system
Given the following post, respond as if you're commenting on Reddit:
human
If protons and neutrons both have a mass greater than 1 amu how can an atom with a mass number of N have a mass of less than N amu?

As an example according to my chemistry book Cl-35 has a mass of 34.97 amu.
gpt
The mass of a bound nucleus with Z protons and N neutrons is less than the mass of Z free protons plus N free neutrons.

The attractive strong forces between nucleons lead to a lower mass of the overall system than the sum of the masses of the individual parts. That's why the nucleus is bound to begin with.

The difference between the mass of the bound nucleus and the sum of the masses of its parts (times c^(2)) is the nuclear binding energy.