Sunday, December 23, 2007

Ch.18A Isomerism

Optical Activity

Optical activity describes the phenomenon by which chiral molecules are observed to rotate polarized light in either a clockwise or counterclockwise direction. This rotation is a result of the properties inherent in the interaction between light and the individual molecules through which it passes. Material that is either achiral or equal mixtures of each chiral configuration (called a racemic mixture) do not rotate polarized light, but when a majority of a substance has a certain chiral configuration the plane can be rotated in either direction.

What Is Plane Polarized Light?
Polarized light consists of waves of electromagnetic energy in the visible light spectrum where all of the waves are oscillating in the same direction simultaneously. Put simply, imagine a ray of light as a water wave, with crests and peaks. All the peaks of a water wave point in the same direction (up, against gravity) pretty much at the same time. Light is not usually this way - it's peaks and troughs are often in random array, so one ray of lights peaks might point in a direction 90o opposite of another ray. When all of the rays have their peaks pointing in the same direction - like all the waves in the ocean have peaks pointing up - then those rays of light are said to be polarized to one another.

Why Polarized Light Is Affected
So why do chiral molecules affect only polarized light, and not unpolarized? Well, they do affect unpolarized light, but since the rays have no particular orientation to one another, the effect can not be observed or measured. We observe the polarized light rays being rotated because we knew their orientation before passing through the chiral substance, and so we can measure the degree of change afterwards.

What happens is this; when light passes through matter, e.g. a solution containing either chiral or achiral molecules, the light is actually interacting with each molecule's electron cloud, and these very interactions can result in the rotation of the plane of oscillation for a ray of light. The direction and magnitude of rotation depends on the nature of the electron cloud, so it stands to reason that two identical molecules possessing identical electron clouds will rotate light in the exact same manner. This is why achiral molecules do not exhibit optical activity.

In a chiral solution that is not a racemic mixture, however, the chiral molecules present in greater numbers are configurationally equivalent to each other, and therefore each possesses identical electron clouds to its molecular twins. As such, each interaction between light and one of these 'majority' molecule's electron clouds will result in rotations of identical magnitude and direction. When these billions of billions of interactions are summed together into one cohesive number, they do not cancel one another as racemic and achiral solutions tend to do - rather, the chiral solution as a whole is observed to rotate polarized light in one particular direction due to its molecular properties.

It is just such specificity that accounts for the optical isomerism of enantiomeric compounds. Enantiomers possess identical chemical structures (i.e. their atoms are the same and connected in the same order), but are mirror images of one another. Therefore, their electron clouds are also identical but actually mirror images of one another and not superimposable. For this reason, enantiomeric pairs rotate light by the same magnitude (number of degrees), but they each rotate plane polarized light in opposite directions. If one chiral version has the property of rotating polarized light to the right (clockwise), it only makes sense that the molecule's chiral mirror image would rotate light to the left (counterclockwise).

Equal amounts of each enantiomer results in no rotation. Mixtures of this type are called racemic mixtures, and they behave much as achiral molecules do.

Via a magneto-optic effect, the (-)-form of an optical isomer rotates the plane of polarization of a beam of polarized light that passes through a quantity of the material in solution counterclockwise , the (+)-form clockwise. It is due to this property that it was discovered and from which it derives the name optical activity. The property was first observed by J.-B. Biot in 1815, and gained considerable importance in the sugar industry, analytical chemistry, and pharmaceuticals.

Louis Pasteur deduced in 1848 that the handedness of molecular structure is responsible for optical activity. He sorted the chiral crystals of tartaric acid salts into left-handed and right-handed forms, and discovered that the solutions showed equal and opposite optical activity.

Artificial composite materials displaying the analog of optical activity but in the microwave regime were introduced by J.C. Bose in 1898, and gained considerable attention from the mid-1980s.

Web sites

Saturday, December 22, 2007

Tips to Tame the IIT-JEE

The primary emphasis is to be on depth of knowledge, analytical and comprehension skills and attitude.

If you are a class 11th/12th student, try to synergise your school study with the JEE study. While doing a new topic, always do it first from your school textbook followed by higher level books.

Self Study Plan: School Students: A student going to the school should follow the 4/10 plan, that is self-study for at least 4 hrs. on school days and at least 10 hrs. on holidays. There must be a 7 day or 10 day revision plan as well. 12th Pass Students: A student not going to the school should follow the 10 hrs. plan, that is self-study for at least 10 hrs. everyday. There must be a 7 day or 10 day revision plan as well.

It is more important to do a question completely rather than trying to do more half-done questions.

Note that too much of test taking does not help. Only a deep understanding and other personal attributes can get you through JEE and not blind test taking. The frequency of test taking may be less for JEE 2007 aspirants in class 11th but needs to be higher when they reach class 12th.

Do approximations in calculations keeping an eye on the error.

In objective type of questions, method of elimination of options may work to your advantage in many questions. Using dimensional analysis, putting boundary conditions, putting values of variables, working backwards and many more techniques may work in such scenario.

