Questions: What is the ground state electron configuration of molybdenum? [A r] 4 s^1 3 d^5 [K r] 5 s^2 4 d^4 [Kr] 5 s^1 4 d^5 [Kr] 4 d^6 [Ar] 4 s^2 3 d^4

Transcript text: What is the ground state electron configuration of molybdenum? $[A r] 4 s^{1} 3 d^{5}$ $[K r] 5 s^{2} 4 d^{4}$ $[\mathrm{Kr}] 5 \mathrm{~s}^{1} 4 \mathrm{~d}^{5}$ $[\mathrm{Kr}] 4 \mathrm{~d}^{6}$ $[\mathrm{Ar}] 4 \mathrm{~s}^{2} 3 \mathrm{~d}^{4}$

Solution

Solution Steps

Step 1: Understanding Electron Configuration

Electron configuration describes the distribution of electrons in an atom's orbitals. The ground state configuration is the lowest energy arrangement of electrons.

Step 2: Identifying Molybdenum's Atomic Number

Molybdenum (Mo) has an atomic number of 42, meaning it has 42 electrons.

Step 3: Determining the Correct Configuration

The electron configuration for molybdenum should be determined by filling the orbitals in order of increasing energy, following the Aufbau principle, Hund's rule, and the Pauli exclusion principle.

Step 4: Applying the Aufbau Principle

According to the Aufbau principle, electrons fill orbitals starting from the lowest energy level. For molybdenum, the expected configuration would be:

Fill the 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, and then 4d orbitals.

Step 5: Considering Exceptions

Molybdenum is an exception to the typical filling order. Instead of filling the 5s orbital completely before the 4d, one electron from the 5s is used to half-fill the 4d orbital, resulting in a more stable configuration.

Step 6: Writing the Configuration

The correct ground state electron configuration for molybdenum is: \[ [\mathrm{Kr}] 5\mathrm{s}^{1} 4\mathrm{d}^{5} \]