Calculate an atom or ion's net charge from protons and electrons, or find electrons gained or lost from charge in C or e.
Net Charge Formula
The following formula is used to calculate a net charge.
- Where Q is the net charge (C)
- n is the number of electrons transferred (use + for electrons lost, − for electrons gained)
- e is the magnitude of the elementary charge, |e| = 1.602176634×10^-19 C (an electron has charge −|e|)
To calculate a net charge, multiply the number of electrons transferred by the elementary charge magnitude, then apply a negative sign if electrons were gained and a positive sign if electrons were lost.
Net Charge Definition
What is a net charge? Net charge is the sum of an object’s positive and negative charges; equal totals give zero net charge. For an atom or ion, Q = (protons − electrons)e. Electron-transfer calculations here assume an initially neutral object.
Example Problem
How to calculate net charge?
- First, determine the charge of one electron.
The magnitude of the elementary charge is approximately 1.6*10^-19 C (an electron carries -1.6*10^-19 C), where C is the unit symbol for coulombs.
- Next, determine the number of electrons gained or lost.
For this problem, the atom has gained 2 electrons.
- Finally, calculate the net charge.
Using the formula above, since electrons were gained the charge is negative: Q = -(1.6*10^-19 C) * 2 = -3.2*10^-19 C.
