No, atoms of the same element cannot have different masses. The mass of an atom is determined by the number of protons, neutrons, and electrons it contains. The number of protons in the nucleus of an atom defines its atomic number and determines the element it belongs to. For example, all carbon atoms have six protons, and any atom with six protons is always carbon.
While the number of protons remains constant for a given element, the number of neutrons can vary among atoms of the same element. These variants, called isotopes, have the same number of protons but different numbers of neutrons. Consequently, isotopes of an element have slightly different masses. However, they still belong to the same element because their atomic number remains unchanged.
Isotopes can have different physical properties and can be useful in various applications, such as radiometric dating and medical imaging. Scientists denote isotopes using the element's symbol followed by the mass number, which represents the total number of protons and neutrons in the atom's nucleus. For example, carbon-12 and carbon-14 are two isotopes of carbon with different mass numbers but the same atomic number, indicating they are both carbon atoms.