Question

In the first transition series the incoming electron enters the :
(a) 4d-orbital (b) 3d-orbital (c) 5d-orbital (d) 6d-orbital

Answer 1

3d-orbital..............

Answer 2

Answer:

3d-orbital. (b)

Explanation:

Molecular orbital theory (often abbreviated to MOT) is a theory of chemical bonding developed  by F. Hund and R.S. Mulliken in the early 20th century to explain the structure and properties of various molecules.

Characteristics of molecular orbital theory:

1. Atomic orbitals overlap to form new orbitals called molecular orbitals.
2. When two atomic orbitals overlap, they lose their identity and form a new orbital called a molecular orbital.
3. Electrons in  molecules fill to new energy states called molecular orbitals, just like electrons in atoms fill to energy states called atomic orbitals.  
4. The probability of finding the molecular electron distribution  around the core group  is given by the molecular orbitals. Two bonding atomic orbitals must have similar energy values ​​and orientations. For example, 1 can be combined with 1, but not with 2.
5. The number of molecular orbitals formed is equal to the number of bonded atomic orbitals. The shape of the molecular orbital formed depends on the shape of the bonding atomic orbitals.

According to molecular orbital theory, orbitals are filled according to the following rules:

Aufbau's Principle: Molecular orbitals are filled in  order of increasing energy levels. Hence the first transition series elements fill up the lowest energy 3d orbital.

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