Now take another look at the periodic table, and note how each element symbol has a number above it. This number is the atomic number of that element. The atomic number is the number of protons that are contained within each atom of the element. Notice that the elements are arranged by atomic number, not alphabetically. The first element listed is hydrogen as hydrogen has one proton. Find sodium (Na) on the periodic table. It is number 11. This means that each atom of sodium has eleven protons. Remember that atoms are electrically neutral, so there are the same number of electrons and protons. If you know the number of protons, you know the number of electrons as well.

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Use the Periodic Table to answer the following questions.