Monday, December 17, 2007

Another good website

Chemistry lessons Videos

Chemistry E books

Chemistry Lecture notes

Sunday, December 16, 2007

IIT JEE Preparation Online Material

I am putting in effort to put in useful material as number of persons are visiting the blog and visiting number of pages.

I hope they are getting an additional version on the topic apart from their regular institute faculty, coaching instiute faculty, the books they are referring. In my personal study, I realise that reading a variety of books is necessary to clarify certain concepts.

I hope persons who are visiting the blog are getting similar benefit. Some concept is now more clear, as it is explained in a slightly different manner.

I started a blog to develop chemistry glossary

IIT JEE Chemistry Ch.16A. Coordination Compounds

See for a set of questions on this topic the post

Nomenclature of mononuclear coordination compounds, XII 10.1,2,3
Cis-trans and ionisation isomerisms, 10.4
Hybridization and geometries of mononuclear coordination compounds (linear, tetrahedral, square planar and octahedral).10.7

The topics are covered in detail Jauhar's XII book. The section numbers are given beside the topic.

Coordination compounds are a special class of compounds in which the centgral metal atom is surrounded by ions or molecules beyond their valency.

There are also referred to as coordination complexes or complexes.

Haemoglobin, Chlrophyll, and vitamin B-12 are coordinatio compounds of iron, magnesium and cobalt respectively.

The interesting thing of coordination compound is that these are formed from apparently saturated molecules capable of independent existence.

for example, when acqueous ammonia is addedt o green solution of nickel chloride, NiCl2, the colour changes to purple. The ni^2+ ions almost diappear from the solution. The solution on evaporation yields purple crystals corresponding to the formula [Ni(NH-3)-6]Cl-2. such a compound is called coordinatin compound. When this compound is now dissolved in water, there is hardly any evidence of Ni^2+ ions or NH-3 molecules. It ionizes to give a new species [Ni(NH-3)-6]^2+. the species in the square brackets does not ionise further. It remains as a single entity as an ion.

This is the unique feature of coordination compounds.

Nomenclature rules


IUPAC booklet available for download at the above page id.

A coordination entity is composed of a central atom or atoms to which are attached
other atoms or groups of atoms, which are termed ligands. A central atom occupies a
central position within the coordination entity. The ligands attached to a central
atom define a coordination polyhedron. Each ligand is assumed to be at the vertex of
an appropriate polyhedron. The usual polyhedra are shown in Table 3.3 and they are
also listed in Table 4.4. Note that these are adequate to describe most simple
coordination compounds, but that real molecules do not always fall into these simple
categories. In the presentation of a coordination polyhedron graphically, the lines
defining the polyhedron edges are not indicative of bonds.

However, many ligands do not behave as donors of a single electron pair. Some
ligands donate two or more electron pairs to the same central atom from different
donor atoms. Such ligands are said to be chelating ligands, and they form chelate
rings, closed by the central atom. The phenomenon is termed chelation.

The number of electron pairs donated by a single ligand to a specific central atom
is termed the denticity. Ligands that donate one pair are monodentate, those that
donate two are didentate, those that donate three are tridentate, and so on.

Sometimes ligands with two or more potential donor sites bond to two (or more)
different central atoms rather than to one, forming a bridge between central atoms. It
may not be necessary for the ligand in such a system to be like ethane-l ,2-diamine,
with two distinct potential donor atoms. A donor atom with two or more pairs of
non-bonding electrons in its valence shell can also donate them to different centralatoms. Such ligands, of whatever type, are called bridging ligands. They bond to two
or more central atoms simultaneously. The number of central atoms in a single
coordination entity is denoted by the nuclearity: mononuclear, dinuclear, trinuclear,
etc. Atoms that can bridge include 5, 0 and Cl.

The original concepts of metal—ligand bonding were essentially related to the
dative covalent bond; the development of organometallic chemistry has revealed a
further way in which ligands can supply more than one electron pair to a central
atom. This is exemplified by the classical cases of bis(benzene)chromium and
bis(cyclopentadienyl)iron, trivial name ferrocene. These molecules are characterised
by the bonding of a formally unsaturated system (in the organic chemistry sense, but
expanded to include aromatic systems) to a central atom, usually a metal atom.

4.4.3 Mononuclear coordination compounds Formulae. The central atom is listed first. The formally anionic ligands appear next,listed in alphabetical order of the first symbols of their individual formulae. The neutral ligands follow, also in alphabetical order. Polydentate ligands are included in alphabetical order, the formula to be presented as discussed in Chapter 3. The formula for the entire coordination entity, whether charged or not, is enclosed in square brackets. For coordination formulae, the nesting order of enclosing marks is as given on p. 13. The charge on an ion is indicated in the usual way by use of a right superscript. Oxidation states of particular atoms are indicated by an appropriate roman numeral as a right superscript to the symbol of the atom in question, and not in parentheses on the line. In the formula of a salt containing coordination entities, cation always precedes anion, no charges are indicated and there is no space between the formulae for cation and anion.

