Rank the elements Be, B, C, N, and O in order of increasing first ionization energy. Explain your reasoning.

Determine the position of each element (Be, B, C, N, and O) in the periodic table to understand their electronic configurations and how it relates to ionization energy. Be (Beryllium): Group 2, Period 2 B (Boron): Group 13, Period 2 C (Carbon): Group 14, Period 2 N (Nitrogen): Group 15, Period 2 O (Oxygen): Group 16, Period 2 We can see that all these elements belong to Period 2, meaning they are in the same row and have their outermost electrons in the same (2nd) energy level, but they belong to different groups.

Write the electronic configurations of the elements by considering their positions in the periodic table, which will help us assess their shielding and attraction to the nucleus. Be: 1s² 2s² B: 1s² 2s² 2p¹ C: 1s² 2s² 2p² N: 1s² 2s² 2p³ O: 1s² 2s² 2p⁴

Compare the elements based on atomic size, nuclear charge, and electron shielding: - Atomic size: All the elements are in the same period, so going from left to right, the atomic size generally decreases. Thus, Be has the largest atomic size, and O has the smallest atomic size. - Nuclear charge: Going from left to right, the nuclear charge increases due to an increase in the number of protons. Thus, Be has the smallest nuclear charge and O has the largest nuclear charge. - Electron shielding: In these elements, the outermost electrons are in the same energy level, so they have roughly the same shielding effect.

Consider the factors affecting ionization energy to rank the elements: Be has the largest atomic size and the lowest nuclear charge, making it the easiest to remove an electron, indicating the lowest ionization energy. On the other hand, O has the smallest atomic size and the highest nuclear charge, making it the hardest to remove an electron, indicating the highest ionization energy. However, N has a half-filled 2p subshell, which provides extra stability and makes it harder to ionize than both C and O. This stability means N will have a higher ionization energy than C and O. So, taking this into account, we can now rank the elements as follows: Be < B < C < O < N Therefore, the order of the elements in terms of increasing first ionization energy is Be, B, C, O, and N.