Final answer:
The delocalized negative charge is distributed over two or more atoms, often outlined by Lewis structures and guided by formal charge calculations. Without a provided structure, it is not possible to determine which specific atoms the charge is delocalized onto, but generally, it is on the more electronegative elements.
Step-by-step explanation:
The negative charge in a molecule is said to be delocalized when it can be distributed over two or more atoms. When evaluating which atom the negative charge is delocalized onto, we consider the Lewis structure and the electronegativity of the atoms involved. Formal charge calculations guide us to the most stable structure. For a molecule like the one with four hydrogens bonded to a central boron and surrounded by square brackets indicating a negative charge, we look at each atom's formal charge; the boron atom has a -1 formal charge. Guideline 4 states that the structure with the negative formal charges on the more electronegative atoms is preferable. However, in cases where the element is less electronegative, like boron, we still observe the negative charge on it if the molecule is drawn as such.
Delocalization of the negative charge can also be reasoned out with the concept that negative formal charges should be on the more electronegative element. Unfortunately, without the specific structure to refer to, we cannot confirm which numbered atoms would have the delocalized negative charge. In a polar bond, such as between hydrogen and fluorine, the negative charge is represented with a lowercase Greek letter delta (δ-) next to the more electronegative atom (fluorine in this case).