1. [Co(NH3)6]Cl
2. [PtC14]2

3. [CoC1(NH3)5]C1
6. [Cr"(NCS)4(NH3)2]
4. Na[PtBrC1(N02)(NH3)J
7. [Fe"(CO)4]2
5. [CaC12{OC(NH2)2}2]
The precise form of a formula should be dictated by the needs of the user.

The precise form of a formula should be dictated by the needs of the user. For
example, it is generally recommended that a ligand formula within a coordination
formula be written so that the donor atom comes first, e.g. [TiCl3(NCMe)3], but this
is not mandatory and should not affect the recommended order ofligand citation. It
may also be impossible to put all the donor atoms first, e.g. where two donors are
present in a chelate complex: [Co(NH2CH2CH2NH2)3]3. Whether the ethane-l,2-
diamine is displayed as shown, or simply aggregated as [Co(C2H8N2)3]3t is a matter
of choice. Certainly there is a conflict between this last form and the suggestion that
the donor atoms be written first. The aim should always be clarity, at the expense of
rigid adherence to recommendations.
It is often inconvenient to represent all the ligand formulae in detail. Abbreviations
are often used and are indeed encouraged, with certain provisos. These are: the
abbreviations should all be written in lower case (with minor exceptions, such as Me,
Et and Ph) and preferably not more than four letters; with certain exceptions of wide
currency, abbreviations should be defined in a text when they first appear; in a
formula, the abbreviation should be enclosed in parentheses, and its place in the
citation sequence should be determined by its formula, as discussed above; and
particular attention should be paid to the loss of hydrons from a ligand precursor.
This last proviso is exemplified as follows. Ethylenediaminetetraacetic acid
should be rendered H4edta. The ions derived from it, which are often ligands in
coordination entities, are then (H3edta), (H2edta)2, (Hedta)3 and (edta)4. This
avoids monstrosities such as edta-H2 and edtaH_2 which arise if the parent acid is
represented as edta. A list of recommended abbreviations is presented in Table 4.5. Names. The addition of ligands to a central atom is paralleled in name construction.
The names of the ligands are added to that of the central atom. The ligands are listed
in alphabetical order regardless of ligand type. Numerical prefixes are ignored in this
ordering procedure, unless they are part of the ligand name. Charge number and
oxidation number are used as necessary in the usual way.
Of the two kinds of numerical prefix (see Table 4.2), the simple di-, tn-, tetra-, etc.
are generally recommended. The prefixes bis-, tris-, tetrakis-, etc. are to be used only
with more complex expressions and to avoid ambiguity. They normally require
parentheses around the name they qualify. The nesting order of enclosing marks is as
cited on p. 13. There is normally no elision in instances such as tetraammine and the
two adjacent letters 'a' are pronounced separately.

The names of ligands recommended for general purposes are given in Table 4.6.
The names for anionic ligands end in -o. If the anion name ends in -ite, -ate or -ide, the ligand name is changed to -ito, -ato or -ido. The halogenido names are, by
custom, abbreviated to halo. Note that hydrogen as a ligand is always regarded as
anionic, with the name hydride. The names of neutral and cationic ligands are never
modified. Water and ammonia molecules as ligands take the names aqua and
ammine, respectively. Parentheses are always placed around ligand names, which
themselves contain multiplicative prefixes, and are also used to ensure clarity, but
aqua, ammine, carbonyl (CO) and nitrosyl (NO) do not require them.
The names of all cationic and neutral entities end in the name of the element,
together with the charge (if appropriate) or the oxidation state (if desired). The
names of complex anions require modification, and this is achieved by adding the
termination -ate. All these recommendations are illustrated in the following examples.
1. Dichloro(diphenylphosphine)(thiourea)platinum(ii)
2. K4[Fe(CN)6]
3. [Co(NH3)6]C13
4. [CoCl(NH3)5}Cl2
5. [CoC1(N02)(NH3)4]Cl
6. [PtCl(NH2CH3)(NH3)2]Cl
7. [CuC12{OC(NH2)2}2]
8. K2[PdC14]
9. K[OsCl5N]
10. Na[PtBrC1(N02)(NH3)]
11. [Fe(CNCH3)6]Br2
12. [Ru(HSO3)2(NH3)4]
13. [Co(H20)2(NH3)4]C13
14. [PtC12(C5H5N)(NH3)]
15. Ba[BrF4]2
16. K[CrF4O]
17. [Ni(H20)2(NH3)4]S04
potassium hexacyanoferrate(ii)
potassium hexacyanoferrate(4—)
tetrapotassium hexacyanoferrate
hexaamminecobalt(iii) chloride
pentaamminechlorocobalt(2+) chloride
tetraamminechloronitrito-N-cobalt(iii) chloride
potassium tetrachloropalladate(ii)
potassium pentachloronitridoosmate(2—)
sodium amminebromochloronitrito-
N-platinate( 1—)
hexakis(methyl isocyanide)iron(ii) bromide
tetraamminediaquacobalt(iii) chloride
barium tetrafluorobromate(iii)
potassium tetrafiuorooxochromate(v)
tetraamminediaquanickel(ii) sulfate

***Table to be reformatted


Designation of donor atom. In some cases, it may not be evident which atom in a
ligand is the donor. This is exemplified by the nitrito ligand in Examples 5 and 10,
p. 59. This can conceivably bind through an 0 or N atom. In simple cases, the donor
atom can be indicated by italicised element symbols placed after the specific ligand
name and separated from it by a hyphen, as demonstrated in those particular
examples. More complex examples will be dealt with below. With polydentate
ligands, this device may still be serviceable. Thus, dithiooxalate ion may be attached through S or 0, and formulations such as dithiooxalato-S,S' and dithiooxalato-0,0'should suffice. It could be necessary to use superscripts to the donor atom symbols if these need to be distinguished because there is more than one atom of the same kind to choose from.

