A student says: Potassium (K) always has 20 protons. Explain why the student is incorrect.

Explanation:

19

Potassium/Atomic number

This tells you that potassium has 19 protons and - since the number of protons is the same as the number of electrons- also 19 electrons. To find out the number of neutrons you have to look at the atomic mass or weight of the element. This can also be found in the periodic table.

air quality

poor drinking water

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can lead to poor health