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**1. Homework Statement**

Hydrogen-like ions consist of one electron and a nucleus of a charge Ze (Z - the number of protons in the nucleus and e - the charge of an electron). The Bohr model of a hydrogen-like ion states that the single electron can exist only in certain allowed orbits around the nucleus. The radius of each Bohr orbit is: r=(a*n^2)/Z, where a = 0.0529 nm (Bohr'r radius of a hydrogen atom for n=1), n = 1, 2, 3, .... - the number of an allowed orbit (excited level), and Z - the number of protons in the nucleus.

Note: Express your answers in electron volts. Assume that potential energy PE = 0 at r = (infinity). For the hydrogen-like ion with Z = 3, that is Li+2 ion, determine the potential energy of the electron-nucleus system when the electron is in the

(a) first allowed orbit, n = 1;

(b) second allowed orbit, n = 2;

(c) when the electron has escaped from the atom, r = (infinity).

Determine the kinetic energy of the electron in the

(d) first allowed orbit, n = 1;

(e) second allowed orbit,

**2. Homework Equations**

r=(a*n^2)/Z

V=kQ/r

**3. The Attempt at a Solution**

I try plugging in the data into the equations, but I cannot even start a or b.