Why is Chlorine in its position on periodic table? Can it fit into another spot?

Chlorine has about 15 known isotopes. Even hydrogen has three.

An elemental isotope has a specific number of neutrons. Neutron content of the nucleus does not affect chemical properties. It’s the electrons that determine an atom’s chemical properties and so set its position in the Periodic Table of the Elements. An atom (not an ion) has the number of electrons equal to the number of protons so that it is neutral. Electrons have an electrical charge exactly equal in absolute value and opposite in sign to protons.

Figuring out how electrons determine chemical properties was one of the great triumphs of quantum mechanics.

Explanation:

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the accuracy of the data.