Question

a single electron orbits a stationary nucleus (z=5) What is the energy required to excite electron from third to fourth Bohr orbit ?

Answer 1

The ground ionisation energy of hydrogen is :

13.6eV

En = - 13.6 × Z²/n²

E = E₄ - E₃

E = - 13.6 × 5² {1/4² - 1/3²)

E = - 13.6 × 25 × {-7/144}

= 16.53eV

Answer 2

Answer:

16.52 eV is the energy required to excite electron from third to fourth Bohr orbit.

Explanation:

Energy of the nth Bohr orbit is given by:

$E_n=-13.6\frac{Z^2}{n^2} eV$

n = Principle quantum number

Z = Atomic mass

Energy associated with third Bohr orbit:

$E_3=-13.6\frac{(5)^2}{(3)^2} eV=-37.77 eV$

Energy associated with forth Bohr orbit:

$E_4=-13.6\frac{(5)^2}{(4)^2} eV=-21.25 eV$

Energy required to excite electron from third to fourth Bohr orbit:

$E=E_4-E_3=-21.25 eV-(-37.77 eV)=16.52 eV$