete combustion of gasoline and a loss of efficiency.
If CO1g2 is formed as a combustion product, gasoline will evolve less heat.
Carbon dioxide can be obtained directly from the atmosphere, but it is not an important source.
The sources of CO2 are summarized in Table 21.8.
Dry ice is the main form of carbon dioxide used for freezing, preserving, and transporting food.
Carbonated beverages make up 20% of CO2 consumption.
Oil recovery in oil fields is an important use.
The major use is by plants and algae.
Green plants use atmospheric CO2 as a source of carbon-containing compounds.
There are major exchanges between the surface of Earth and the atmosphere.
Determine how much less heat is produced per mol of C burned in reaction than in reaction.
The details of the process have been known for a few decades.
His research on C6H12O6 involved up to 100 sequential steps for the conversion of 6 mol CO2 to 1 mol in 1961.
The assimilation of carbon dioxide in plants is a representation of the overall change.
The overall reaction is very cold.
The required energy comes from the sun.
Plants have a green color called chlorophyll.
The reaction produces atmospheric oxygen.
Animals pass carbon atoms to plants.
When the animals breathe and expel gas, some carbon is returned to the atmosphere as CO2.
As plants and animals die and their remains are broken down, additional CO2 returns to the atmosphere.
Coal, petroleum, and natural gas are converted to carbon in decaying organic matter.
This carbon can't be used for photosynthesis.
The cycle of CO2 through the oceans is not represented in the drawing.
The small floating green organisms convert CO2 to organic compounds.
All the animals in the oceans are supported by Phytoplankton, which are at the bottom of the ocean food chain.
Huge quantities of carbon have been deposited in carbonate rocks.
These come from the shells of dead mollusks.
Human activities are more important in the carbon cycle than they were in the past.
Fossil fuels are burning more carbon dioxide than stored carbon.
A future global warming and an increased level of atmospheric CO2 are possible consequences of this distortion of the carbon cycle.
The natural carbon cycle has become a topic of debate.
The synthesis of NH3 is dependent on the use of the reforming of natural gas.
There are three main uses of carbon monoxide.
One is making other compounds.
CO can be used as a reducing agent.
The reaction can be done by heating coke and Fe2O3 in a blast furnace.
A third use of CO is as a fuel, usually mixed with other com bustible gases.
Section 7 discussed this.
The carbides are ionic.
Carbon disulfide is a highly volatile liquid that acts as a solvent.
It's uses as a solvent are decreasing because it's poisonous.
The manufacture of rayon and cellophane is an important use.
CCl4 has been extensively used as a solvent, dry-cleaning agent, and fire extinguisher, but these uses have been declining because CCl4 is a known carcinogen.
Some groupings of atoms have characteristics of a halogen atom.
HCN is a liquid that can boil at room temperature.
It is a very weak acid.
HCN has uses in the manufacture of plastic.
It is used in organic synthesis, as a fumigant, and as a rocket propellant.
Silicon is the second most abundant element in the Earth's crust.
Silicon is to the living world as carbon is to the mineral world.
When coke is used in an electric arcs furnace to reduce the amount of 1SiO22 in the sand, Silicon Elemental Silicon is produced.
Si + 2 CO1g2 is a very high purity Si for solar cells.
The by-product 2 is the Na2SiF6 required for this process.
The Si atom is surrounded by four O atoms.
The way materials scientists represent silicates and similar materials is the same as this view.
In the manufacture of transistors and other Semiconductor Devices, high-purity Silicon is required.
The only stable oxide of Silicon is SiO2.
It is a network covalent solid.
Figure 21-31(a) shows the structure of a network covalent solid.
The structure is similar to the diamond structure and has some similarities to diamond.
The raw material for the glass and ceramics industries is sibel.
There are a number of ways in which these tetrahedra can be arranged.
The empirical formula is LiAl1SiO322.
There are two corners to only two.
The mineral has a fibrous appearance.
