The ratio of the radii of the third orbit of He+ and Li2+ will be always 3:2.

The radius of first Bohr orbit of hydrogen atom is 0.529 A.

the basic formula for calculating the radius of nth orbit is Rn=0.529×(n^2/Z)angstrom where Z is the atomic number of the element.

Let rH be the radius first Bohr’s orbit of hydrogen atom. Thus, Be3+(n = 2) has same radius as that of the first Bohr’s orbit of H-atom.

From the formula for radius given by Bohr’s model of the Hydrogen atom, we can find the radius of the second orbit of the Helium ion. The atomic number of the Helium ion and the principal quantum number for the second orbit must be known. Therefore, the radius of the second orbit of the He+ ion is 1.058oA.

0.529 × 92​ Ao.

Answer. a) 1 will be the answer because both hydrogen and helium have only one orbit….

In hydrogen the energy of an orbital depends only on its principal quantum number, n (Figure 6.19); the 3s, 3p, and 3d subshells all have the same energy, for instance.

79×10−19J.

Logic: We know that energy of nth orbit, En = -K/n2 (for hydrogen atom), where K is a constant….Solution:

Bohr explained that electrons can be moved into different orbits with the addition of energy. When the energy is removed, the electrons return back to their ground state, emitting a corresponding amount of energy – a quantum of light, or photon.

The aufbau principle explains how electrons fill low energy orbitals (closer to the nucleus) before they fill higher energy ones. This means that the 4s orbital which will fill first, followed by all the 3d orbitals and then the 4p orbitals.