they define one atom of carbon 12 to be exactly 12 so that they can assign numbers to the others relative to this. because using the actual masses would make the maths ridiculous. the average mass of carbon isn't exactly 12 because not just carbon 12 exists other isotopes do to
Yeah, I don't know why but for AQA they reckon it's dot on 12
Carbon-12 is used as the basis of relative masses of other atoms and molecules, so maybe that's why they say it's 12.
But yeah, it couldn't possibly be exactly 12. I assume that AQA must have mentioned Carbon Dating, which uses Carbon-14, at some point in your time of studying?
Carbon-12 is used as the basis of relative masses of other atoms and molecules, so maybe that's why they say it's 12.
But yeah, it couldn't possibly be exactly 12. I assume that AQA must have mentioned Carbon Dating, which uses Carbon-14, at some point in your time of studying?
I believe it is because carbon-12 is the standard on which the system is based, defined by the fact that the Mr of a neutron or proton is 1/12th of carbon-12. I could be wrong though.
My uni article I used for a lab report said 12.0000000 (can't remember how many decimal places it was)
Surely its something to do with a molecular unit being 1/12th of a carbon-12 atom?
Using my periodic table, it says 12.01. And also, when you say "Mr of Carbon", you're thinking the mass of a single Carbon Atom. Therefore, it could either be 12, 13 or 14 (plus more).
Using my periodic table, it says 12.01. And also, when you say "Mr of Carbon", you're thinking the mass of a single Carbon Atom. Therefore, it could either be 12, 13 or 14 (plus more).
This is only A level. I'm certain the 12.01 is to account for isotopes. But if you're using one Carbon-12 atom then it will be 12. I need to look more into it (and no doubt I will sooner or later) but since carbon-12 is the most common isotope I think that was used as a rekative mass for all other atoms.
Though if I am wrong, I am exceedingly tired. That is why.
because everything is relative to Carbon. there are 12 electrons, each weighing 1.
No, for the love of God, no. Electrons weigh 1/1838, or something like that (trying to remember A-level Chemistry). In any case, there are only 6 electrons in carbon. It's the protons and neutrons that weigh one each.
1 atomic mass unit is defined to be 1/12th the mass of a 12C atom. Everything is measured in atomic mass units, so 12C is therefore defined to weigh 12 amu. The number on your periodic table is the average mass of all isotopes by % abundance, which seeing as all isotopes of carbon weigh 12 or more amu, has to be over 12.