Question 29

Electrons have relatively little mass that is considered negligible when calculating the atomic mass number.

Electrons are the component of an atom that possess minimal mass compared to protons and neutrons, making their contribution to the atomic mass number negligible.

A) Neutron

Neutrons have a significant mass that is roughly equal to that of protons and plays a crucial role in determining the atomic mass number. Therefore, they cannot be considered negligible in mass calculations.

B) Proton

Protons also have a mass that is comparable to neutrons and are essential in defining the atomic mass number of an element. Their mass is substantial and cannot be dismissed as negligible.

C) Electron

Electrons are much lighter than protons and neutrons, with their mass being about 1/1836 that of a proton. This minimal mass means that, when calculating atomic mass, electrons are often considered negligible.

D) Quark

Quarks are fundamental particles that make up protons and neutrons, but they are not typically referenced directly in atomic mass calculations. Their masses are also small and do not factor into the atomic mass number as directly as protons and neutrons.

Conclusion

The correct answer is that electrons have negligible mass when calculating the atomic mass number compared to protons and neutrons. All other options, including neutrons, protons, and quarks, involve significant mass contributions that are essential to the atomic mass, thereby confirming that electrons are the only component considered negligible in this context.