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### FL #3 C/P #10

Posted: Sun Sep 10, 2017 5:53 pm
Why is the atomic mass lost in these processes is regarded as negligible?

### Re: FL #3 C/P #10

Posted: Sun Sep 10, 2017 10:12 pm
Hi mshah,

It may be helpful to look at some numbers regarding the mass of subatomic particles.

Proton mass = 1.6726 × 10-27 kg
Neutron mass = 1.6749 × 10-27 kg
Electron mass = 9.1093 × 10-31 kg

A first thing to note is that electrons are WAY smaller than protons or neutrons, by multiple orders of magnitude. The addition or loss of a single electron is going to make virtually no difference to the atomic mass.

Protons and neutrons also have a very similar mass, identical to the first two decimal places. Keeping in mind that 60Co by definition has 60 protons/neutrons, changing one to another really won't make a difference. For the purposes of quickly estimating the atomic mass of a substance, we usually consider both protons and neutrons to have a mass of 1 amu because their masses are so similar that they can be considered equal in most practical scenarios.

I hope this clarifies thing!