How do you find the number of electrons in an atom?

The atomic number is the number of protons in an atom of an element. In our example, krypton's atomic number is 36. This tells us that an atom of krypton has 36 protons in its nucleus. read more

The easiest way to find the number of protons, neutrons, and electrons for an element is to look at the element’s atomic number on the periodic table. That number is equal to the number of protons. The number of protons is equal to the number of electrons, unless there’s an ion superscript listed after the element. read more

Valence electrons are the electrons contained in the outermost shell. If you look at the periodic table and at the period numbers, that is the number of valence electrons. If the number is larger than 10, subtract 10 so you get two valence electrons. Example: Oxygen is in the 16th period. read more