Understanding Electron Energy Levels in Hydrogen Atom
The total energy of an electron in the ground state of a hydrogen atom is -13.6 eV, which consists of both its kinetic energy and potential energy. The negative sign indicates that the electron is bound to the nucleus.

Kinetic Energy of Electron in First Excited State
- When an electron transitions from the ground state to the first excited state, it absorbs energy equal to the difference in energy levels. For hydrogen, this energy difference is 10.2 eV.
- The total energy of the electron in the first excited state can be calculated by adding this energy difference to the energy of the ground state: -13.6 eV + 10.2 eV = -3.4 eV.
- Since the total energy consists of both kinetic and potential energy, the kinetic energy of the electron in the first excited state can be calculated by subtracting the potential energy from the total energy. In this case, the potential energy at the first excited state is -3.4 eV, so the kinetic energy can be calculated as: -3.4 eV - (-13.6 eV) = 10.2 eV.
- Therefore, the kinetic energy of an electron in the first excited state of a hydrogen atom is 10.2 eV.
By understanding the energy levels and transitions of electrons in a hydrogen atom, we can calculate the kinetic energy of an electron in different states accurately.