Finding the Protons, Neutrons, Electrons, & Mass Number for Ions

In this video we’ll use the Periodic table and a few simple rules to find the protons, electrons, and neutrons for ions. From the Periodic Table we can find the element symbol, atomic number, and atomic mass. Using this information we can find the other information.

When atoms LOSE electrons, they become positive ions (cations).
When atoms GAIN electrons, they become negative ions (anions)

----Rules----
Atomic Number = Number of Protons
Number of Protons = Number of Electrons (for a neutral element)
Mass Number = Number of Protons + Neutrons
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Resources:
Finding the Protons, Neutrons, and Electrons for Elements:    • Finding the Protons, Neutrons, Electr...  

Finding the Charge for Ions:    • Finding the Ionic Charge for Elements...  

Understanding Isotopes:    • Introduction to Isotopes and Definition  

When we are finding protons, neutrons, and electrons for ions the only thing that will be different between a neutral element and an ion will be the number of electrons. That is because electrons are lost or gained when chemicals bond. The protons and neutrons are not involved in chemical reactions.

The Atomic Mass is usually written below the number. If you are confused the Atomic Mass will be the larger number – think of it as more massive than the Atomic Number. Often it also has decimals.

If you are not given the Mass Number, it’s best to round to the Average atomic Mass to the nearest whole number. For example, with Calcium (Ca) we have 40.08 on the Periodic Table. We can round this to 40.