negativecharge

Negative charge is a property of matter that arises from an excess of electrons relative to protons, resulting in a net electric charge with a negative sign. In physics and chemistry, the sign convention assigns negative charge to electrons and positive charge to protons; the total charge Q is the sum of all elementary charges. The elementary charge magnitude is e ≈ 1.602176634×10^−19 C, so a single electron carries −e.

Most atoms are neutral when the number of electrons equals the number of protons; negative charge appears in ions such as chloride Cl− or oxide O^2−, in subatomic particles like electrons, and in certain molecules that have excess electrons. In plasmas or conducting materials, negative charges can move and accumulate on surfaces or within the bulk.

Negative charges generate and respond to electric fields according to Coulomb's law: like charges repel, opposite charges attract. They experience force in electric fields, and their distribution determines potential and capacitance in circuits. In conductors, excess electrons reside near surfaces and can flow when a potential difference is applied. Measurements are typically in coulombs or multiples of the elementary charge.

Negative charge can be introduced by gaining electrons (reduction), contact electrification, photoionization, or chemical reactions; it can be removed by oxidation, electron transfer to a neutral or positive species, or grounding. Discharge neutralizes excess negative charge by allowing electrons to flow to the ground or to positive charges.