The altoalsimce.orgistry the Oxygen The altoalsimce.orgistry the Ozone Oxygen as an Oxidizing certified dealer
Peroxides Methods of prepare O2 The altoalsimce.orgistry of Sulfur
The impact of differences in the strength of X-X and also X=X Bonds The effect of differences in the Electronegativities the Sulfur and also Oxygen The result of distinctions in the abilities of Sulfur and Oxygen to expand Their Valence covering

The altoalsimce.orgistry ofOxygen

Oxygen is the most abundant facet on this planet. Theearth"s late is 46.6% oxygen by weight, the seas are 86%oxygen by weight, and also the atmosphere is 21% oxygen through volume. Thename oxygen comes from the Greek tribe oxys,"acid," and gennan, "to kind orgenerate." Thus, oxygen literally means "acidformer." This name was presented by Lavoisier, who noticedthat compounds affluent in oxygen, such as SO2 and P4O10,dissolve in water to give acids.

The electron construction of an oxygen atom 2s22p4 suggests that neutral oxygen atom canachieve an octet the valence electrons by sharing 2 pairs ofelectrons to type an O=O dual bond, as displayed in the figurebelow.


According come this Lewis structure, all of the electron in theO2 molecule are paired. The compound have to thereforebe diamagnetic it have to be repelled by amagnetic field. Experimentally, O2 is found to it is in paramagneticit isattracted to a magnetic field. This have the right to be described by assumingthat there space two unpaired electron in the

* antibondingmolecular orbitals the the O2 molecule.

This picture shows the the fluid O2 is so strongly attracted come a magnetic field that it will bridge the gap in between the poles the a horseshoe magnet.

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At temperatures listed below -183oC, O2condenses to type a liquid through a characteristic light blue colorthat results from the absorption of light v a wavelength of630 nm. This absorption is not watched in the gas phase and isrelatively weak also in the liquid due to the fact that it requires that threebodies two O2 molecules and a photon collidesimultaneously, i m sorry is a really rare phenomenon, also in theliquid phase.

The altoalsimce.orgistry ofOzone

The O2 molecule is no the just elemental type ofoxygen. In the presence of lightning or another resource of aspark, O2 molecule dissociate to kind oxygen atoms.

O2(g) " width="17" height="9"> 2 O(g)

These O atoms have the right to react through O2 molecule to formozone, O3,

O2(g) + O(g) " width="17" height="9"> O3(g)

whose Lewis structure is shown in the figurebelow.


Oxygen (O2) and ozone (O3) room examplesof allotropes (from the Greek definition "inanother manner"). Through definition, allotropes are differentforms of one element. Due to the fact that they have different structures,allotropes have various altoalsimce.orgical and also physical nature (seetable below).

Properties of allotropes of Oxygen

Oxygen (O2 ) Ozone (O3 )
Melting suggest -218.75oC -192.5oC
Boiling Point -182.96oC -110.5oC
Density (at 20oC) 1.331 g/L 1.998 g/L
O-O bond order 2 1.5
O-O shortcut length 0.1207 nm 0.1278 nm

Ozone is an turbulent compound through a sharp, pungent odor thatslowly decomposes to oxygen.

3 O3(g) " width="17" height="9"> 3 O2(g)

At low concentrations, ozone can be reasonably pleasant. (Thecharacteristic clean odor connected with summer thunderstorms isdue come the development of tiny amounts that O3.)

Exposure to O3 at greater concentrations leader tocoughing, quick beating of the heart, chest pain, and generalbody pain. In ~ concentrations over 1 ppm, ozone is toxic.

One of the characteristic properties of ozone is that is abilityto absorb radiation in the ultraviolet part of the spectrum (> 300 nm), thereby providing a filter the protects us fromexposure come high-energy ultraviolet radiation emitted by the sun.We deserve to understand the prestige of this filter if we think aboutwhat happens once radiation from the sun is absorbed by our skin.

Electromagnetic radiation in the infrared, visible, andlow-energy parts of the ultraviolet spectrum ( 3 and CF2Cl2,which had been supplied as refrigerants and as propellants in aerosolcans, were beginning to accumulate in the atmosphere. In thestratosphere, at altitudes of 10 come 50 km over the earth"ssurface, chlorofluorocarbons decompose to type Cl atoms andchlorine oxides such as ClO as soon as they absorb sunlight. Cl atomsand ClO molecules have actually an odd number of electrons, as shown inthe number below.


As a result, these substances are unusually reactive. In theatmosphere, they react through ozone or v the oxygen atom thatare needed to form ozone.

