Ions and the Periodic Table

The periodic table can be helpful when you want to know what type of ion is formed by a given element.

Elements have the ability to gain and lose electrons. As a result, they can have positive and negative charges. An ion is an element with a positive or negative charge. A cation is an ion with a positive charge and an anion is an ion with a negative charge. The periodic table can helpful you figure out the charge of an element based on the location within the periodic table. For example, the metals in group 2A create a 2 + cation and elements in group 7A can create 1- anions.



A very helpful fact that will help as you try to figure out what type of ion will be created is that …..

Metals will always form positive ions and nonmetals will create negative ions.

metals create cations nonmetals creat anions
periodic table and ions

The group 1a metals all form 1+ ions

The group 2A metals all form 2+ ions

The group 3A metals all form 3+ ions

So for groups 1-3 the charges of the cations will be the same as the group number.

In contrast,most of the transition metals form cations with various positive charges. For these elements there is no easy way to predict the charge of the cation that will be formed.

All group 7A nonmetals form 1- ions by gaining 1 electron.

All nonmetals in group 6A gain two electrons and create 2- ions.

In group 5A the nonmetals and arsenic have a 3- charge. 

Group 4A has carbon so you may see it labeled -4 and + 4 for ions.

The noble gasses have a zero charge.


In summary, metals always form positive ions called cations and nonmetals form negative ions called anions and the periodic table can be a helpful tool to be used in order to figure out what type of ion an element will form.