Rank the following elements by ionization energy. Rank from highest to lowest ionization energy. To rank items as equivalent, overlap them. Kr Ne Xe Highest Lowest
The Correct Answer and Explanation is :
The correct ranking of the given elements by ionization energy, from highest to lowest, is:
Ne > Kr > Xe
Explanation:
Ionization energy is the energy required to remove the outermost electron from an atom in its gaseous state. Several factors influence ionization energy, including the size of the atom, the effective nuclear charge, and the electron configuration. Let’s examine these factors for the noble gases Ne (Neon), Kr (Krypton), and Xe (Xenon):
- Atomic Size:
- Neon has the smallest atomic radius among the three elements, as it is in the second period of the periodic table. Krypton and xenon are in the fourth and fifth periods, respectively, and their larger atomic radii result in a weaker attraction between the nucleus and the outermost electron.
- Smaller atoms (like neon) have higher ionization energies because the electrons are closer to the nucleus and are held more tightly.
- Effective Nuclear Charge:
- The effective nuclear charge (the net positive charge experienced by valence electrons) is higher in smaller atoms like neon. While krypton and xenon have higher numbers of protons, their outermost electrons experience significant shielding from inner electron shells, reducing the effective nuclear charge.
- Electron Configuration:
- All three elements are noble gases with a full outer shell, making them stable. However, due to the stronger attraction of electrons in smaller atoms (like neon), it is harder to remove an electron compared to larger atoms.
- Period Trend:
- Ionization energy decreases as you move down a group in the periodic table because the outermost electrons are farther from the nucleus and are less tightly bound.
Conclusion:
Neon, being the smallest and least shielded, has the highest ionization energy. Krypton, being intermediate, has a lower ionization energy than neon but higher than xenon. Xenon, the largest and most shielded, has the lowest ionization energy.