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You need to know the atomic number to know how many electrons an atom has. You can find it next to the element's symbol on the Periodic Table.

For example, lithium has an atomic number of 3. This tells us that a lithium atom has 3 protons. Now since atoms are neutral they must have the same number of protons and electrons, so lithium also has 3 electrons.

Atoms can lose or gain electrons to become charged species called ions, in which the number of electrons will not equal the number of protons; however, in a neutral atom:

atomic number = number of protons = number of electrons

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15y ago

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