DENDROLOGY

Detailed explanation-1: -When an electron temporarily occupies an energy state greater than its ground state, it is in an excited state. An electron can become excited if it is given extra energy, such as if it absorbs a photon, or packet of light, or collides with a nearby atom or particle.

Detailed explanation-2: -When an electron in an atom has absorbed energy it is said to be in an excited state. An excited atom is unstable and tends to rearrange itself to return to its lowest energy state. When this happens, the electrons lose some or all of the excess energy by emitting light.

Detailed explanation-3: -Ionization of Atoms When an atom gains an electron, energy is usually released. This energy is called the electron affinity of that atomic species. Atoms that have a large electron affinity are more likely to gain an electron and form negative ions. Loss of an electron from an atom requires energy input.