What Is Ion?

An ion is a molecule that has a net electrical charge. Since the charge of the electron (considered negative by convention) is equal and opposite to that of the proton (considered positive by convention), the net charge of an ion is non-zero due to its total number of electrons being unequal to its total number of protons.

A cation is a positively charged ion, with fewer electrons than protons, while an anion is negatively charged, with more electrons than protons. Because of their opposite electric charges, cations and anions attract each other and readily form ionic compounds.

When writing the chemical formula for an ion, its net charge is written in superscript immediately after the chemical structure for the molecule/atom. The net charge is written with the magnitude before the sign; that is, a doubly charged cation is indicated as 2+ instead of +2. However, the magnitude of the charge is omitted for singly charged ions.

Here are some example ions:

• H⁺: Hydrogen cation or hydrogen ion is the hydrogen atom without its only one electron.
• Li⁺: Lithium cation
• Na⁺: Sodium cation
• Ag⁺: Silver cation
• Ca²⁺: Calcium cation
• Fe²⁺: Iron(II) cation
• Fe³⁺: Iron(III) cation
• Al³⁺: Alumium cation
• Sn⁴⁺: Tin(IV) cation
• NH₄⁺: Ammonium cation.
• F^-: Fluoride anion
• Cl^-: Chloride anion
• OH^-: Hydroxide anion.
• NO₃^-: Nitrate anion.
• NO₂^-: Nitrite anion.
• O^2-: Oxide anion.
• CO₃^2-: Carbonate anion.
• N^3-: Nitride anion

 

⇒ What Are Valence Electrons

⇐ Skeletal Formula Notations

⇑ Introduction to Molecules

⇑⇑ Molecule FAQ