Why for any material, the number of ion transfers plus electron transfers equal 1?
I do not understand the question, but when 1 electron is removed from an atom, the atom becomes an ion that has a net positive charge of the same magnitude. Remove 2 electrons, and the ion has a net positive charge of twice the magnitude of the electron charge. Protons and electrons have opposite charges of equal magnitude.
Nature as far as we know it, or at least in our part of the universe, tends to be electrically neutral. Negative charges (electrons) are never far from the corresponding positive charges, and they tend to get closer whenever the opportunity arises.
Actually, I'm not too sure of what that sentence means either... Just for fun, I picked up a book, "Fundamentals of Ceramics" to read, which is by Micheal Barsoum, and that sentence is on pg 213...
Separate names with a comma.