Answer:
Step-by-step explanation:
Two atoms of the same element can have different atomic masses because of the existence of isotopes. Isotopes are atoms of the same element that have the same number of protons in their nuclei (which defines the element) but different numbers of neutrons. Since the atomic mass of an atom is determined by the sum of its protons and neutrons, isotopes of the same element will have slightly different atomic masses due to the variation in the number of neutrons.
For example, let's consider carbon. The most common isotope of carbon is carbon-12 (12C), which has 6 protons and 6 neutrons, resulting in an atomic mass of approximately 12 atomic mass units (amu). However, there is also another stable isotope of carbon called carbon-13 (13C), which has 6 protons and 7 neutrons, leading to an atomic mass of approximately 13 amu.
So, two atoms of carbon, one of carbon-12 and one of carbon-13, are both carbon atoms but have slightly different atomic masses due to the difference in the number of neutrons. This is true for many elements, and the presence of isotopes with different atomic masses is a common phenomenon in the periodic table.