The energy change that accompanies the addition of an electron to an isolated gaseous atom is

The energy change that occurs when an electron is added to an isolated gaseous atom is called "electron affinity." This process involves adding an electron to a neutral atom, which then becomes a negatively charged ion. Electron affinity is a measure of how much energy is released or absorbed when this happens. If energy is released, the electron affinity is negative, meaning the atom is more likely to attract electrons. If energy is absorbed, the electron affinity is positive, meaning the atom is less likely to attract electrons. The electron affinity is related to the ionization energy, which is the energy required to remove an electron from an atom.