What is ionization energy?
ChemistryClass 10CBSEAnswered 28 May 2026
Answer
Ionization energy is the minimum energy required to remove the outermost electron from a neutral gaseous atom in its ground state, measured in kJ/mol.
Periodic Trend:
| Direction | Trend | Reason |
|---|---|---|
| Across a period (left → right) | Increases | Nuclear charge increases |
| Down a group | Decreases | Electrons farther from nucleus |
Ionization energy is the energy needed to remove an electron from a gaseous atom, increasing across periods and decreasing down groups.