Videos and illustrations from Chapter 4, Lesson 1 of the Middle School Chemistry Unit produced by the American Chemical Society
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. To find the number of neutrons, subtract the element’s atomic number from its atomic mass (the number listed underneath the element). To learn how to find the number of electrons if there’s an ion superscript, read on!
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