"Helium is different than other elements with two valence electrons, such as beryllium, because it has a full outer shell of electrons. Helium's electron configuration is 1s², which means its first energy level (or shell) is completely filled with two electrons. This makes helium extremely stable and unreactive with other elements, unlike beryllium, which has two valence electrons in an incomplete outer shell and is more reactive.
In contrast, neon (Ne) also has a full outer shell of electrons, but it has a larger number of electrons in total than helium. Neon's electron configuration is 1s² 2s² 2p⁶, meaning its second energy level is also filled, providing additional stability. Therefore, helium is more similar to neon in terms of its electron configuration and chemical behavior than it is to beryllium, which has a partially-filled outer shell and is more reactive." (ChatGPT, 2023)