Question
Why the energy of electron in an atom is negative?
Solution
The expression for the energy of hydrogen electron is
This means that when the electron is at infinite distance from the nucleus, there is no electrostatic interaction between the two. At this point, the energy of the electron is taken as zero. As the electron moves closer to the nucleus, it does some work due to electrostatic attraction. In doing so, electron spends some of its energy. Therefore, energy of an electron becomes less than zero i.e. negative. That is why energy of electron in an atom is negative.
This means that when the electron is at infinite distance from the nucleus, there is no electrostatic interaction between the two. At this point, the energy of the electron is taken as zero. As the electron moves closer to the nucleus, it does some work due to electrostatic attraction. In doing so, electron spends some of its energy. Therefore, energy of an electron becomes less than zero i.e. negative. That is why energy of electron in an atom is negative.
