An ion is an atom or molecule with a net electrical charge, occurring when the number of electrons is unequal to the number of protons—positively charged cations (like K⁺) have fewer electrons, while negatively charged anions (like Cl⁻) have more. The term "ion" was coined by Michael Faraday in 1834 (with a suggestion from William Whewell), who also named the anode, cathode, anion, and cation based on how these particles move toward oppositely charged electrodes. In 1884, Svante Arrhenius explained that solid salts dissociate into paired charged particles when dissolved—a breakthrough that earned him the 1903 Nobel Prize in Chemistry. Ions can form through physical collisions in gases, chemical reactions like dissolving salt in water, or passing an electric current through a solution. While ions in a gas-like state are highly reactive, they become stable when solvated by solvents such as water, which is why they are commonly found in environments like seawater.