Question

Which of the following set of quantum numbers (n, l, m, s) represents the valence electron in a copper atom? (atomic number of Cu = 29)

• A. $\mathrm{n}=4,\mathrm{l}=1,\mathrm{m}=0,\mathrm{s}=+\frac{1}{2}$
• B. $\mathrm{n}=4,\mathrm{l}=1,\mathrm{m}=+2,\mathrm{s}=+\frac{1}{2}$
• C. $\mathrm{n}=4,\mathrm{l}=0,\mathrm{m}=0,\mathrm{s}=+\frac{1}{2}$
• D. $\mathrm{n}=4,\mathrm{l}=0,\mathrm{m}=+2,\mathrm{s}=+\frac{1}{2}$

Answer 1

The correct option is C

$\mathrm{n}=4,\mathrm{l}=0,\mathrm{m}=0,\mathrm{s}=+\frac{1}{2}$

The explanation for the correct answer:

(C) $\mathrm{n}=4,\mathrm{l}=0,\mathrm{m}=0,\mathrm{s}=+\frac{1}{2}$

The electronic configuration of the copper

• The electronic configuration of the copper atom ($\mathrm{Cu}$) is

$1{\mathrm{s}}^2,2{\mathrm{s}}^2,2{\mathrm{p}}^6,3{\mathrm{s}}^2,3{\mathrm{d}}^{10},4{\mathrm{s}}^1$

Principal Quantum number:

• Principal Quantum number represents the shell number of the electron.
• Symbol of principal quantum number is $\mathrm{n}$ .
• Value of principal quantum number for valence shell of Copper is $\mathrm{n}=4$

Azimuthal Quantum number:

• Azimuthal Quantum number represents the subshell of the electron.
• Symbol of Azimuthal Quantum number is $\mathrm{l}$.
• Value of azimuthal quantum number for valence shell of Copper is $\mathrm{l}=0$

Magnetic Quantum number:

• Magnetic Quantum number represents the orbital of the electron.
• Symbol of Magnetic Quantum number is $\mathrm{m}$.
• Value of magnetic quantum number for valence shell of Copper is$\mathrm{m}=0$

Spin Quantum Number:

• Spin Quantum Number represents whether the electron spins clockwise or anti-clockwise and the symbol is $\mathrm{s}$.
• Its value is either $+\frac{1}{2}$ or $-\frac{1}{2}$.
• Value of spin quantum number for valence shell of Copper is $\mathrm{s}=+\frac{1}{2}$

The explanation for the incorrect answer:

(A) $\mathrm{n}=4,\mathrm{l}=1,\mathrm{m}=0,\mathrm{s}=+\frac{1}{2}$

• It is incorrect answer because the value of azimuthal quantum number for valence shell of Copper is $\mathrm{l}=0$.

(B) $\mathrm{n}=4,\mathrm{l}=1,\mathrm{m}=+2,\mathrm{s}=+\frac{1}{2}$

• It is incorrect answer because the value of azimuthal quantum number for valence shell of Copper is $\mathrm{l}=0$.
• It is incorrect answer because the value of magnetic quantum number for valence shell of Copper is$\mathrm{m}=0$

(D) $\mathrm{m}=4,\mathrm{l}=0,\mathrm{m}=+2,\mathrm{s}=+\frac{1}{2}$

• It is incorrect answer because the value of magnetic quantum number for valence shell of Copper is$\mathrm{m}=0$

Hence, the correct answer is (C) $\mathrm{n}=4,\mathrm{l}=0,\mathrm{m}=0,\mathrm{s}=+\frac{1}{2}$.