The energy required to remove an electron from a gaseous atom is called

kinetic energy

free energy

A ionization energy

B lattice energy

C activation energy

The correct answer and explanation is:

Correct Answer: A) Ionization energy

The energy required to remove an electron from a gaseous atom is called ionization energy. This is a fundamental concept in atomic physics and chemistry. It refers to the minimum amount of energy needed to completely remove the outermost (or highest energy) electron from a neutral atom in its gaseous state, resulting in the formation of a positively charged ion.

Ionization energy is measured in units such as kilojoules per mole (kJ/mol) or electron volts (eV). Each element has a unique ionization energy depending on factors such as atomic size, nuclear charge, and electron shielding. Atoms with a small radius and a high positive charge in the nucleus tend to have higher ionization energies because the electrons are held more tightly.

Ionization energy increases across a period in the periodic table from left to right. This is because atoms become smaller and their electrons are more strongly attracted to the nucleus due to increased nuclear charge. Conversely, ionization energy decreases down a group. As atoms get larger, their outer electrons are farther from the nucleus and experience more shielding from inner electrons, making them easier to remove.

The other answer choices do not fit this definition. Lattice energy refers to the energy released when ions form an ionic solid from the gaseous state. Activation energy is the energy needed to start a chemical reaction. Free energy, often called Gibbs free energy, is related to the energy available to do work in a thermodynamic system and is not specific to removing electrons. Kinetic energy describes the energy of motion and is unrelated to the electron-removal process.

Therefore, the correct and most precise term for the energy needed to remove an electron from a gaseous atom is ionization energy.