Cl + O3 " width="17" height="9"> ClO + O2
ClO + O " width="17" height="9"> Cl + O2

Molina and Rowland postulated that these building material wouldeventually deplete the ozone shield in the stratosphere, withdangerous implications for biological systems that would certainly beexposed to enhanced levels the high-energy ultraviolet radiation.

Oxygen together anOxidizing agent

Fluorine is the only aspect that is much more electronegative thanoxygen. Together a result, oxygen gains electron in essentially all itsaltoalsimce.orgical reactions. Every O2 molecule must gain fourelectrons to fulfill the octets the the two oxygen atoms withoutsharing electrons, as shown in the number below.


Oxygen thus oxidizes steels to kind salts in i beg your pardon theoxygen atoms space formally present as O2- ions. Rustforms, for example, once iron reacts through oxygen in the presenceof water to give a salt the formally contains the Fe3+and O2- ions, with an average of 3 water moleculescoordinated to every Fe3+ ion in this solid.

4 Fe(s) + 3 O2(g) " width="17" height="9"> 2 Fe2O3(s) 3 H2O

Oxygen additionally oxidizes nonmetals, such together carbon, come formcovalent compounds in which the oxygen formally has actually an oxidationnumber the -2.

C(s) + O2(g) " width="17" height="9"> CO2(g)

Oxygen is the perfect instance of one oxidizing agentbecause it rises the oxidation state of almost any substancewith which it reacts. In the course of that is reactions, oxygen isreduced. The substances it reacts through are as such reducingagents.


It takes 4 electrons to mitigate an O2 molecule toa pair the O2- ions. If the reaction stops after the O2molecule has gained only 2 electrons, the O22-ion presented in the figure below is produced.


This ion has actually two much more electrons 보다 a neutral O2molecule, which means that the oxygen atoms should share just asingle pair that bonding electron to attain an octet the valenceelectrons. The O22- ion is called the peroxideion due to the fact that compounds that contain this ion space unusually wealthy inoxygen. They are not simply oxides they room (hy-)peroxides.

The easiest method to prepare a peroxide is come react sodium orbarium steel with oxygen.

2 Na(s) + O2(g) " width="17" height="9"> Na2O2(s)
Ba(s) + O2(g) " width="17" height="9"> BaO2(s)

When this peroxides are enabled to react with a strong acid,hydrogen peroxide (H2O2) is produced.

BaO2(s) + 2 H+(aq) " width="17" height="9"> Ba2+(aq) + H2O2(aq)

The Lewis structure of hydrogen peroxide includes an O-Osingle bond, as shown in the number below.


The VSEPR theory predicts the the geometry around each oxygenatom in H2O2 have to be bent. Yet thistheory can not predict whether the four atoms must lie in thesame aircraft or whether the molecule should be visualized together lyingin 2 intersecting planes. The experimentally determinedstructure the H2O2 is shown in the figurebelow.


The H-O-O bond angle in this molecule is just slightly largerthan the angle between a pair of surrounding 2p atomicorbitals on the oxygen atom, and the angle in between the planesthat form the molecule is slightly larger than the tetrahedralangle.

The oxidation number of the oxygen atom in hydrogen peroxideis -1. H2O2 can as such act as anoxidizing agent and also capture two more electrons to form a pair ofhydroxide ions, in which the oxygen has an oxidation number of-2.

H2O2 + 2 e- " width="17" height="9"> 2 OH-

Or, it can act as a reducing agent and also lose a pair ofelectrons to kind an O2 molecule.

H2O2 " width="17" height="9"> O2 + 2 H+ + 2 e-

Reactions in i m sorry a compound concurrently undergoes bothoxidation and reduction are dubbed disproportionationreactions. The commodities of the disproportionation the H2O2are oxygen and also water.

2 H2O2(aq) " width="17" height="9"> O2(g) + 2 H2O(l)

The disproportionation of H2O2 is anexothermic reaction.

2 H2O2(aq) " width="17" height="9"> O2(g) + 2 H2O(l)
o = -94.6 kJ/mol H2O

This reaction is reasonably slow, however, in the absence of acatalyst, such together dust or a metal surface. The principal supplies ofH2O2 revolve around its oxidizing ability.It is provided in dilute (3%) solutions as a disinfectant. In moreconcentrated options (30%), the is offered as a bleaching agent forhair, fur, leather, or the timber pulp supplied to make paper. In veryconcentrated solutions, H2O2 has actually been usedas rocket fuel since of the ease through which the decomposes togive O2.

Methods ofPreparing O2

Small amounts of O2 gas can be all set in anumber that ways.

