In this case, there is a 2+ charge on the atom, so it is a cation.

Because this species has no charge, it is an atom in its elemental form.

Anions are named using the stem of the element name with the suffix -ide added.

This species has a 2− charge on it, so it is an anion.

Thus, Cl − is the chloride ion, and N 3− is the nitride ion. This is similar to how we named molecular compounds. In print, we use roman numerals in parentheses to represent the charge on the ion, so these two iron ions would be represented as the iron(II) cation and the iron(III) cation, respectively.įor a monatomic anion, use the stem of the element name and append the suffix -ide to it, and then add ion.

Thus, Fe 2+ is the iron two ion, while Fe 3+ is the iron three ion. If the element has more than one possible charge, the value of the charge comes after the element name and before the word ion. So Na + is the sodium ion Ca 2+ is the calcium ion. For a cation, simply use the name of the element and add the word ion (or if you want to be more specific, add cation) after the element’s name. An element symbol without a charge written next to it is assumed to be the uncharged atom. If the charge is a single positive or negative one, the number 1 is not written if the magnitude of the charge is greater than 1, then the number is written before the + or − sign. The magnitude of the charge is listed as a right superscript next to the symbol of the element. Note the convention for indicating an ion. Unfortunately, there is little understanding which two charges a metal atom may take, so it is best to just memorize the possible charges a particular element can have. Cobalt is another element that can form more than one possible charged ion (2+ and 3+), while lead can form 2+ or 4+ cations. For example, iron atoms can form 2+ cations or 3+ cations. A few elements, all metals, can form more than one possible charge. Third, there are some exceptions to the previous point. (In Chapter 9 “Chemical Bonds”, we will discuss why atoms form the charges they do.) Table 3.2 Monatomic Ions of Various Charges Ions formed by losing a single electron Thus, if you commit the information in Table 3.2 to memory, you will always know what charges most atoms form. When sodium atoms form ions, they always form a 1+ charge, never a 2+ or 3+ or even 1− charge. Second, most atoms form ions of a single characteristic charge. This is actually one of the chemical properties of metals and nonmetals: metals tend to form cations, while nonmetals tend to form anions. First, each element that forms cations is a metal, except for one (hydrogen), while each element that forms anions is a nonmetal. There are several things to notice about the ions in Table 3.2. Table 3.2 “Monatomic Ions of Various Charges” lists some common ions in terms of how many electrons they lose (making cations) or gain (making anions). When atoms gain or lose electrons, they usually gain or lose a characteristic number of electrons and so take on a characteristic overall charge. When they do, they become monatomic ions. Individual atoms can gain or lose electrons. Compounds formed from positive and negative ions are called ionic compounds.

Remember that ions are formed only when electrons move from one atom to another a proton never moves from one atom to another.

Species with overall positive charges are termed cations, while species with overall negative charges are called anions. Electrons can move from one atom to another when they do, species with overall electric charges are formed. They have the same number of electrons as protons, so the negative charges of the electrons is balanced by the positive charges of the protons. So far, we have discussed elements and compounds that are electrically neutral. Generate a proper name for an ionic compound.Construct a proper formula for an ionic compound.Learn the characteristic charges that ions have.

Iron iii sulfide charge