An element's identity is determined by its atomic number, which corresponds to the number of protons in the nucleus of its atoms. The atomic number is a fundamental characteristic of an element and is unique to each element. For example, hydrogen has an atomic number of 1, which means it has one proton in its nucleus. Carbon has an atomic number of 6, indicating the presence of six protons in its nucleus.
The number of protons is significant because it determines the element's chemical properties and its placement on the periodic table. Elements with different atomic numbers have different arrangements of electrons, which directly influences their chemical behavior, such as their reactivity, bonding capabilities, and overall behavior in chemical reactions.
In summary, the atomic number, represented by the number of protons, is the primary factor that determines an element's identity. It is a fundamental characteristic that distinguishes one element from another and governs its chemical properties.