The formula of the mula is empirical.
Each Si atom is joined into three adjacent Si atoms.
Bonding between the sheets is not as strong as it is between the sheets.
This is the most common arrangement in the majority of silicate minerals.
SiO2 is a weakly acidic oxide.
The H atom and one OH group Silicate anions are bases and can be acidified.
Crystalline solid or powder that is not of H2O are eliminated from the sample.
These hydrated silicates are formed by the elimination of water from the neighboring molecule of silicic acid.
We might expect carbon to form oxides with similar properties because they are both in group 14 of the periodic table.
The second- and third-period members of group 2 were contrasted on page 994.
The carbon member of the group is different from the higher period members.
The bridges are made of Si.
There are four rings of nonoxygen atoms in the b-cage.
The arrangements described above have an important consequence.
zeolites have important properties.
When eight b-cages are joined together by sharing example, zeolites have been used as sieves to remove rings.
The structure of the mixture is called a structural unit.
In the past, zeolites have been used to remove water from gases.
The four-membered rings of the zeolite can be separated from the benzene and regenerated by heating.
As an ion exchange material, zeolites is an important application.
The structure of the water is more open than the Ca2+, Mg2+, or Fe2+ concentrations.
The structures can be used to exchange the ion with the Na+ ion.
The cations from water react with CO3 or anions of soaps to form insoluble precipitates.
The formation of boiler scale low zeolite can be obtained by heating the water and building up the zeolite in the pipes or under the vacuum.
The containers are used for boiling water.
When there is high affinity for water, the equation below represents the exchange.
A cation-exchange resin is shown here.
By the time the water reaches the bottom of the column, all the multivalent ion have been removed and only Na+ ion remain as counterions.
The exchange can be represented as 2 NaR + M2+ D MR2 + 2 Na+.
The reaction takes place in the forward direction.
The reverse reaction is favored when the concentration of NaCl(aq) is high.
The formation of insoluble precipitates is prevented by the replacement of Ca2+ ion by Na+ ion.
The zeolites are used in detergents to help remove Ca2+ and Mg2+ ion that may be present in water used for washing clothes.
The removal of these ion helps detergents foam better and prevents the formation of insoluble calcium and magnesium compounds.
Some automobile engines need fuels with low boiling points and some need fuels with branched-chain hydrocarbons.
Short-chain or branched-chain hydrocarbons can be converted using zeolite catalysts.
The role of zeolites in the industry is important.
Glass hydrated silicate polymers are important in the ceramics industry.
The final ceramic product is processed into the gel.
The sol-gel process can produce lightweight ceramic materials.
Applications that take advantage of the ceramic's mechanical and structural properties at high temperatures are included in the general category.
These properties have been explored in the development of ceramic components for gas turbine and automotive engines.
A liquid mixture of sodium and calcium silicates can be created if salt and calcium carbonates are mixed with sand.
The structural units in glass are not in a regular arrangement.
The melting behavior of a glass and a solid is different.
A glass will melt over a wide temperature range, whereas a solid will melt at a specific point.
The methods of making different types of glass are described later in this section.
The direct reaction of Si and CH3Cl is typical.
Silicones are important because they are versatile.
Silicones can be obtained as oils or rubber-like materials.
Silicone oils do not oxidize when heated.
They can be cooled to low temperatures without becoming silicones.
Silicone oils are good at high temperatures.
hydrocarbon oils break down at high temperatures and then solidify at low temperatures.
Silicone rubbers retain their elasticity at low temperatures.
They are useful in caulking around windows.
Silicon reacts with the 1X22 to form SiX4.
At room temperature, SiF4 is a gas, SiCl4 is a liquid, and SiI4 is a solid.
Both SiF4 and SiCl4 can be hydrolyzed with water.
It is possible to make very pure Silicon for transistors used in computer chips, as well as very finely divided Silicon for use as a reinforcing filler in Silicone rubber.