Question

Using the known values for haydrogen atom, calculate. (a) radius of thirdj orbit for Li^(+2). (b) speed of electron in fourth orbit for He^+ . (c ) angular momentum of electron in 3rd orbit of He^+.

Answer 1

The angular momentum of electron in the 3rd orbit is 1.095  × 10^6 ms−1

Explanation:

(a) Z = 3f or Li2+

Further, we know that

rn = f  or  n^2/  2  a0

Substituting n = 3,

Z = 3 and a0 = 0.529 Å we have

r3f or Li+2=  (3)^2  / (3)  (0.529) Å = 1.587 Å

b. Z=2 for He+. Also , we know that

vn = z / nv1

Substituting n = 4

z = 2

and V1 = 2.19 × 10^6 ms−1

We get

V4 for He+ = (2 / 4) (2.19 × 10^6)ms−1  

= 1.095  × 10^6 ms−1

Hence the angular momentum of electron in the 3rd orbit is 1.095  × 10^6 ms−1