Values of the four quantum numbers for the last electron in the atom are n=4, l=1, m=+1 and s=-1/2. Atomic number of the atom will be

Options

A. 22
B. 32
C. 33
D. 36

Explanation

To determine the atomic number of the atom based on the given quantum numbers (n=4, l=1, m=+1, s=-1/2), we can follow these steps:

### Step 1: Identify the Electron Shell and Subshell
The principal quantum number \( n = 4 \) indicates that the electron is in the fourth energy level or shell. The azimuthal quantum number \( l = 1 \) corresponds to the p subshell (since \( l = 0 \) is s, \( l = 1 \) is p, \( l = 2 \) is d, and \( l = 3 \) is f).

### Step 2: Determine the Orbital
The magnetic quantum number \( m = +1 \) indicates that the electron is in one of the three orbitals of the p subshell. The possible values of \( m \) for \( l = 1 \) are -1, 0, and +1. Thus, the electron is in the 4p orbital.

### Step 3: Determine the Spin of the Electron
The spin quantum number \( s = -1/2 \) indicates that the electron has a spin in the opposite direction (down spin).

### Step 4: Count the Electrons in the Configuration
Since we know that the last electron is in the 4p orbital, we can deduce the electron configuration leading up to this point. The complete electron configuration for an atom with the last electron in the 4p subshell is:

- 1s²
- 2s²
- 2p⁶
- 3s²
- 3p⁶
- 4s²
- 3d¹⁰
- 4p⁶ (for the last electron)

### Step 5: Calculate the Atomic Number
To find the atomic number, we need to count the total number of electrons:

- 1s² = 2 electrons
- 2s² = 2 electrons
- 2p⁶ = 6 electrons
- 3s² = 2 electrons
- 3p⁶ = 6 electrons
- 4s² = 2 electrons
- 3d¹⁰ = 10 electrons
- 4p⁶ = 6 electrons

Now, summing these gives:
\[ 2 + 2 + 6 + 2 + 6 + 2 + 10 + 6 = 36 \]

Thus, the atomic number of the atom is **36**.