UPSEE: Important Questions and Study notes for Chemical Bonding

The chapter ‘Chemical Bonding’ is a very important part of Chemistry in the syllabus of UPSEE/UPTU entrance examination 2018. About 2-3 questions have always been asked from this chapter in the examination. You will come to know that the levels of the questions are bit low as compared to JEE Main.

In this article, UPSEE/UPTU aspirants will get study notes on Chemical Bonding based on the latest syllabus of the examination. Apart from previous year questions, we are also providing few more questions from the mentioned topics for the practice purpose. Developing a good command on this chapter will help you in various chapters to solve the indirect involvement of the various concepts like Hybridisation, Valence Shell Electron Pair Repulsion (VSEPR) Theory and concepts related to diamagnetic and paramagnetic molecules.

UPSEE/UPTU Chemistry Syllabus: 2017 - 2018

Students can study the following topics here:

1. Chemical bonding

2. Types of chemical bond i.e., Covalent, ionic and Metallic bond

3. Hydrogen bond

4. Hybridisation

5. Important conditions for hybridization

6. Types of hybridization

7. Shape of some simple molecules including number of electron pairs, bonds pairs, lone pairs, geometry of molecule and examples

8. Valence Shell Electron Pair Repulsion (VSEPR) Theory

Important Concepts:

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VALENCE SHELL ELECTRON PAIR REPULSION (VSEPR) THEORY

Main Postulates of VSEPR Theory:

1. The shape of a molecule depends upon the number of valence shell electron pairs (bonded or non-bonded) around the central atom.

2. Pairs of electrons in the valence shell repel one another since their electron clouds are negatively charged.

3. These pairs of electrons tend to occupy such positions in space that minimise repulsion and thus maximize distance between them.

4. The valence shell is taken as a sphere with the electron pairs localising on the spherical surface at maximum distance from one another.

5. A multiple bond is treated as if it is a single electron pair and the two or three electr on pairs of a multiple bond are treated as a single super pair.

6. Where two or more resonance structures can represent a molecule, the VSEPR model is applicable to any such structure.

Shape of molecules in which the central atom has no lone pair of electrons is given in the table below:

Shapes of some simple molecules/ions with central ions having one or more lone pairs of electrons are given below:

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Some previous years’ solved questions are given below:

Question 1:

Solution 1:

Hence, the correct option is (c).

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Question 2:

The pair of molecules forming strongest hydrogen bonds are

(a) HCOOH and CH3COOH

(b) CH3COCH3 and CHCI3

(c) H2O and H2

(d) SiF6 and SiH4

Solution 2:

Hence, the correct option is (a).

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Question 3:

What is the structure of XeF6?

(a) Tetrahedral

(b) Distorted octahedral

(c) Octahedral

(d) None of these

Solution 3:

The structure of XeF6

Hybridisation = sp3d2

Due to the presence of one lone pair of electron, XeF6 has distorted octahedral geometry.

Hence, the correct option is (b).

UPSEE: Important Questions and Preparation Tips – Chemical Kinetics (Part 2)

Question 4:

The shape of XeO2F2 molecule is

(a) Trigonal bipyramidal

(b) Square planar

(c) Tetrahedral

(d) See-saw

Solution 4:

Hence, the correct option is (d).

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Question 5:

Which one of the following has (have) octahedral geometry?

(i) SbCl6-

(ii) SnCl62-

(iii) XeF6

(iv) IO65-

(a) (i), (ii) & (iii)

(b) (i), (ii) & (iv)

(c) (ii), (iii) & (iv)

(d) All of these

Solution 5:

XeF6 has distortion and become pentagonal bipyramid with one lone pair.

SnCl62- = 4 + 6(7) + 2 = 48

6 sets of electron – Octahedral

Hence, the correct option is (b).

Question 6:

Solution 6:

The bond angle depends on bond pair repulsion. More electronegative is the element more is bond pair repulsion and more is the bond angle. Among P, As and Sb, P is the most electronegative element so, it has highest bond angle among them.

Hence, the correct option is (d).

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Conclusion:

These notes will help you to grasp all the important concepts related to chapter Chemical Bonding. With the help of previous years’ solved questions given here aspirants can easily get familiar with the difficulty level of the question paper. It will also help you to score full marks in the questions asked from this chapter.

Mathematics all chapters complete notes for UPSEE/UPTU 2018

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