Positive Monoatomic Ions

1. Positive Monoatomic Ions Positive monoatomic ions are metals. The ions are formed when the metal atoms lose electrons. Metals can be divided into three different classes in analyzing the metal ions.

2. 1. Metals of groups Ia, IIa, and IIIa usually form positive ions based on the Octet rule. Octet Rule – Atoms will gain or lose electrons to reach an electron configuration equivalent to the nearest noble gas. The goal involves a total of eight valence electrons since all noble gases have eight valence electrons except of helium which has only two. Example: Lithium is a group 1a metal whose nearest noble gas is helium. To obtain the electron configuration of helium, lithium must lose one electron. Since electrons have a negative charge, loosing one electron changes the neutral lithium atom to a positive ion with a +1 charge (Li +).

3. 2. Group IVa Metals The group IVa metals are multivalent, either 2+ or 4+ Tin can be Sn 2+ or Sn 4+. Lead can be Pb 2+ or Pb 4+.

4. 3. Transitional Metals Charges for the ions of transitional metals cannot be easily predicted. A. Some transitional metals are essentially monovalent. For example, Zinc is almost always Zn 2+. Silver is almost always Ag +. Nickel is almost always Ni 2+. B. Many transitional metals are multivalent. For example, Copper can be Cu + or Cu 2+. Iron can be Fe 2+ or Fe 3+. The student will need to memorize the above transitional metal charges.

5. Naming Positive Monoatomic Ions The name of positive, monoatomic ions is the same as the name of the element. For example, Zn 2+ is called zinc or the zinc ion. For multivalent metals, a roman numeral is added to the element name to designate the charge on the specified ion. For example, Fe 2+ is iron (II) or the iron (II) ion. Fe 3+ is iron (III) or the iron (III) ion.