Final answer:
Atomic weight is primarily determined by the number of protons and neutrons in an atom, with protons and neutrons each contributing about 1 atomic mass unit. In contrast, electrons are negligible in mass relative to these particles. Thus, understanding these subatomic particles is essential in determining atomic weight.
Explanation:
Understanding Atomic Weight
Atomic weight, also known as atomic mass, is largely determined by the number of protons and neutrons in an atom. These two subatomic particles contribute most significantly to an atom's mass, while electrons have a negligible mass in comparison. To illustrate:
- Protons are positively charged particles found in the nucleus and each proton has a mass of approximately 1 atomic mass unit (amu).
- Neutrons are neutrally charged particles also located in the nucleus and, like protons, have a mass of about 1 amu.
- Electrons, which are negatively charged, orbit the nucleus and have a mass that is about 1/1836 that of a proton, making them insignificant in the calculation of atomic weight.
Therefore, the correct choice among the provided options is the number of protons and neutrons.
Learn more about Atomic Weight here:
https://brainly.com/question/3909004