Complicated examples are more easily dealt with using the kappa convention,
and this is particularly useful where a donor atom is part of a group that does not
carry a locant according to organic rules. The two oxygen atoms in a carboxylato
group demonstrate this. The designator i is a locant placed after that portion of the
ligand name that denotes the particular function in which the ligating atom is found.
The ligating atoms are represented by superscript numerals, letters or primes affixed
to the donor element symbols, which follow i without a space. A right superscript to
i denotes the number of identically bound ligating atoms.

Inclusion of structural information. The names described so far detail ligands and
central atoms, but give no information on stereochemistry. The coordination number
and shape of the coordination polyhedron may be denoted, if desired, by a
polyhedral symbol. These are listed in Table 4.4. Such a symbol is used as an affix in
parentheses, and immediately precedes the name, separated from it by a hyphen.
This device is not often used.
Geometrical descriptors, such as cis, trans, mer (from meridional) and fac (from
facial), have found wide usage in coordination nomenclature. The meaning is
unequivocal only in simple cases, particularly square planar for the first two and
octahedral for the others

More complex devices have been developed that are capable of dealing with all
cases. The reader is referred to the Nomenclature of Inorganic Chemistry, Chapter
Ionisation Isomers

Ionisation isomers:
Molecular structural formula is same. But different isomers give different ions in solution.

one isomer [PtBr(NH3)3]NO2 -> gives NO2- anions in solution
another isomer [Pt(NH3)3(NO2)]Br -> gives Br- anions in solution

Notice that both anions are necessary to balance the charge of the complex, and that they differ in that one ion is directly attached to the central metal but the other is not.

Geometric Isomers or Cis-Trans isomers

Geometric isomers are two or more coordination compounds which contain the same number and types of atoms, and bonds (i.e., the connectivity between atoms is the same), but which have different spatial arrangements of the atoms.

Not all coordination compounds have geometric isomers.

For example, in the square planar molecule, Pt(NH3)2Cl2, the two ammonia ligands (or the two chloride ligands) can be adjacent to one another or opposite one another.

Note that these two structures contain the same number and kinds of atoms and bonds but are non-superimposable. The isomer in which like ligands are adjacent to one another is called the cis isomer. The isomer in which like ligands are opposite one another is called the trans isomer.

For the common structures which contain two or more different ligands, geometric isomers are possible only with square planar and octahedral structures (i.e., geometric isomers cannot exist for linear and tetrahedral structures).

Note that the two chloride ligands are adjacent to one another in this octahedral complex ion. In aqueous solution, this complex ion has a violet color.

Note that the two chloride ligands are opposite one another in this complex ion. In aqueous solution, this complex ion has a green color.

Material about all isomers - In syllabus only ionic and cis-trans are specially mentioned

Coordination Isomers
Coordination isomers are two or more coordination compounds in which the composition within the coordination sphere (i.e., the metal atom plus the ligands that are bonded to it) is different (i.e., the connectivity between atoms is different).

Not all coordination compounds have coordination isomers.

Coordination isomers have different physical and chemical properties.


Note that the sulfate group is bonded to the Cr atom (via an O atom) and is within the coordination sphere. Note also the octahedral structure. The bromide counterion is needed to maintain charge neutrality with the complex ion (i.e., [Cr(NH3)5(OSO3)]+) and is not shown in the structure.

Note that the bromine atom is bonded to the Cr atom and is within the coordination sphere. Note also the octahedral structure. The sulfate counterion is not shown in the structure.

Linkage Isomers
Linkage isomers are two or more coordination compounds in which the donor atom of at least one of the ligands is different (i.e., the connectivity between atoms is different).

This type of isomerism can only exist when the compound contains a ligand that can bond to the metal atom in two (or more) different ways. Some ligands that can form linkage isomers are shown below.

Not all coordination compounds have linkage isomers.

Linkage isomers have different physical and chemical properties.

Note that the N atom of the nitrite group is bonded to the Co atom. The nitrite group is written as "NO2" in the molecular formula (rather than "ONO") with the N atom nearest to the Co symbol to indicate that the N atom (rather than an O atom) is the donor atom. Note also the octahedral structure.

Note that one of the O atoms of the nitrite group is bonded to the Co atom. The nitrite group is written as "ONO" in the molecular formula (rather than "NO2") with the O atom nearest to the Co symbol to indicate that the O atom is the donor atom. Note also the octahedral structure.

