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Consider a N2 molecule in its first excited electronic state, that is, when an electron in the highest occupied molecular orbital is promoted to the lowest empty molecular orbital. (a) Identify the molecular orbitals involved and sketch a diagram to show the transition. (b) Compare the bond order and bond length of N2* with N2, where the asterisk denotes the excited molecule. (c) Is N2* diamagnetic or paramagnetic? (d) When N2* loses its excess energy and converts to the ground state N2, it emits a photon of wavelength 470 nm, which makes up part of the auroras lights. Calculate the energy difference between these levels.
(a)
Interpretation:
The molecular orbital involved in transition should be identified and to sketch the transition. Bond order of 
and 
should be found and the bond length should be compared. The magnetic properties of should be found out. The energy difference of the given transition should be determined
Concept Introduction:
- In molecular orbital theory, when the bonding takes place the atomic orbitals that take part combine to get a new orbital that has the properties of the whole molecule. The newly formed orbitals are known as molecular orbitals
- The bond order gives an idea about the stability of a molecule. It can be calculated using the molecular orbital theory. The stability of a molecule increase as the bond order increases.
- Paramagnetic species contains at least one unpaired electrons and can be attracted towards magnetic fields. Diamagnetic species does have any unpaired electrons. That is spins of all the electrons are paired. It slightly repelled towards the magnetic fields
To identify: molecular orbital involved in transition and to sketch the transition.
Answer to Problem 10.113QP
The transition sketch is,
Explanation of Solution
In molecular orbital theory, when the bonding takes place the atomic orbitals that take part combine to get a new orbital that has the properties of the whole molecule. The newly formed orbitals are known as molecular orbitals and only contain a maximum of two electrons. The number of newly formed molecular orbital is equal to the number of atomic orbitals involved in the bonding.
There are two types of molecular orbitals,
- a) Bonding molecular orbitals: sharing of electron density is between the nuclei and has comparatively lower energy and fills first.
- b) Antibonding molecular orbitals: Two nuclei is pulled by the electrons density in opposite direction and has higher energy comparing to bonding molecular orbital.
Molecular orbital diagram of is given below
Figure 1
In the ground state of the electrons are in 
orbital when the gets excited by getting energy the electron move to 
orbitals.
The diagram that showing transition is given below,
(b)
Interpretation:
The molecular orbital involved in transition should be identified and to sketch the transition. Bond order of and should be found and the bond length should be compared. The magnetic properties of should be found out. The energy difference of the given transition should be determined
Concept Introduction:
- In molecular orbital theory, when the bonding takes place the atomic orbitals that take part combine to get a new orbital that has the properties of the whole molecule. The newly formed orbitals are known as molecular orbitals
- The bond order gives an idea about the stability of a molecule. It can be calculated using the molecular orbital theory. The stability of a molecule increase as the bond order increases.
- Paramagnetic species contains at least one unpaired electrons and can be attracted towards magnetic fields. Diamagnetic species does have any unpaired electrons. That is spins of all the electrons are paired. It slightly repelled towards the magnetic fields
To identify: Bond of order of and. Also to compare its bond length
Answer to Problem 10.113QP
Bond order of and is 3 and 2 respectively. Also the bond length of is longer than .
Explanation of Solution
Electronic configuration of excited nitrogen molecule is 
The bond order gives an idea about the stability of a molecule. It can be calculated using the molecular orbital theory. The stability of a molecule increase as the bond order increases.
Electronic configuration of excited nitrogen molecule is 
The bond order gives an idea about the stability of a molecule. It can be calculated using the molecular orbital theory. The stability of a molecule increase as the bond order increases.
Bond order of is 3 whereas is 2.
Therefore, the bond length of is longer than .
(c)
Interpretation:
The molecular orbital involved in transition should be identified and to sketch the transition. Bond order of and should be found and the bond length should be compared. The magnetic properties of should be found out. The energy difference of the given transition should be determined
Concept Introduction:
- In molecular orbital theory, when the bonding takes place the atomic orbitals that take part combine to get a new orbital that has the properties of the whole molecule. The newly formed orbitals are known as molecular orbitals
- The bond order gives an idea about the stability of a molecule. It can be calculated using the molecular orbital theory. The stability of a molecule increase as the bond order increases.
- Paramagnetic species contains at least one unpaired electrons and can be attracted towards magnetic fields. Diamagnetic species does have any unpaired electrons. That is spins of all the electrons are paired. It slightly repelled towards the magnetic fields
To identify: The magnetic properties of
Answer to Problem 10.113QP
is diamagnetic
Explanation of Solution
Paramagnetic species contains at least one unpaired electrons and can be attracted towards magnetic fields. Diamagnetic species does have any unpaired electrons. That is spins of all the electrons are paired. It slightly repelled towards the magnetic fields.
Electronic configuration of excited nitrogen molecule is
Even though there are unpaired electrons, the spin of the electrons was not change in the time of transition. All the electrons are paired so it is diamagnetic.
(d)
Interpretation:
The molecular orbital involved in transition should be identified and to sketch the transition. Bond order of and should be found and the bond length should be compared. The magnetic properties of should be found out. The energy difference of the given transition should be determined
Concept Introduction:
- In molecular orbital theory, when the bonding takes place the atomic orbitals that take part combine to get a new orbital that has the properties of the whole molecule. The newly formed orbitals are known as molecular orbitals
- The bond order gives an idea about the stability of a molecule. It can be calculated using the molecular orbital theory. The stability of a molecule increase as the bond order increases.
- Paramagnetic species contains at least one unpaired electrons and can be attracted towards magnetic fields. Diamagnetic species does have any unpaired electrons. That is spins of all the electrons are paired. It slightly repelled towards the magnetic fields
To determine: The energy difference of the given transition.
Answer to Problem 10.113QP
The energy difference of the given transition is 
Explanation of Solution
The energy of light is calculated below.
Given,
The wavelength of light is 
.
Planck’s constant is 
Speed of the light is 
The energy of light is calculated is calculated by the equation,
Substituting the given values in the equation,
The energy difference of the given transition is
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Chapter 10 Solutions
CHEMISTRY-ALEK 360 ACCES 1 SEMESTER ONL
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