1. By decomposing a dilute systems of hydrogen peroxide withdust or a steel surface together the catalyst.

2 H2O2(aq) " width="17" height="9"> O2(g) + 2 H2O(l)

2. By reaction hydrogen peroxide through a solid oxidizingagent, such as the permanganate ion, MnO4-.

5 H2O2(aq) + 2 MnO4-(aq) + 6 H+(aq) " width="17" height="9"> 2 Mn2+(aq) + 5 O2(g) + 8 H2O(l)

3. By pass an electric existing through water.

2 H2O(l) " width="17" height="9"> 2 H2(g) + O2(g)

4. By heater potassium chlorate (KClO3) in thepresence of a catalyst till it decomposes.

2 KClO3(s) " width="17" height="9"> 2 KCl(s) + 3 O2(g)

The altoalsimce.orgistry ofSulfur

Because sulfur is directly below oxygen in the routine table,these facets have comparable electron configurations. As a result,sulfur forms countless compounds that are analogs the oxygen compounds,as displayed in the table below. Examples in this table show how theprefix thio- deserve to be used to indicate compounds in whichsulfur replace instead replace an oxygen atom. The thiocyanate (SCN-)ion, because that instance, is the sulfur-containing analog that the cyanate(OCN-) ion.

Oxygen Compounds and Their Sulfur Analogs

Oxygen Compounds Sulfur Compounds
Na2O (sodium oxide) Na2S (sodium sulfide)
H2O (water) H2S (hydrogen sulfide)
O3 (ozone) SO2 (sulfur dioxide)
CO2 (carbon dioxide) CS2 (carbon disulfide)
OCN- (cyanate) SCN- (thiocyanate)
OC(NH2)2 (urea) SC(NH2)2 (thiourea)

There are 4 principal differences in between the altoalsimce.orgistry ofsulfur and oxygen.

1. O=O twin bonds are lot stronger than S=S double bonds.

2. S-S single bonds are practically twice as solid as O-O singlebonds.

3. Sulfur (EN = 2.58) is much much less electronegativethan oxygen (EN = 3.44).

4. Sulfur can broaden its valence shell to hold much more than eightelectrons, yet oxygen cannot.

These watch minor distinctions have necessary consequencesfor the altoalsimce.orgistry of this elements.

The effect ofDifferences in the stamin of X-X and also X=X Bonds

The radius that a sulfur atom is about 60% bigger than the ofan oxygen atom.


As a result, that is harder for sulfur atom to come closeenough together to kind bonds. S=S double bonds room thereforemuch weaker 보다 O=O double bonds.

Double bonds between sulfur and oxygen or carbon atoms can befound in compound such as SO2 and CS2 (seefigure below). However these twin bonds are lot weaker than theequivalent dual bonds to oxygen atom in O3 or CO2.The link dissociation enthalpy because that a C=S double bond is 477kJ/mol, for example, whereas the shortcut dissociation enthalpy because that aC=O twin bond is 745 kJ/mol.


Elemental oxygen consists of O2 molecule in whicheach atom completes that is octet that valence electrons by sharing twopairs of electrons v a solitary neighboring atom. Due to the fact that sulfurdoes not kind strong S=S twin bonds, elemental sulfur usuallyconsists of cyclic S8 molecule in which every atomcompletes that is octet by forming single bonds to two neighboringatoms, as presented in the figure below.


S8 molecules deserve to pack to type more 보다 onecrystal. The many stable type of sulfur consists of orthorhombiccrystals that S8 molecules, which room often uncovered nearvolcanoes. If this crystals space heated till they melt and also themolten sulfur is then cooled, an allotrope of sulfur consistingof monoclinic crystals of S8 molecule isformed. This monoclinic crystals slowly transform themselvesinto the an ext stable orthorhombic structure over a duration oftime.

The propensity of an aspect to kind bonds to itself is called catenation(from the Latin catena, "chain"). Becausesulfur develops unusually strong S-S solitary bonds, it is better atcatenation than any element except carbon. Together a result, theorthorhombic and also monoclinic develops of sulfur space not the onlyallotropes that the element. Allotropes of sulfur likewise exist thatdiffer in the size of the molecule that type the crystal. Cyclicmolecules the contain 6, 7, 8, 10, and 12 sulfur atoms areknown.

Sulfur melts at 119.25oC to type a yellow liquidthat is less viscous than water. If this fluid is heated to 159oC,it turns right into a dark red liquid that cannot be poured from itscontainer. The viscosity the this dark red liquid is 2000 timesgreater than that the molten sulfur since the cyclic S8molecules open up and also link with each other to form long chains of asmany as 100,000 sulfur atoms.


