Chougala Sir Fan Club

09/11/2015

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10/08/2013

Students aspiring to crack IES, IAS or any PSU examinations (after your degree) :
General Studies is a common and compulsory subject in IES and most of the PSU exams, and a must to crack IAS. It includes mainly current affairs, life sciences, history, geography, economy, constitution etc., for more updates on these, go for or Like IES General Studies.

www.facebook.com/iesgenstudies

This is a page for IES aspirants, as an aid tool to General Studies. Regular updates on questions and answers of previous years' question papers of IES (ESE) conducted by UPSC are discussed here. I hope this finds useful to maximum.

15/06/2013

Class XI NCERT Chemistry UNIT II

15/06/2013

CLASS XI NCERT CHEMISTRY UNIT 2

15/06/2013

CLASS XI NCERT UNIT 1

15/06/2013

CLASS XI NCERT CHEMISTRY UNIT 1

14/06/2013

Basic Chemistry Concepts CLASS XI NCERT

14/06/2013

14/06/2013

CLASS XI NCERT CHEMISTRY UNIT 1

14/06/2013

√ Rutherford Experiment

√ Rutherford with Geiger and Marsden studied the structure of the atom by firing a beam of alpha particles at gold atoms. This is the famous Gold foil experiment.

√ What they did?

√ They used a radioactive element (radon) which emit alpha particles and let them hit a very thin gold foil in an evacuated chamber. A ZnS screen was used as a detector for the alpha particles.

√ Results and Conclusion:-

√ A few alpha particles bounced directly back, indicating that they had struck something massive.

√ Rutherford proposed that most of the mass of atoms was concentrated in their centers.

√ This concentration of mass is now known as the nucleus.

√ Most of the particles were passed through it indicating most of the space of the foil doesn’t have that massive body.

√ Less than that, but more than the amount bounced back, were passed the foil changing its path. Alpha particles are He+ which is positively charged. So this massive body should be positively charged.

√ This concentration of mass/ massive body they have introduced is now known as the nucleus.


√ What Rutherford said about the experiment:-


* * It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you. On consideration, I realized that this scattering backward must be the result of a single collision, and when I made calculations I saw that it was impossible to get anything of that order of magnitude unless you took a system in which the greater part of the mass of the atom was concentrated in a minute nucleus. It was then that I had the idea of an atom with a minute massive center, carrying a charge. * *
—Ernest Rutherford

14/06/2013

Important definitions on Stereochemistry ► ► ►
1. Isomer = different Compounds that have the same molecular formula.
2. Stereoisomer = Isomers which have atoms that differ only by their orientation in space. Unlike constitutional isomers, corresponding atoms in stereoisomers exhibit the same connectivity.
3. Super posable = A term that describes the ability to precisely overlap one object over another. Only identical objects are superposable, everything else is non-superposable
4. Chiral =A molecule is chiral if it is not superposable on its mirror image.
5. Achiral = A molecule is achiral if it is superposable on its mirror image
6. Meso = A molecule is meso if it is achiral and contains two or more stereocenters.
7. Enantiomer = Stereoisomers that are non-superposable mirror images.
8. Diastereoisomer = Stereoisomers that are non-superposable, but are not mirror images.
9. Constitutional isomer = Isomers which contain atoms that differ in connectivity.

14/06/2013

Shapes of molecules and their number of electron pairs
Shape ------------------------------Bonding pairs----------------------------lone pairs--------------------Example
1.Linear 2 0 BeCl2
2 3 XeF2

2.Bent 2 2 H2O
2 1 en NO2

3.Trigonal Planer 3 0 BCl3
4. Trigonal pyramid 3 1 NH3
5.T shape 3 2 ClF3
6. tetragonal 4 0 CH4
7. See saw 4 1 SF4
(distorted tetrahedran)
8. Squre planer 4 2 XeF4
9. Trigonal Bipyramid 5 0 PCl5
10. Squre Pyramidal 5 1 ClF5
11. Octahedral 6 0 SF6
12.Pentagonal Bipyramidal 7 0 IF7