Nepedia
Back to Discover
Fluent Reader
⚛️

Ion

physical science Maturity 9-11 Next article →

An ion is a tiny part of our world that carries an electric charge. Most atoms are neutral, meaning they have no charge at all. This happens because they have the same number of protons and electrons. Protons have a positive charge, while electrons have a negative charge. When these numbers are not equal, the atom becomes an ion.

Ions
Ions

This change is very important for how the universe works. Ions are found everywhere, from the bright light of the Sun to the salt in our oceans. They even help give gemstones their beautiful colors.

Ionic bonding
Ionic bonding

There are two main ways an ion can be charged. A cation is a positively charged ion. It happens when an atom has fewer electrons than protons. An anion is a negatively charged ion. This occurs when an atom has more electrons than protons.

Ions notation
Ions notation

Because they have opposite charges, cations and anions pull toward each other. This pull is called electrostatic force. This force is what allows them to join together to form ionic compounds, like the salt we use on food. When ions are in a liquid, they can also form stable groups by interacting with the liquid around them.

Scientists have been studying these moving particles for a long time. The word "ion" comes from a Greek word that means "to go." This is because ions move through liquids. In 1834, a scientist named Michael Faraday used this term. He noticed that substances moved through a solution during an electric current. A friend named William Whewell helped him by suggesting the names cation and anion. Cations move toward the negative side, and anions move toward the positive side. Later, in 1884, Svante Arrhenius explained how salts break into these ions when they dissolve in water. He later won the Nobel Prize in Chemistry for this work.

Ions come in different sizes and shapes. A monatomic ion is made of just one single atom. A polyatomic ion is a group of two or more atoms acting together.

Ions notation2
Ions notation2

Interestingly, the size of an ion changes based on its charge. Anions are usually larger than the original atom because their extra electrons push outward. Cations are usually smaller than the original atom. For example, a hydrogen cation is just a single proton, which is very tiny.

Ions notation
Ions notation

Scientists use small signs to show these charges. They write a plus or minus sign next to the name. If the charge is stronger, they add a number, like 2+ or 2-.

We use the power of ions in many modern tools. Scientists use them in machines called mass spectrometers and particle accelerators. They are even used in household smoke detectors to keep homes safe.

Ion chamber operation
Ion chamber operation

In nature, ions help living things work. They help control how cells send signals and how they use energy. If the balance of ions in a cell is broken, the cell can die. This is how some medicines, called biocides, work to stop harmful things like fungi. From the deep ocean to the machines in our homes, ions are always busy at work.

507 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (7)
File:Ionic bonding.svg
Ionic bonding.svg
File:Ions.svg
Ions.svg
File:Ion chamber operation.gif
Ion chamber operation.gif
File:Electron avalanche.gif
Electron avalanche.gif
File:Ions notation.svg
Ions notation.svg
File:Ions notation2.svg
Ions notation2.svg
File:Nitrate-ion-elpot.png
Nitrate-ion-elpot.png
More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.