Geometric Isomers
Geometric isomers are two or more coordination compounds which contain the same number and types of atoms, and bonds (i.e., the connectivity between atoms is the same), but which have different spatial arrangements of the atoms.

Not all coordination compounds have geometric isomers.

For example, in the square planar molecule, Pt(NH3)2Cl2, the two ammonia ligands (or the two chloride ligands) can be adjacent to one another or opposite one another.

Note that these two structures contain the same number and kinds of atoms and bonds but are non-superimposable. The isomer in which like ligands are adjacent to one another is called the cis isomer. The isomer in which like ligands are opposite one another is called the trans isomer.

For the common structures which contain two or more different ligands, geometric isomers are possible only with square planar and octahedral structures (i.e., geometric isomers cannot exist for linear and tetrahedral structures).

Note that the two chloride ligands are adjacent to one another in this octahedral complex ion. In aqueous solution, this complex ion has a violet color.

Note that the two chloride ligands are opposite one another in this complex ion. In aqueous solution, this complex ion has a green color.

Optical Isomers
Optical isomers are two compounds which contain the same number and kinds of atoms, and bonds (i.e., the connectivity between atoms is the same), and different spatial arrangements of the atoms, but which have non-superimposable mirror images. Each non-superimposable mirror image structure is called an enantiomer. Molecules or ions that exist as optical isomers are called chiral.

Not all coordination compounds have optical isomers.

The Two Enantiomers of CHBrClF
Note that the molecule on the right is the reflection of the molecule on the left (through the mirror plane indicated by the black vertical line). These two structures are non-superimposable and are, therefore, different compounds.

Pure samples of enantiomers have identical physical properties (e.g., boiling point, density, freezing point). Chiral molecules and ions have different chemical properties only when they are in chiral environments.

Optical isomers get their name because the plane of plane-polarized light that is passed through a sample of a pure enantiomer is rotated. The plane is rotated in the opposite direction but with the same magnitude when plane-polarized light is passed through a pure sample containing the other enantiomer of a pair.

web sites

Thursday, December 13, 2007

Tutorials Organic Chemistry

On Prentice Hall site, there are tutorials for organic Chemistry for Wades book

Sunday, December 9, 2007

Doubts regarding Chemistry Concepts - Refer Index of Doc Brown

For many concepts in chemistry refer this index.

TMH Ch. 34 Exercises in Organic Chemistry

Practical organic chemistry:

JEE Syllabus

Detection of elements (N, S, halogens);
Detection and identification of the following functional groups:
hydroxyl (alcoholic and phenolic),
carbonyl (aldehyde and ketone),
carboxyl, amino and nitro;
Chemical methods of separation of mono-functional organic compounds from binary mixtures.

Detection of Elements (N,S, halogens)

Lassaigne test is used for this.

First sodium extract of the given organic compound is prepared.
A pea sized dry piece of sodium metal (freshly cut) is taken in an ignition tube and the tube is heated to melt the sodium metal piece to shining globule. Then a pinch of the organic compound is introduced in the tube. Then the tube is further heated first gently and strongly till the lower end of the tube becomes red hot. The tube is then plunged and broken in about 20 ml. of distilled water taken in porcelain dish. The solution is boiled for about 5 minutes and filtered. The filtrate obtained is known as sodium extract.

Test for Nitrogen

To 2ml of sodium extract, a little ferrous sulphate is added. The solution is boiled and a little dilute sulphuric acid is added. Appearance of prussian blue or green colouration indicates the presence of nitrogen in the compound.

Chapter 13A. Halogens

The Halogens are non-metals and form the 7th Group in the Periodic Table.

'Halogens' means 'salt formers' and the most common compound is sodium chloride which is found from natural evaporation as huge deposits of 'rock salt' or the even more abundant 'sea salt' in the seas and oceans.

Physical properties

• typical non-metals with relatively low melting points and boiling points.
• They are all poor conductors of heat and electricity - typical of non-metals.
• When solid they are brittle and crumbly e.g. iodine.

F Fluorine--- pale yellow gas

Cl Chlorine--- green gas

Br Bromine--- dark red liquid, brown vapour

I Iodine---- dark crumbly solid, purple vapour

At Astatine--- black solid, dark vapour

important trends down the Group with increasing atomic number
• The melting points and boiling increase steadily down the group (so the change in state at room temperature from gas ==> liquid ==> solid), this is because the weak electrical intermolecular attractive forces increase with increasing size of atom or molecule.
• They are all coloured non-metallic elements and the colour gets darker down the group.
• The size of the atom gets bigger as more inner electron shells are filled going down from one period to another.
Chemical Properties
• The atoms all have 7 outer electrons,
o they form singly charged negative ions e.g. chloride Cl- because they are one electron short of a noble gas electron structure. They gain one negative electron (reduction) to be stable and this gives a surplus electric charge of -1. These ions are called the halide ions, the bromide Br- and iodide I- ions.
o they form ionic compounds with metals e.g. sodium chloride Na+Cl-. (ionic bonding revision page)
o they form covalent compounds with non-metals and with themselves.
o The bonding in the molecule involves single covalent bonds e.g. hydrogen chloride HCl or H-Cl.
• The elements all exist as X2 or X-X, diatomic molecules where X represents the halogen atom.
• A more reactive halogen can displace a less reactive halogen from its salts .
• The reactivity decreases down the group .
• they are all TOXIC elements .
• Astatine is very radioactive, so difficult to study

