Question

The relative atomic masses of two isotopes of an element are 15.9936 and 17.0036 amu. Calculate (A) the number of electrons (B) number of protons (C) number of neutrons(D) mass number. Also mention the quantum numbers of the valence electron.

Answer 1

The atomic number of element will be $\frac{15.9936}{2}=8$

(A) No. of $e^{-}=8$

(B) No. of protons$=8$

(C) No. of neutrons in isotope of lower atomic mass $\left(1\right)=16-8=8$

No. of neutrons in isotope of higher atomic mass $\left(2\right)=17-8=9$

(D) Mass number of $\left(1\right)=16$

mass number of $\left(2\right)=17$

(E) In valence shell it will have ${4e}^{-}$s

In ${2P}_x:n=2,l=-1,m=-1,s=+\frac{1}{2}\&-\frac{1}{2}$

In ${2P}_y:n=2,l=-1,m=0,s=\frac{+1/2}{-1/2}$

In ${2P}_z:n=2,l=-1,m=-1,s=\frac{+1/2}{-1/2}$