Unit-1
Question Bank
Q-Define Atomic Orbitals.
A- Atomic Orbitals is the mathematical function which is responsible for the determination of location and wave like behavior of an electron in the atom. Atomic orbital is the region where the electrons are present in the atoms. Hence the orbitals in an atom is identified from their unique values i.e.; n, l, m.
Q-Define Molecular Orbitals.
A- Molecular Orbital is the mathematical function which is responsible for the determination of location and wave like behavior of an electron in the molecule. In molecular orbital, the electrons are allowed to interact with more than one atomic nucleus at a time.
Q-Mention the rules to be followed for LCAO.
A- Rules for the Linear Combination of Atomic Orbital are:-
- The combining atoms should have the same symmetry along the molecular axis for proper combination. e.g. All the sub-orbitals of 2p have same energy but still, the 2pz orbital of an atom can only combine with a 2pz orbital of another atom but cannot combine with 2px and 2py orbital as they have a different axis of symmetry.
- The two atomic orbital will combine to form molecular orbital. Greater is the extend of overlap of atomic orbital; greater will be the nuclear density.
- The combining atomic orbital must be of equal energy or approximately same energy.
Q-Explain the energy level Homonuclear diatomic molecule & calculate the evolved energy.
A- H2 molecule consist of two H atoms and their two electrons. Two 1s orbitals give two MOs- one bonding that is σ and another one is antibonding that is σ*. The bonding orbital is in lower in energy state, the two electron occupies the bonding MO. The MO electron configuration of H2 molecule is written as (σ1s) 2.
Energy evolved =
[No. Of electron in BMO (-) + No. Of electron in Anti Bonding Molecular Orbital * (+)]
=2*(- ) + 0*(+ )
= -2
This evolved energy is called as stabilization energy.
The molecule is stable so it is diamagnetic.
Q-Explain Carbon Monoxide molecule with its electronic configuration.
A- Carbon Monoxide Molecule (CO)
CO is the hetronuclear diatomic molecule. This molecule is formed by the combination of carbon and oxygen atom. Electronic configuration of carbon atom is 1s2, 2s2, 2p2 and that of oxygen is 1s2, 2s2, 2p4
Q-Explain O2 molecule with Molecular Orbital diagram.
Q-Explain N2 molecule with Molecular Orbital diagram.
Q- Explain the energy level of Benzene molecule.
A- In the figure given below the increasing energy level the bottom three orbital are all bonding orbital while the top 3 orbital are anti bonding orbital.
Q- Explain the benzene molecule at its lowest molecular orbital state.
A- The Benzene System has zero nodes at its lowest energy molecular orbital.
- All p orbital are aligned with phases pointing in the same direction.
- Nodes are absent between orbital.
- In this orbital, electrons are delocalized over the length of molecule, resulting in greatest lowering of energy.
Q- Explain the bonding and anti bonding systems of Benzene molecule.
Q- What are the conditions at which splitting are effected in Crystal Field Theory?
A- The splitting can be affected by following factors:-
• Metal ion nature
• Metals oxidation state.
• Ligand arrangement around the metal ion
• Metal coordination number
Q- Explain the effect of doping on N-type material.
A- The effect of doping on an N-type material is as follows −
- On addition of Arsenic to pure Silicon, the crystal becomes an N-type material.
- Arsenic atom has additional electrons or negative charges that do not take part in the process of covalent bonding.
- These impurities give up or donate, one electron to the crystal and they are referred to as donor impurities.
- An N-type material has extra or free electrons than an intrinsic material.
- An N-type material is not negatively charged. Actually all of its atoms are all electrically neutral.
- These extra electrons do not take part in the covalent bonding process. They are free to move about through the crystal structure.
- An N-type extrinsic silicon crystal will go into conduction with only 0.005eV of energy applied.
- Only 0.7eV is required to move electrons of intrinsic crystal from the valence band into the conduction band.