Cathode (source code)
= Cathode
{wiki}
The <cathode> is the <electrode> at which the net <electrode> <chemical reaction> is <reduction>: the reacting <chemical species> gains <Electrons>. This definition is independent of terminal sign. During <Daniell cell> discharge, $\mathrm{Cu}^{2+}$ <cations> accept <Electrons> arriving at the <copper> <cathode> and become neutral <copper>. The <cathode> is then the positive terminal. In an externally driven <electrolytic cell>, the source's negative terminal supplies <Electrons> to the negative <cathode>. See https://doi.org/10.1515/pac-2018-0109[Pingarrón et al., §3.4: cathode] and <Daniell cell>.
An <ion> carrying <electric current> need not undergo <reduction> at the <cathode>. For example, in the ideal <Daniell cell> charge-balance picture, <potassium> <cations> arriving from a <salt bridge> remain dissolved while $\mathrm{Cu}^{2+}$ <cations> are consumed. Follow the <half-reaction> to identify the reacting species; follow <electric charge conservation> to account for the other moving <ions>.
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