Question 454: Atoms & Nuclei

Question

When a hydrogen atom is raised from the ground state to the excited state

Accepted Answer

In the (simplified) Bohr model of the hydrogen atom:
The
total energy
$E_n$ in the $n^	ext{th}$ orbit is
$     E_n = -\frac{13.6\,	ext{eV}}{n^2}.   $
The
kinetic energy
of the electron is
$     K_n = -E_n = \frac{13.6\,	ext{eV}}{n^2}.   $
The
potential energy
of the electron is
$     U_n = 2E_n = -\frac{27.2\,	ext{eV}}{n^2}.   $
When the atom is excited from $n=1$ (ground state) to $n>1$ (an excited state):
$E_n$ becomes
less negative
(it increases toward 0).
$K_n$
decreases
, because $K_n = 13.6\,	ext{eV}/n^2$ gets smaller for larger $n$.
$U_n$ becomes
less negative
, which means $U_n$ is effectively
increasing
(going from a larger negative value to a smaller negative value).
Therefore, when a hydrogen atom is raised from the ground state to an excited state,
the potential energy increases
(less negative),
the kinetic energy decreases
.
Hence the correct option is:
$ \boxed{	ext{(A) potential energy increases and K.E. decreases.}} $

Answer

potential energy increases and K.E. decreases.

Answer

potential energy decreases and K.E. increases.

Answer

both K.E. and potential energy will increase.

Answer

both K.E. and potential energy decreases.

Atoms & Nuclei

When a hydrogen atom is raised from the ground state to the excited state

Choose the correct answer: