Energy of an electron in the first Bohr orbit of hydrogen atom:
The energy of an electron in the first Bohr orbit of a hydrogen atom is calculated using the formula derived from Bohr's model of the hydrogen atom. In this model, the electron orbits the nucleus in circular paths at specific energy levels.

Explanation:
- The energy of an electron in the first Bohr orbit of a hydrogen atom is given by the formula: E = -13.6 eV (Z^2/n^2), where Z is the atomic number (1 for hydrogen) and n is the principal quantum number (1 for the first orbit).
- By substituting the values of Z and n into the formula, we get: E = -13.6 eV.
- This negative sign indicates that the electron is bound to the nucleus, and the energy required to remove the electron from the orbit is 13.6 eV.

Significance:
- The energy of an electron in the first Bohr orbit of a hydrogen atom is a crucial concept in understanding atomic structure and the behavior of electrons in atoms.
- This energy level represents the lowest possible energy state for an electron in a hydrogen atom, known as the ground state.

Conclusion:
- The energy of an electron in the first Bohr orbit of a hydrogen atom is -13.6 eV, indicating the stable and bound nature of the electron in this orbit. This value serves as a fundamental reference point in atomic physics and quantum mechanics.

Yes, it is -13.6 eV/ atom
because En = -13.6 z^2/n^2 and here in H atom z^2 is 1 and n^2 is also 1