Which atom or ion in the following pairs would you expect to be larger? (c) O-or O2-

검증된 단계별 안내

Identify the species involved: O^- and O^{2-}.

Understand that both species are anions of oxygen, meaning they have gained electrons.

Recall that the size of an ion is influenced by the number of electrons and the effective nuclear charge.

Note that O^- has gained one electron, while O^{2-} has gained two electrons.

Recognize that with more electrons, O^{2-} experiences greater electron-electron repulsion, leading to a larger size compared to O^-.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Atomic Radius

Atomic radius refers to the size of an atom, typically measured from the nucleus to the outermost electron shell. As you move down a group in the periodic table, atomic radius increases due to the addition of electron shells. Conversely, across a period, atomic radius generally decreases due to increased nuclear charge, which pulls electrons closer to the nucleus.

Ionic Radius

Ionic radius is the measure of an atom's ion in a crystal lattice. Cations (positively charged ions) are smaller than their neutral atoms because they lose one or more electrons, reducing electron-electron repulsion and allowing the remaining electrons to be pulled closer to the nucleus. Anions (negatively charged ions), like O2-, are larger than their neutral atoms due to the addition of electrons, which increases electron-electron repulsion.

Electron Configuration and Stability

Electron configuration describes the distribution of electrons in an atom's orbitals. For oxygen, the neutral atom has six electrons, while O2- has eight, achieving a more stable electron configuration similar to that of noble gases. This added stability in anions often results in a larger ionic radius compared to their neutral counterparts, as the additional electrons increase repulsion among them.