Question

For the valence electron in copper, the quantum numbers are:
A.$n = 4,l = 0,m = 0,s = + \dfrac{1}{2}$
B.$n = 4,l = 0,m = + 2,s = + \dfrac{1}{2}$
C.$n = 4,l = 1,m = 0,s = + \dfrac{1}{2}$
D.$n = 4,l = 1,m = 0,s = + \dfrac{1}{2}$

Answer 1

Hint: Write the electronic configuration of copper, find the valence electron.Then we have to find the quantum numbers for the valence electron of copper.

Complete step by step answer:
There are 4 quantum numbers namely:
n – Also known as Principal Quantum number, it specifies the shell number of the electron. Its value ranges from 1 to the number of the outermost shell of the atom that has electrons.
l – Also known as Azimuthal Quantum number, it specifies the subshell of the electron. The value of l ranges from 0 to n – 1. It also specifies the shape of the orbital.
m – Also known as the Magnetic Quantum number, it specifies the orbital of the electron. The values of ml range from −l to l, with integer intervals
s - Also known as the Spin Quantum Number, it specifies whether the electron spins clockwise or anti – clockwise. Its value is either $ + \dfrac{1}{2}or - \dfrac{1}{2}$.
These values serve as an address for an electron.
Now, we have to find the quantum numbers for the valence electron of copper. For this, first we will write down the electronic configuration of copper.
$\begin{gathered}
   \Rightarrow Cu(29) = 2,8,18,1 \\
   \Rightarrow 1{s^2},2{s^2}2{p^6},3{s^2},3{p^6},3{d^{10}},4{s^1} \\
\end{gathered} $
Therefore, the quantum numbers for $4s^1$ electron are:

\[ \Rightarrow \begin{array}{*{20}{l}}
  {n = 4,l = 0,m = 0,s = + \dfrac{1}{2}} \\
  \;
\end{array}\]

Hence the option A is correct.

Note:
The values for all the quantum numbers have their own meaning.
n will be the shell number.
l will be the subshell number, this means, l=0 for s, l=1 for p, l=2 for d and l=3 for f.
m will be the orbital number. m=0 for s, m= -1 to +1 for p, m=-2 to +2 for d and m=-3 to +3 for f.
s will tell about the spin of electrons. $s = + \dfrac{1}{2}$ for clockwise spin and $s = - \dfrac{1}{2}$ for anti – clockwise spin.
Always write the electronic configuration keeping in mind the stability of the atom.