What is the physical significance of negative energy of electrons in an atom?

Hint: The energy of an electron that is produced in the orbit of an atom is negative. So, get a clear idea how it is formed, so that the physical significance of negative energy of electrons in an atom is known.

Complete step by step solution:
Generally, as it is known the negative energy of electrons in an atom is produced in the orbit. It is proved that the negative energy makes the electron bound to the nucleus. As the negative energy increases, the binding energy increases so that the electron bound more tightly to the nucleus. So, the system is more stable. To ionize the atom, external energy is required when the system is stable. The negative energy is more in the first orbit of the atom. So that the electrons bound more tightly to the nucleus in the first orbit. As the number of quantised orbits increases, the negative energy decreases. So, the binding energy decreases. Hence electrons are not bound to the nucleus as that of electrons in the first orbit. We can conclude that the electrons in the outermost orbit are least bound to the nucleus. This is the significance of the negative energy of electrons in an atom.

Note: Do not get confused between negative energy and positive energy. These terms do not really make sense. The potential energy is between the positive charge (nucleus) and the electron which makes it bound. As the charges are in opposite signs, it is called negative energy.