Therefore, the attempt to reduce charging on the surface of wafers has been an attempt to provide electrons to produce the neutralization of the species within the ion beam. An ion with a positive charge is called a cation (you can remember the difference between cations and anions, negatively charged atoms, by noting that cation has a t which looks like a +). In such a state, the resulting charged atom has the electr… You can often determine the charge an ion normally has by the element’s position on the periodic table: The alkali metals (the IA elements) lose a single electron to form a cation with a 1+ charge. Each protein has an isoelectric point (pI), a pH at which the overall number of negative and positive charges is zero. The electrostatic attraction between the positives and negatives brings the particles together and creates an ionic compound, such as sodium chloride. At a pH >pI of a given protein, that protein becomes negatively charged (an anion), at the pH