What is the formula for calculating the number of neutrons in an atom?

The formula Neutrons = Atomic mass - Atomic number accurately represents how to calculate the number of neutrons in an atom. The atomic mass (or mass number) of an element indicates the total number of protons and neutrons in the nucleus of an atom. The atomic number, on the other hand, defines the number of protons present in the nucleus.

To find the number of neutrons, subtract the number of protons (atomic number) from the total number of nucleons (atomic mass). This effectively gives you the number of neutrons because neutrons and protons together comprise the atomic mass. Thus, this formula is essential for determining the neutron count in any given element.

In the context of the other options, the first choice suggests adding atomic mass and atomic number, which would be incorrect since it doesn't represent a valid relationship for calculating neutrons. The third option implies that neutrons can be calculated by adding protons and the atomic number, which misunderstands the relationship between these quantities. The last choice incorrectly states that neutrons can be found by subtracting electrons from protons, which is not a measure of neutrons at all and misrepresents how these subatomic particles interact.