Question

Consider the argon atom. For how many electrons does this atom have \( m_l = 1 \)?

• A. 2
• B. 4
• C. 6
• D. 12

Hint:

Remember, the magnetic quantum number \( m_l \) defines the orientation of the orbital, and for any \( p \)-orbital (\( l = 1 \)), there are three possible values for \( m_l \), which are \( -1, 0, +1 \).

Answer 1

The Correct Option is B

For the given question, we need to consider the electron configuration of the Argon atom (\( \text{Ar} \)) and find out how many electrons have \( m_l = 1 \). The electron configuration for Argon (\( \text{Ar} \)) is as follows: \[ 1s^2 \, 2s^2 \, 2p^6 \, 3s^2 \, 3p^6 \] Now, let's focus on the \( 2p \) and \( 3p \) orbitals because the question specifically asks about the electrons with \( m_l = 1 \).
The \( 2p \) orbital has three possible values for \( m_l \): \( m_l = -1, 0, 1 \). The number of electrons in the \( 2p \) orbital is 6, and these electrons are distributed over the three values of \( m_l \), with two electrons having \( m_l = 1 \).
The \( 3p \) orbital also has three possible values for \( m_l \): \( m_l = -1, 0, 1 \). The number of electrons in the \( 3p \) orbital is 6, and these electrons are distributed over the three values of \( m_l \), with two electrons having \( m_l = 1 \).

Thus, there are a total of 4 electrons with \( m_l = 1 \), two electrons from the \( 2p \) orbital and two electrons from the \( 3p \) orbital.

Thus, the correct answer is (B) 4.