What is an Ion?

What is an Ion?

An Ion

An ion is an atom that has gained or lost an electron and produces an atom with a charge either positive or negative

An Ion

• If an atom gains an electron it forms a negative ion because gaining an electron is gaining a negative charge.

• If an atom loses an electron it forms a positive ion because losing an electron is losing a negative charge.

• The charge is about the balance between protons (positive charge) and electrons (negative charge).

An Ion

As you can see here sodium (Na) loses an electron, giving it a full octet in its outer shell, and forms a positively charged atom or a positive ion also known as a cation.

An Ion

As you can see here chlorine (Cl) gains an electron, giving it a full octet in its outer shell, and forms a negatively charged atom or a negative ion also known as an anion.

An Ion

As you can see here calcium has 2 valence electrons. It would need to give up 2 electrons to form an octet in its outermost energy shell. When two electron are lost then a 2+ charged ion is formed.

An Ion

As you can see here nitrogen needs 3 valence electrons to form an octet. It would need to gain 3 electrons to form an octet in its outermost energy shell. When three electrons are gained then a 3- charged ion is formed.

You can use a chart like this to help you quickly find the charge of an ion.