Reaction with hydrogen H-2

• Halogens readily combine with hydrogen to form the hydrogen halides which are colourless gaseous covalent molecules. e.g. hydrogen + chlorine ==> hydrogen chloride
• H-2(g) + Cl-2(g) ==> 2HCl(g)
• The hydrogen halides dissolve in water to form very strong acids with solutions of pH1 e.g. hydrogen chloride forms hydrochloric acid in water HCl(aq) or H+Cl-(aq) because they are fully ionised in aqueous solution even though the original hydrogen halides were covalent. An acid is a substance that forms H+ ions in water.
• Bromine forms hydrogen bromide gas HBr(g), which dissolved in water forms hydrobromic acid HBr(aq). Iodine forms hydrogen iodide gas HI(g), which dissolved in water forms hydriodic acid HI(aq).

Reaction with Group 1 Alkali Metals Li, Na, K etc.

• Alkali metals burn very exothermically and vigorously when heated in chlorine to form colourless crystalline ionic salts e.g. NaCl or Na+Cl-.
• e.g. sodium + chlorine ==> sodium chloride
• 2Na(s) + Cl2(g) ==> 2NaCl(s)
• The sodium chloride is soluble in water to give a neutral solution pH 7, universal indicator is green. The salt is a typical ionic compound i.e. a brittle solid with a high melting point. Similarly potassium and bromine form potassium bromide KBr, or lithium and iodine form lithium iodide LiI.

Reaction with other metals
• If aluminium or iron is heated strongly in a stream of chlorine (or plunge the hot metal into a gas jar of chlorine carefully in a fume cupboard) the solid chloride is formed.
• aluminium + chlorine ==> aluminium chloride(white):
o 2Al(s) + 3Cl2(g) ==> 2AlCl3(s)
• iron + chlorine ==> iron(III) chloride(brown):
o 2Fe(s) + 3Cl2(g) ==> 2FeCl3(s)
• If the iron is repeated with bromine the reaction is less vigorous, with iodine there is little reaction, these also illustrate the halogen reactivity series.

One more orkut JEE community for chemistry

Came across the community today and joined the community.



This community is created to help the students who are preparing for different competitive exams viz ENGG/MEDICAL.Chemistry is always supposed to be more scoring in jee but there is great misconception that-IT IS A SUBJECT TO RATTOFY (CRAMMING).

This forum also welcome those people who have keen interest in chemistry and wish to get guidance.
Your queries and doubts of any level is most WELCOME and will be taken care of on priority basis.








NEW DELHI, DELHI, 110075, India
July 8, 2007 4:28 PM

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JEE 2008 Physical Chemistry Syllabus

Physical chemistry

General topics: Concept of atoms and molecules; Dalton’s atomic theory; Mole concept; Chemical formulae; Balanced chemical equations; Calculations (based on mole concept) involving common oxidation-reduction, neutralisation, and displacement reactions; Concentration in terms of mole fraction, molarity, molality and normality.

Gaseous and liquid states: Absolute scale of temperature, ideal gas equation; Deviation from ideality, van der Waals equation; Kinetic theory of gases, average, root mean square and most probable velocities and their relation with temperature; Law of partial pressures; Vapour pressure; Diffusion of gases.

Atomic structure and chemical bonding: Bohr model, spectrum of hydrogen atom, quantum numbers; Wave-particle duality, de Broglie hypothesis; Uncertainty principle; Qualitative quantum mechanical picture of hydrogen atom, shapes of s, p and d orbitals; Electronic configurations of elements (up to atomic number 36); Aufbau principle; Pauli’s exclusion principle and Hund’s rule; Orbital overlap and covalent bond; Hybridisation involving s, p and d orbitals only; Orbital energy diagrams for homonuclear diatomic species; Hydrogen bond; Polarity in molecules, dipole moment (qualitative aspects only); VSEPR model and shapes of molecules (linear, angular, triangular, square planar, pyramidal, square pyramidal, trigonal bipyramidal, tetrahedral and octahedral).

Energetics: First law of thermodynamics; Internal energy, work and heat, pressure-volume work; Enthalpy, Hess’s law; Heat of reaction, fusion and vapourization; Second law of thermodynamics; Entropy; Free energy; Criterion of spontaneity.

Chemical equilibrium: Law of mass action; Equilibrium constant, Le Chatelier's principle (effect of concentration, temperature and pressure); Significance of DG and DGo in chemical equilibrium; Solubility product, common ion effect, pH and buffer solutions; Acids and bases (Bronsted and Lewis concepts); Hydrolysis of salts.

Electrochemistry: Electrochemical cells and cell reactions; Standard electrode potentials; Nernst equation and its relation to DG; Electrochemical series, emf of galvanic cells; Faraday's laws of electrolysis; Electrolytic conductance, specific, equivalent and molar conductivity, Kohlrausch's law; Concentration cells.

