Question
Which state of the triply ionized Be+++ has the same orbital radius as that of the ground state of hydrogen? Compare the energies of two states.
Solution
Radius of nth orbit is given by,
For hydrogen, Z = 1, n = 1 in ground state.
For Berylium, Z = 4, as orbital radius is same,
Hence n = 2.
Thus, second level of triply ionised Be+++ has same radius as the ground state of hydrogen.
Now energy of electron in nth orbit is given by,
Therefore, energy of ionized Be is greater than the energy of hydrogen in the ground state.
For hydrogen, Z = 1, n = 1 in ground state.
For Berylium, Z = 4, as orbital radius is same,
Hence n = 2.
Thus, second level of triply ionised Be+++ has same radius as the ground state of hydrogen.
Now energy of electron in nth orbit is given by,
Therefore, energy of ionized Be is greater than the energy of hydrogen in the ground state.