Elements and Atomic Weight and Mass

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ElementA substance that cannot be broken down into simpler substances by chemical means. An element is composed of atoms that have the same atomic number, that is, each atom has the same number of protons in its nucleus as all other atoms of that element.

Atomic Weight and Atomic Mass

Atomic Number: is the number of protons in the atom

This also tells us the number of electrons as protons = electrons to balance the charge on the atom

Atomic weight: is the number of protons and the number of neutrons in the nucleus