| Ion table | Periodic table group number | | | |
| 1 | 2 | | | | | | | |
| | | | | | | O2– | | |
| Na+ | Mg2+ | Al3+ | | | S2– | Cl– | |
| K+ | Ca2+ | | | | | Br– | |
| | | | | | | I– | |
| | Ba2+ | | Pb2+ | | | | |
The ions above are arranged in the order of appearance of these elements in the groups in the periodic table.
The
cations above are the only monatomic ions formed by these elements.
The
names of the cations are the
element name followed by
ion.
Ca2+ is calcium ion and Na+ is sodium ion.
Note for the Group 1, 2 and
metal cations ions that the magnitude of the positive charge is equal to the
last digit of the Group number.
The
anions in the table are the only monatomic ions formed by these elements.
Name these anions using the
first part of the element name plus
-ide.
Cl– chloride Br– bromide I– iodide
O2– oxide S2– sulfide
Note that the magnitude of the
negative charge for the monatomic anions is equal to the
Group number -
Transition metals also form
monatomic cations as shown in the examples below.
Transition metals may form more than one ion, and, if so, these are given different names.
Iron forms Fe2+ and Fe3+. These are referred to as the iron(II) and iron(III) ions.
Copper forms Cu2+ (copper ion).
Zinc forms Zn2+ (zinc ion).
Silver forms Ag+ (silver ion).