Final answer:
The energy required to remove an electron from the first energy level of a lithium ion is termed ionization energy, and it is a measure of how strongly electrons are held within an atom, leading to the formation of a more positively charged ion.
Step-by-step explanation:
The energy required to remove an electron from the first energy level of a lithium ion is known as ionization energy. This is because energy must be supplied to overcome the attraction between the negative electron and the positive nucleus, resulting in the formation of a cation. The lithium ion already has a positive charge, and removing an additional electron from it would require supplying the atom with additional energy. The process in which an electron is removed and the atom becomes more positively charged is represented by the reaction:
X(g) → X+1(g) + e¯
The ionization energy is always positive and is measured in either kilojoules per mole (kJ/mol) or electron volts (eV). When querying about a lithium ion, we are considering the energy required to remove an electron from a cation, which would likely be higher than removing one from a neutral atom.