I've read this excerpt from Wikipedia countless times, but I'm still confused:

The Avogadro number is the approximate number of nucleons (protons or neutrons) in one gram of ordinary matter.

Shouldn't that be "in one mole"?

The quote you have used is there just behind the Avogadro constant([$$\pu{mol-1}$$])/Avogadro number(unitless) definition. Many true statements can be misinterpreted, if quoted or considered out of their context.

Notice the approximate. It is not the definition.

• $$\pu{1 mol}$$ is by definition the amount of matter consisting of exactly $$N_\mathrm{A} = \pu{6.02214076E23}$$ particles(or generally any formal constituent objects).
• The molar mass of nucleons ( protons or neutrons) is approximately $$M_\text{nucleon} \approx \pu{1 g/mol}$$.
• Practically all the mass of ordinary matter is due its nucleons.
• Therefore, $$\pu{1 g}$$ of ordinary matter contains approximately $$N_\mathrm{A}$$ nucleons, as it contains approximately $$\pu{1 mol}$$ of them.

Imagine this:

• I say that the current definition of kilogram is based on the fixed value of the Planck constant.
• I then say $$\pu{1 kg}$$ is the approximate mass of $$\pu{1 L}$$ of water.
• Does it mean I say the kilogram is defined as the mass of $$\pu{1 L}$$ of water? Of course it is not.
• The subject and predicate should be reversed! One gram of matter contains approximately Avogadro's number of nucleons [protons + neutrons] [but not Avogadro's number of electrons unless the substance is protium or possibly the natural mix of H2] Nov 25, 2022 at 23:29
• @jimchmst Electrons were not talked about. :-) Nov 26, 2022 at 0:14
• @jimchmst Not really in this context. Nov 29, 2022 at 22:58
• @jimchmst If I say 1 kg is the approximate mass of 1 dm3 of water, it does not meant 1 kg is defined as the mass of 1 dm3 of water. Nov 29, 2022 at 23:13
• @jimchmst It is there just behind the definition. If he used a broader quote... If it fooled 1 person, than it is still great. Many correct statements fool multiple persons misinterpreting that. Especially if quoted out of context. Dec 1, 2022 at 5:49