Which property of an atom describes the amount of energy required to remove an electron from a gaseous atom in its ground state?

• A. Atomic radius
• B. Ionization energy
• C. Electron affinity
• D. Electronegativity

Answer: (B)

Verified step by step guidance

1. Understand that the question is asking about the energy needed to remove an electron from a gaseous atom in its ground state.
2. Recall the definitions of the given properties: Atomic radius refers to the size of the atom; Electron affinity is the energy change when an atom gains an electron; Electronegativity is the tendency of an atom to attract electrons in a chemical bond.
3. Identify that the property related to removing an electron (which means overcoming the attraction between the nucleus and the electron) is called Ionization energy.
4. Ionization energy is defined as the minimum energy required to remove one mole of electrons from one mole of gaseous atoms or ions in their ground state, expressed as \(\mathrm{X(g) \rightarrow X^{+}(g) + e^{-}}\).
5. Therefore, the correct property describing the energy needed to remove an electron from a gaseous atom in its ground state is Ionization energy.