Ionic Bonds

Ionic Bonds

In this lesson, you will learn:

• why atoms form ionic bonds;

• what elements form ionic bonds;

• the properties of ionic compounds; and

• how to model ionic bonds.

​Some atoms share electrons in order to form a covalent bond.

Do you think there are other ways electrons can interact with other atoms to bond?

What might that look like?

The periodic table above highlights the three major groups of elements.

• The metals are located to the left of the periodic table.

• The nonmetals are located to the right of the periodic table.

• The metalloids follow a zigzag line between the metals and nonmetals.

You will need to be able to identify which category an element falls into for this lesson.

​Ionic Bonds

Ionic bonds form between atoms from opposite sides of the periodic table. A metal and a nonmetal will form an ionic bond. Examples of pairs that will form ionic bonds include:

• sodium and oxygen

• magnesium and chlorine

The reason the pairs form ionic bonds relates to how the atoms satisfy the octet rule.

Periodic Table

Multiple Choice

Which element is most likely to form an ionic bond with iodine?

• Oxygen

• Nitrogen

• Carbon

• Calcium

​Which element is most likely to form an ionic bond with iodine?


Ionic bonds form between atoms from opposite sides of the periodic table. A metal and a nonmetal will form an ionic bond.

​Ionic bonds form when electrons transfer from one atom to another. Whether the atom will give away or receive an electron depends on the number of valence electrons.

​Recall that atoms gain or lose electrons to satisfy the octet rule. An atom can either:

• gain electrons to total 8 valence electrons; or

• lose all of its valence electrons to empty the outer shell.

Whether an atom gains or loses electrons depends on its number of valence electrons.

​An atom that gains or loses electrons becomes an ion, or an atom with an electric charge. Electrons carry a negative charge, so:

• an atom that gains electrons becomes a negative ion; and

• an atom that loses electrons becomes a positive ion.

You indicate the charge of an ion by writing a superscript to the right and slightly above the symbol.

​Chemists usually write the number followed by the charge. For a charge of +1 or -1, simply write the charge without the number.

When forming ionic bonds:

• metal atoms give away electrons; and

• nonmetal atoms receive electrons.

​Sodium Chloride Ionic Bond Video

​This is similar to how the ionic bond holds charged ions together.

Modeling Ionic Bonds

Follow the steps below to use Lewis diagrams to model an ionic bond.

• Draw a Lewis structure of each element.

• Draw arrows to show the movement of the electrons. Add more of one atom at a time until all of the valence shells are stable.

• Draw the final structures of the ions.

​Example 1: Sodium and Chlorine

​Step 1

​Example 1: Sodium and Chlorine

​Step 2

​Example 1: Sodium and Chlorine

​Step 3

​Example 2: Calcium and Sulfur Video

​What will happen?!