counterion
nounUK /ˈkaʊntəraɪən/
US /ˈkaʊntəraɪən/
A counterion is a tiny charged particle that stays close to another particle with the opposite charge.
In salt water, the sodium ions act as counterions to the chloride ions.
RELATED WORDS
OTHER MEANINGS
2. An ion that neutralizes the charge of a colloidal particle in a solution.
Adding salt increases the counterion concentration and can make the colloid clump together.
3. A small ion that balances the charge of a large charged molecule such as a protein or polymer.
The protein carries a negative charge, so small counterions gather around it.
4. An ion of opposite charge that pairs with a surfactant molecule in a micelle.
The counterion helps keep the soap molecules dissolved in water.