When an atom loses one or more electrons, the number of protons in the nucleus remains the same, while the number of electrons decreases. As a result, the attraction between the positively charged nucleus and the negatively charged electrons increases, causing the overall size of the ion to shrink. For example, when the calcium atom (Ca) loses two electrons to form a calcium ion (Ca2+), the remaining electrons are pulled closer to the nucleus, resulting in a smaller cation. In general, the more positive the charge on an ion, the smaller its size will be. Therefore, cations are typically smaller than their parent atoms or neutral molecules.