Answer:
Hydrogen is the smallest chemical element. It has one proton and one electron, making it neutral. However, the ions of hydrogen atom are charged species. Thus, the key difference between hydrogen atom and hydrogen ion is that the hydrogen atom is neutral whereas hydrogen ion carries a charge.
Answer:
Since electrons cannot have the same set of quantum numbers, a maximum of two can be in the n = 1 level, and a third electron must reside in the higher-energy n = 2 level. If there are two electrons in the n = 1 level, their spins must be in opposite directions.