Chemical kinetics: Rates of chemical reactions; Order of reactions; Rate constant; First order reactions; Temperature dependence of rate constant (Arrhenius equation).

Solid state: Classification of solids, crystalline state, seven crystal systems (cell parameters a, b, c, alpha, beta, gamma), close packed structure of solids (cubic), packing in fcc, bcc and hcp lattices; Nearest neighbours, ionic radii, simple ionic compounds, point defects.

Solutions: Raoult's law; Molecular weight determination from lowering of vapour pressure, elevation of boiling point and depression of freezing point.

Surface chemistry: Elementary concepts of adsorption (excluding adsorption isotherms); Colloids: types, methods of preparation and general properties; Elementary ideas of emulsions, surfactants and micelles (only definitions and examples).

Nuclear chemistry: Radioactivity: isotopes and isobars; Properties of alpha, beta and gamma rays; Kinetics of radioactive decay (decay series excluded), carbon dating; Stability of nuclei with respect to proton-neutron ratio; Brief discussion on fission and fusion reactions.

Saturday, December 8, 2007

JEE 2008 Syllabus Inorganic Chemistry

I am studying class XI and XII CBSE books of Jauhar along with TMH JEE Book of 2007. I am recording the sections and pages numbers where the specified topics are dealt with in these books for ready reference.

Such a reference seems to be essential for inorganic chemistry because the syllabus is not fitting into a simple chapter schemes of texts. For physical chemistry and organic chemistry each topic is distinct chapter in the books.

Inorganic Chemistry

Isolation/preparation and properties of the following non-metals:

Boron,XI Bk, Section 13.1, p.800-802
silicon, TMH JEE 2007 (TJ) page 13.4
nitrogen, XI Bk, Section 13.5,p.827-30
phosphorus, XII Bk, Sec 8.15
oxygen, XI, sec 13.7
sulphur and XII, 8.23,
halogens; XII, 8.26

Properties of allotropes of:
carbon (only diamond and graphite), XI, 812-814, XII, s 8.6.d.2, p 352
phosphorus and XII, 8.16, 369-70
sulphur.XII, 8.24, 389

Preparation and properties of the following compounds:

of sodium,

Oxides, XI, sec 12.6, 755-57, 763,764
peroxides, XI, 764
hydroxides, XI, 765
carbonates, XI, 767
chlorides and


chlorides and
sulphates of

Compound of Sodium and Potassium are covered in unit 14 in TJ


Oxides, XI, p774-76
hydroxides, XI 776
chlorides and XI 783
sulphates XI, 785


Oxides, XI, 774, 786
hydroxides, XI, 787
chlorides and
sulphates XI, 779, 788

Compound of Magnesium and Calcium are covered in unit 14 of TJ

diborane, XI, 13.2 806-10
boric acid and 804-5
borax; 802-4

aluminium chloride and
alums; - all in unit 14 TJ

oxides and XI , 13.4 818-21
oxyacid (carbonic acid);

silicones, XII, 8.10
silicates and 8.9
silicon carbide;

Nitrogen: XI 13.6
oxides, 833-36
oxyacids and 836-41
ammonia; 830-32

oxides, XII, p 367
oxyacids (phosphorus acid, phosphoric acid) and p 368, TJ p.15.17
phosphine; XII Sec 8.17, p370

ozone and Xi sec 13.9, 848-853
hydrogen peroxide; XI sec 11.9, 729-738
XII, p 385

hydrogen sulphide, XII p 364
oxides, XII sec 8.22.1 p 375
sulphurous acid, sec
sulphuric acid and, 8.25, p389
sodium thiosulphate; TJ p.15.21

hydrohalic acids, XII, 8.28.1 p 394
oxides and 394
oxyacids of chlorine, 95
bleaching powder; 8.29, 396

Xenon fluorides.XII, sec 8.33.A,

Transition elements (3d series):
Definition, XII, 9.1, 422
general characteristics, sec 9.2, 9.3
oxidation states and their stabilities, sec 9.3.6
colour (excluding the details of electronic transitions) and sec 9.3.7, Table 9.8 p430
calculation of spin-only magnetic moment; sec 9.3.9, p430

Preparation and properties of the following compounds:
Oxides and chlorides of tin and lead; XII, sec 8.11
Oxides, chlorides and sulphates of Fe2+, Cu2+ and Zn2+; XII sec 9.4, 9.11
Potassium permanganate, XII sec 9.11.6
potassium dichromate, 9.11.5
silver oxide,
silver nitrate, TJ p.14.9
silver thiosulphate.

Coordination compounds: XII, section 10
nomenclature of mononuclear coordination compounds, XII 10.1,2,3
cis-trans and ionisation isomerisms, 10.4
hybridization and geometries of mononuclear coordination compounds (linear, tetrahedral, square planar and octahedral).10.7

Ores and minerals: For this topic and topic of extraction metallurgy - refer Chapter X of Class XI book of Jauhar.

