Questions: Which of the following has the highest second ionization energy (IE2)? Select the correct answer below: Li K Na Cs

Transcript text: Which of the following has the highest second ionization energy $\left(\mathrm{IE}_{2}\right)$ ? Select the correct answer below: Li K Na Cs

Solution

Solution Steps

Step 1: Understanding Second Ionization Energy

The second ionization energy ($\mathrm{IE}_2$) is the energy required to remove the second electron from an atom after the first electron has already been removed. This energy is generally higher than the first ionization energy because it involves removing an electron from a positively charged ion.

Step 2: Analyzing the Elements

The elements given in the options are:

Li (Lithium)
K (Potassium)
Na (Sodium)
Cs (Cesium)

These elements are all alkali metals, which means they have a single electron in their outermost shell. After losing one electron, they form a stable noble gas configuration, making the second ionization energy significantly higher.

Step 3: Comparing Second Ionization Energies

For alkali metals, the second ionization energy increases as we move up the group in the periodic table. This is because the atomic size decreases, and the effective nuclear charge experienced by the remaining electrons increases, making it harder to remove the second electron.

Li: After losing one electron, it has a configuration similar to Helium, which is very stable.
Na: After losing one electron, it has a configuration similar to Neon.
K: After losing one electron, it has a configuration similar to Argon.
Cs: After losing one electron, it has a configuration similar to Xenon.

Since Lithium is at the top of the group, it will have the highest second ionization energy.