An atom's identity is primarily determined by the number of protons in its nucleus, which is known as the atomic number. The atomic number defines the element to which the atom belongs. For example, an atom with one proton is hydrogen, while an atom with six protons is carbon.
In addition to the number of protons, the arrangement of electrons around the nucleus and the number of neutrons are also important for defining the properties of the atom. Variants of the same element that have different numbers of neutrons are called isotopes, and they can have different physical properties but the same chemical properties, as they have the same number of electrons and protons.
To summarize, the key factors that determine an atom's identity are:
- The number of protons (atomic number).
- The number of neutrons (which defines isotopes of an element).
- The arrangement of electrons (which influences an atom's chemical behavior).
1 answer