In the second row of the periodic table, \(\mathrm{Be}, \mathrm{N},\) and \(\mathrm{Ne}\) all have positive (unfavorable) electron affinities, whereas the other second-row elements have negative (favorable) electron affinities. Rationalize why Be, \(N,\) and Ne have unfavorable electron affinities.

Electron affinity is the amount of energy released or absorbed when an electron is added to a neutral atom, resulting in a negatively charged ion. In general, favorable electron affinities are associated with a release of energy by the atom when adding electrons.

The electronic configuration of an element is a representation of the distribution of electrons across its atomic orbitals. Elements in the same group (vertical column) in the periodic table have similar electronic configurations because they have the same number of electrons in their outermost shells. With this in mind, we can analyze the electronic configurations of Be, N, and Ne to explain their electron affinities.

Let's examine the electron configurations of Be, N, and Ne: 1. Be (Beryllium) - Atomic number = 4 Electronic configuration: \(1s^2\) \(2s^2\) 2. N (Nitrogen) - Atomic number = 7 Electronic configuration: \(1s^2\) \(2s^2\) \(2p^3\) 3. Ne (Neon) - Atomic number = 10 Electronic configuration: \(1s^2\) \(2s^2\) \(2p^6\)

Upon analyzing the electronic configurations of Be, N, and Ne, we can observe the following: 1. Be has a completely filled 2s orbital. Adding another electron would require promotion to the higher energy 2p orbital, which needs energy input, leading to an unfavorable electron affinity. 2. N has three unpaired electrons in its 2p orbitals. Adding another electron results in one of the 2p orbitals having two electrons with the same spin, which increases electrostatic repulsion. Therefore, energy must be provided to the system to allow this process to happen, making the electron affinity unfavorable. 3. Ne has a completely filled 2p orbital. Neon's electron configuration corresponds to a stable noble gas configuration, with completely filled s and p orbitals in the outer shell. To add an additional electron, it must be placed in a 3s orbital with higher energy, which requires energy input. Thus, Ne has an unfavorable electron affinity.

In summary, Be, N, and Ne have unfavorable electron affinities due to their specific electronic configurations, which require energy input to accommodate an extra electron. Be and Ne have completely filled outer orbitals, whereas N's electron affinity is affected by inducing an increase in electron-electron repulsion within its 2p orbitals.