Final answer:
The definition of ionization energy as the energy required to remove the most loosely bound electron from an isolated gaseous atom or ion is true. Ionization energy is positive and is measured in kJ/mol or eV.
Step-by-step explanation:
The statement that ionization energy is defined as the energy required to remove the most loosely bound electron from an isolated gaseous atom or ion is true. Ionization energy, often denoted by IE, represents the minimum amount of energy necessary to dislodge an electron from the outermost shell of an atom in its gaseous state and thus form a cation.
This process is depicted by the reaction X(g) → X+(g) + e− where X is the element and e− is the electron being removed.
The first ionization energy, noted as IE1, is specifically the energy required to remove the first electron, forming a cation with a +1 charge. Subsequent electrons can also be removed with increasing amounts of energy, giving rise to terms such as second ionization energy (IE2), and so forth for successive electrons.
The ionization energy is an intrinsic property of an element and is always positive, reflecting the input of energy needed for this endothermic process. Typical units for measuring ionization energy are kilojoules per mole (kJ/mol) or electron volts (eV).