16 K(s) + S8(s) " width="17" height="9"> 8 K2S(s)

This is no the just product that have the right to be obtained, however. Avariety the polysulfide ions through a charge of -2 can be producedthat differ in the number of sulfur atom in the chain.


The result ofDifferences in the Electronegativities of Sulfur and also Oxygen

Because sulfur is much much less electronegative 보다 oxygen, it ismore likely to kind compounds in i beg your pardon it has actually a positiveoxidation number (see table below).

Common Oxidation Numbers for Sulfur

Oxidation Number Examples
-2 Na2S, H2S
-1 Na2S2, H2S2
0 S8
+1 S2Cl2
+2 S2O32-
+21/2 S4O62-
+3 S2O42-
+4 SF4, SO2, H2SO3, SO32-
+5 S2O62-
+6 SF6, SO3, H2SO4, SO42-

In theory, sulfur can react v oxygen to form either SO2or SO3, who Lewis frameworks are provided in the figurebelow.


In practice, burning of sulfur compounds provides SO2,regardless of whether sulfur or a compound of sulfur is burned.

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S8(s) + 8 O2(g) " width="17" height="9"> 8 SO2(g)
CS2(l) + 3 O2(g) " width="17" height="9"> CO2(g) + 2 SO2(g)
3 FeS2(s) + 8 O2(g) " width="17" height="9"> Fe3O4(s) + 6 SO2(g)

Although the SO2 created in these reactions shouldreact with O2 to type SO3, the price of thisreaction is really slow. The price of the switch of SO2into SO3 have the right to be significantly increased by adding anappropriate catalyst.

2 SO2(g) " width="17" height="9"> 2 SO3(g)

Enormous amounts of SO2 are created by industryeach year and also then converted to SO3, which can be usedto produce sulfuric acid, H2SO4. In theory,sulfuric acid have the right to be do by dissolve SO3 gas inwater.

SO3(g) + H2O(l) " width="17" height="9"> H2SO4(aq)

In practice, this is no convenient. Instead, SO3is soaked up in 98% H2SO4, whereby it reactswith the water to type additional H2SO4molecules. Water is climate added, as needed, to keep theconcentration the this solution between 96% and also 98% H2SO4by weight.

Sulfuric mountain is by much the most important industrialaltoalsimce.orgical. It has even been argued that there is a directrelationship in between the quantity of sulfuric acid a countryconsumes and its conventional of living. More than 50% of thesulfuric acid created each year is offered to do fertilizers. Therest is supplied to make paper, artificial fibers and also textiles,insecticides, detergents, feeding additives, dyes, drugs,antifreeze, paints and also enamels, linoleum, man-made rubber,printing inks, cellophane, photographic film, explosives,automobile batteries, and metals such as magnesium, aluminum,iron, and also steel.

Sulfuric mountain dissociates in water to offer the HSO4-ion, i m sorry is well-known as the hydrogen sulfate, or bisulfate, ion.

A range of salts have the right to be created by instead of the H+ions in sulfuric acid v positively fee ions, such as theNa+ or K+ ions.

Sulfurous mountain doesn"t dissociate in water come as an excellent extentas sulfuric acid, yet it is still possible to change the H+ions in H2SO3 with confident ions to formsalts.

Sulfuric acid and also sulfurous acid space both instances of a classof compounds recognized as oxyacids, since they areliterally acids the contain oxygen. Because they are negativeions (or anions) the contain oxygen, the SO32-and SO42- ion are known as oxyanions.The Lewis structures of several of the oxides the sulfur the formoxyacids or oxyanions are provided in the table below.

One of these oxyanions deserves one-of-a-kind mention. This ion,which is well-known as the thiosulfate ion, is developed by the reactionbetween sulfur and also the sulfite (SO32-) ion.

The effect ofDifferences in the capability of Sulfur and also Oxygen to broaden TheirValence shell

The electron construction of oxygen and also sulfur are usuallywritten together follows.

Although this notation reflects the similarity between theconfigurations the the two elements, that hides an importantdifference that permits sulfur to broaden its valence shell to holdmore than eight electrons.

Oxygen reacts v fluorine to form OF2.

The reaction stop at this allude because oxygen have the right to hold onlyeight electron in its valence shell, as displayed in the figurebelow.


Sulfur reacts with fluorine to type SF4 and SF6,shown in the figure below, since sulfur can expand its valenceshell to host 10 or also 12 electrons.

S8(s) + 16 F2(g) " width="17" height="9"> 8 SF4(g)
S8(s) + 24 F2(g) " width="17" height="9"> 8 SF6(g)