Which of the following has the smallest second ionization energy?

Which of the following has the smallest second ionization energy?

• A. C
• B. Na
• C. O
• D. Ca

Answer: (D)

Second ionization energy refers to the energy required to remove a second electron from a neutral atom after the first electron has already been removed. This process is influenced by the electron configuration and the resulting effective nuclear charge acting on the remaining electrons. Calcium, which is in Group 2 of the periodic table, has a relatively low first ionization energy due to its larger atomic size and the presence of two electrons in its outer shell. When the first electron is removed, calcium forms a +1 cation (Ca⁺), which has a stable electron configuration. The removal of a second electron (to form Ca²⁺) requires overcoming both the attraction between the positively charged Ca⁺ ion and the remaining electrons and the repulsion effects within the remaining electron cloud. Due to the fact that removing an electron from a positively charged ion is less energetically favorable than from a neutral atom, calcium's second ionization energy will be lower than that of the other elements listed. In comparison, the other elements such as carbon, sodium, and oxygen show differences in their electron configurations and group placements. Carbon, for example, will require additional energy to remove a second electron after it has already lost one, due to its group location and effective nuclear

Second ionization energy refers to the energy required to remove a second electron from a neutral atom after the first electron has already been removed. This process is influenced by the electron configuration and the resulting effective nuclear charge acting on the remaining electrons.

Calcium, which is in Group 2 of the periodic table, has a relatively low first ionization energy due to its larger atomic size and the presence of two electrons in its outer shell. When the first electron is removed, calcium forms a +1 cation (Ca⁺), which has a stable electron configuration. The removal of a second electron (to form Ca²⁺) requires overcoming both the attraction between the positively charged Ca⁺ ion and the remaining electrons and the repulsion effects within the remaining electron cloud.

Due to the fact that removing an electron from a positively charged ion is less energetically favorable than from a neutral atom, calcium's second ionization energy will be lower than that of the other elements listed.

In comparison, the other elements such as carbon, sodium, and oxygen show differences in their electron configurations and group placements. Carbon, for example, will require additional energy to remove a second electron after it has already lost one, due to its group location and effective nuclear