The energy of the electron in the ground state of a hydrogen atom is

  • A. minus 13.6 eV
  • B. plus 13.6 eV
  • C. zero
  • D. minus 3.4 eV

Explanation

The negative sign means the electron is bound, and 13.6 eV is therefore the energy needed to remove it completely, which is the ionisation energy of hydrogen. The n equals 2 level lies at minus 3.4 eV, which is minus 13.6 divided by 4, since the energy varies as one over n squared. Energy is defined as zero for a free electron at rest.

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