No, each atom of an element does not always have the same number of neutrons. While the number of protons in an atom determines the element's identity (atomic number), the number of neutrons can vary, resulting in different isotopes of that element.
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This means isotopes of an element have different mass numbers. The variation in the number of neutrons does not significantly affect the chemical properties of an element, but it can impact the atomic mass.
For example, carbon has three isotopes: carbon-12 (6 protons, 6 neutrons), carbon-13 (6 protons, 7 neutrons), and carbon-14 (6 protons, 8 neutrons). These isotopes have slightly different atomic masses due to the different number of neutrons.
The presence of isotopes is common in nature, and elements often exist as a mixture of isotopes. The proportions of these isotopes can vary, and the atomic mass of an element is typically reported as a weighted average of the masses of its naturally occurring isotopes.