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How does the number of protons determine an element’s atomic number?

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Periodic table of the elements with color-coded categories and labeled element groups, showing atomic numbers, symbols, and basic information for each chemical element. — periodic table Modern version of the periodic table of the elements. To learn an element's name, atomic number, electron configuration, atomic weight, and more, select one from the table.

The atomic number of an element is defined as the number of protons contained within the nucleus of its atoms. Because every nucleus of a specific chemical element contains the same number of protons, this quantity serves as the fundamental characteristic that distinguishes one element from another.1234

On the periodic table, elements are arranged in order of increasing atomic number. Consequently, the number of protons not only identifies the element but also dictates its specific position within the periodic system. For example, an atom with 6 protons is identified as carbon, while an atom with 26 protons is iron. In a neutral atom, this number of protons is also equal to the number of electrons orbiting the nucleus.35412