Question

How many electrons in a copper atom $\left({}^{29}\mathrm{Cu}\right)$ have$(\mathrm{n}+\mathrm{l})=4$

Answer 1

Copper:

• Copper is a metal.
• It s soft, malleable and ductile.
• It has high thermal and electrical conductivity.
• It is used for making electrical wiring, generators, motors and electronic goods such as radios and TVs.

Electrons in $(\mathrm{n}+\mathrm{l})=4$

Step 1: Electronic configuration of copper

• The atomic number of Copper is $29$.
• Copper is a transition metal, the electronic configuration of copper is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{1}3{\mathrm{d}}^{10}$

Step 2: Explanation of terms in $(\mathrm{n}+\mathrm{l})=4$:

• $(\mathrm{n}+\mathrm{l})=4$, In this $\mathrm{n}$is the principal quantum number and $\mathrm{l}$ is the azimuthal quantum number.

$$\begin{gathered} \mathrm{s}-\mathrm{orbital}\mathrm{l}=0 \\ \mathrm{p}-\mathrm{orbital}\mathrm{l}=1 \\ \mathrm{d}-\mathrm{orbital}\mathrm{l}=2 \\ \mathrm{f}-\mathrm{orbital}\mathrm{l}=3 \end{gathered}$$

Step 3: Finding the total number of electrons:

$$\begin{gathered} 1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^{6}3{\mathrm{s}}^{2}3{\mathrm{p}}^{6}4{\mathrm{s}}^{1}3{\mathrm{d}}^{10} \\ 1{\mathrm{s}}^2=(\mathrm{n}+\mathrm{l})2{\mathrm{s}}^2=(\mathrm{n}+\mathrm{l})2{\mathrm{p}}^6=(\mathrm{n}+\mathrm{l}) \\ =(1+0)=(2+0)=2+1 \\ =1\ne 4=0\ne 4=3\ne 4 \\ 3{\mathrm{s}}^2=(\mathrm{n}+\mathrm{l})3{\mathrm{p}}^6=(\mathrm{n}+\mathrm{l})4{\mathrm{s}}^1=(\mathrm{n}+\mathrm{l})3{\mathrm{d}}^{10}=(\mathrm{n}+\mathrm{l}) \\ =(3+0)=(3+1)=4+0=3+2 \\ =3\ne 4=4=4=5\ne 4 \\ \mathrm{So},\mathrm{only}3{\mathrm{p}}^{6}4{\mathrm{s}}^1\mathrm{satisfies}(\mathrm{n}+\mathrm{l})=4 \end{gathered}$$

So, totally $7$electrons are present in the copper.