The electrons in the outermost shell of an atom are called valence electrons. These electrons play a crucial role in determining how an atom interacts and bonds with other atoms.
Valence electrons are significant because they are the ones involved in chemical reactions. The number of valence electrons can influence the chemical properties of an element, including its reactivity, the types of bonds it can form, and its overall stability.
For instance, elements with a full outer shell, like the noble gases, are typically more stable and less reactive. In contrast, elements with fewer valence electrons will seek to either gain or lose electrons to achieve a full outer shell, which leads to chemical reactions.