Question

Radius of the fourth atom is 0.85 nm.Calculate the velocity of the electron in this orbit (mass of electron 9.1x10^-31 kg)

Answer 1

(1). We know that, For Hydrogen atom Z=1

Also,

substituting this value in equation for velocity, we get

where, n = number of orbit = 4
h = planck's constant = 6.626 x 10-34Js
m = mass of an electron = 9.1 x 10-31kg
e = charge of an electron = 1.6 x 10-19C
k = Coulomb's law constant = 9 x 109Jm/C2.
Substituting these values in the above equation we get,
v = 5.45 x 106 ms-1.
(2). v = 500 m/s
Uncertainity in velocity = (500x0.02) / 100 = 0.1 m/s

(3). For K shell
n = 2
l = 0 , 1
m = -1,0,+1
s = -1/2, +1/2