How Do You Find the Number of Electrons in an Element?
To find the number of electrons an element has, locate it on the periodic table of elements, find the atomic number, and note the number of protons; because atoms are naturally electrically neutral, the protons and electrons are usually equal. Look at the oxidation number for further information.
- Look for the element on the periodic table
Each element is represented by a one- or two-letter abbreviation on the periodic table. For example, H is hydrogen, He is helium, Li is lithium, etc. Consult a reference chart if necessary.
- Look for the atomic number
The atomic number is usually in the top-left or top-center of the square containing the element's information. This number tells you how many protons, or positively charged particles, the elements' atoms have. In many cases this will be the same number as electrons, but this is not guaranteed.
- Look at the oxidation number if necessary
Although most elements have the same number of electrons and protons in their atoms, an element can lose or gain electrons as part of a chemical reaction. You might see the oxidation number, something like 2+ or 3-. This tells you about the relationship between the two. For example, if you see Na+1, you know that sodium has a net charge of 1. It therefore has 11 protons and 10 electrons until it reacts with something else like chlorine.