Molecular Orbital Theory tips to solve questions

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Importance of time in the competitive exam-
There is very much Importance of time in NEET , JEE and other competitive exams, management of time plays an important role for the topper students as they can solve the paper with efficiency and in low pressure or stress although time management is not like god in such type of exams, you should be also aware of the tricks and tips that you can apply for some type of questions, it can save your time so that you can invest that in other tough questions.

Some students waste the important minutes of exams for the type of simple questions, So here is the tip to solve the MOT questions very easily, I will try to explain the trick in very simple words so everyone can consider it and apply it in your exam-


We will understand 3 types of questions here, which often come in competitive exams-

[A] Question- Compare the bond order between N^-3 and O^-2?

Here is the question, we have two different types of atoms that are Nitrogen and Oxygen.

First of all, you have to remember this simple table of bond orders up to the atoms that have maximum 20 electrons ( According to the course)



Now Let's solve the question-
Step -1 Calculate the total number of electrons of the particular atom
[1] N^-3 has 14+3 = 17 electrons 
[2] O^-2 has 16+2 = 18 electrons

Step-2 Look into the table that you have remembered earlier to get the correct bond order
[1] In the case of N^-3, and order will be 1.5
[2] In the case of O^-2, bond order will be 1

Look here you can solve the question with traditional formula, but in fact, it will waste yours a lot of time, I always consider these tricks to solve the MOT questions.




[B] Question - Compare the bond length of following-
       
      O2, O2^+, O2^-, O2^+2, and O2^-2

Here in the question, it is asked about the length of bonds, in general, we know that O2 molecule has 2 bonds but what about the other excited states, here is the work of MOT concept-


  •  Bond order is inversely proportional to the bond length means as the bond order will increase, bond strength will also increase but the bond length will decrease.


Step-1 Calculate the number of electrons for all the molecules that are 16, 15, 17, 14, 18 respectively

Step -2 look into the table and get the correct bond order that is 2,2.5,1.5,3,1.

Now make these inputs in the order- 3>2.5>2>1.5>1 and tick your correct answer.

[C] Determine the magnetic nature of the following elements-

     N2^-2 and O2

Two types of magnetic nature often asked in this type of question
[a] paramagnetic and [b] Diamagnetic

In this type of question, you only have to calculate all the electrons of the molecule and if the total electron number is in-
Even number means the element is Diamagnetic 
Odd number means the element is Paramagnetic.

NOTE- Elements that have 10 and 16 electrons also consider as paramagnetic although the total electron number is an even number.

Hey Fellows, how is it going?
  • So comment down below and tell me how helpful it was for you.
  • As per my thoughts, it will save yours lots of time and also you can do copy and paste in your own device from here so that you can read this easily.





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