Commonly occurring ores and minerals of
zinc and

XI, sec 10.5

Extractive metallurgy: Chemical principles and reactions only (industrial details excluded); XI, 10.10
Carbon reduction method (iron and tin); 10.10.3.B.I.(i)
Self reduction method (copper and lead); 10.10.3.B.I.(vi)
Electrolytic reduction method (magnesium and aluminium); 10.10.3.B.III
Cyanide process (silver and gold). TJ p.17.6 (*gold is not there)

Principles of qualitative analysis: Ch. 18 of TMH JEE Book

Groups I to V (only Ag+, Hg2+, Cu2+, Pb2+, Bi3+, Fe3+, Cr3+, Al3+, Ca2+, Ba2+, Zn2+, Mn2+ and Mg2+);

Group I - TJp.18.3
Group II - 18.4
Group III- 18.5
Group IV - 18.5
Group V -- 18.6

Nitrate, 18.2
halides (excluding fluoride), 18.2
sulphate and 18.2
sulphide. 18.1

Except two or three topics all the topics are covered in the books. The specific items not covered can be accessed from one of the sites on the internet. I shall do it and post in the concerned chapter.

JEE 2008 Organic Chemistry Syllabus

Organic Chemistry


Hybridisation of carbon;
Sigma and pi-bonds;
Shapes of simple organic molecules;
Structural and geometrical isomerism;
Optical isomerism of compounds containing up to two asymmetric centres, (R,S and E,Z nomenclature excluded);
IUPAC nomenclature of simple organic compounds (only hydrocarbons, mono-functional and bi-functional compounds);
Conformations of ethane and butane (Newman projections);
Resonance and hyperconjugation;
Keto-enol tautomerism;
Determination of empirical and molecular formulae of simple compounds (only combustion method);
Hydrogen bonds: definition and their effects on physical properties of alcohols and carboxylic acids;
Inductive and resonance effects on acidity and basicity of organic acids and bases; Polarity and inductive effects in alkyl halides;
Reactive intermediates produced during homolytic and heterolytic bond cleavage; Formation, structure and stability of carbocations, carbanions and free radicals.

Preparation, properties and reactions of alkanes: Homologous series, physical properties of alkanes (melting points, boiling points and density); Combustion and halogenation of alkanes; Preparation of alkanes by Wurtz reaction and decarboxylation reactions.

Preparation, properties and reactions of alkenes and alkynes: Physical properties of alkenes and alkynes (boiling points, density and dipole moments); Acidity of alkynes; Acid catalysed hydration of alkenes and alkynes (excluding the stereochemistry of addition and elimination); Reactions of alkenes with KMnO4 and ozone; Reduction of alkenes and alkynes; Preparation of alkenes and alkynes by elimination reactions; Electrophilic addition reactions of alkenes with X2, HX, HOX and H2O (X=halogen); Addition reactions of alkynes; Metal acetylides.

Reactions of benzene: Structure and aromaticity; Electrophilic substitution reactions: halogenation, nitration, sulphonation, Friedel-Crafts alkylation and acylation; Effect of o-, m- and p-directing groups in monosubstituted benzenes.

Phenols: Acidity, electrophilic substitution reactions (halogenation, nitration and sulphonation); Reimer-Tieman reaction, Kolbe reaction.

Characteristic reactions of the following (including those mentioned above):
Alkyl halides: rearrangement reactions of alkyl carbocation, Grignard reactions, nucleophilic substitution reactions;

Alcohols: esterification, dehydration and oxidation, reaction with sodium, phosphorus halides, ZnCl2/concentrated HCl, conversion of alcohols into aldehydes and ketones;

Ethers:Preparation by Williamson's Synthesis;

Aldehydes and Ketones: oxidation, reduction, oxime and hydrazone formation; aldol condensation, Perkin reaction; Cannizzaro reaction; haloform reaction and nucleophilic addition reactions (Grignard addition);

Carboxylic acids: formation of esters, acid chlorides and amides, ester hydrolysis;

Amines: basicity of substituted anilines and aliphatic amines, preparation from nitro compounds, reaction with nitrous acid, azo coupling reaction of diazonium salts of aromatic amines, Sandmeyer and related reactions of diazonium salts; carbylamine reaction; Haloarenes: nucleophilic aromatic substitution in haloarenes and substituted haloarenes (excluding Benzyne mechanism and Cine substitution).

Carbohydrates: Classification; mono- and di-saccharides (glucose and sucrose); Oxidation, reduction, glycoside formation and hydrolysis of sucrose.
Amino acids and peptides: General structure (only primary structure for peptides) and physical properties.

Properties and uses of some important polymers: Natural rubber, cellulose, nylon, teflon and PVC.

Practical organic chemistry: Detection of elements (N, S, halogens); Detection and identification of the following functional groups: hydroxyl (alcoholic and phenolic), carbonyl (aldehyde and ketone), carboxyl, amino and nitro; Chemical methods of separation of mono-functional organic compounds from binary mixtures.

Sunday, December 2, 2007


Today, material is added to the chapter on Chemical Kinetics.

Material will be added to Chemical Equilibrium chapter and questions will be added in the practice sets blog.