A quick discussion on the amu (atomis mass unit)

[DoesntMatter]

In another thread I was repeatedly told I was wrong, with much discussion, on one of the most basic ideas in all of general chemistry. So here, let's keep this clean and discuss it without much namecalling

When you discuss the mass of an element, in terms of its mass per atom, it is usually given it amu's, which stands for atomic mass units. When you look at the atomic mass of some element, it is given as a weighted average of all the naturally occuring isotopes found in nature

For instance, the element carbon has I think 3 naturally occuring isotopes: carbon-12, carbon-13, and carbon-14. Each has a different mass. When the atomic mass of "carbon" is calculated, it is done like this: Let's say C-12 has 98% abundance in nature, C-13 1% abundance, and C-14 1% abundance. Then you multiply the mass of each isotope by its percent abundance in natural and sum it up. In the case of carbon, this is about 12.0107 amus

But what is an amu? It is, by definition, 1/12th the mass of a single carbon-12 atom. Carbon-12 is defined as being 12 amus in atomic mass. EXACTLY 12.0000000000000000 amus in atomic mass

How come? Because it is easier to measure atomic masses of other atoms relative to that of another (as opposed to giving each an absolute mass). Here's a page that explains that

[url]http://www.iun.edu/~cpanhd/C101webnotes/composition/mass.html[/url]



SO:
Carbon-12 is the only isotope that has an integer, non-decimal atomic mass

[Only-virgins]

[url]http://en.wikipedia.org/wiki/Carbon[/url]

"Standard atomic weight 12.0107(8) g·mol−1"

Copied and pasted.

[DoesntMatter]

OV: The mass of the element carbon and the mass of strictly the isotope carbon-12 are two different things

Calculating the mass of carbon includes in its calculation the mass of carbon-12

Again, as I showed in my example: Knowing Carbon-12 is 98.93% of the carbon in nature and carbon-13 is 1.07%, the atomic mass of carbon is:

atomic mass of carbon = (0.9893)×(12.000amu) + (0.0107)×(13.003amu)

= ~12.01 amu

Get it now? That number you keep saying to be the mass of carbon-12 is the atomic mass of carbon, accounting for all its isotopes

[Only-virgins]

OV: The mass of the element carbon and the mass of strictly the isotope carbon-12 are two different things

Calculating the mass of carbon includes in its calculation the mass of carbon-12

Again, as I showed in my example: Knowing Carbon-12 is 98.93% of the carbon in nature and carbon-13 is 1.07%, the atomic mass of carbon is:

atomic mass of carbon = (0.9893)×(12.000amu) + (0.0107)×(13.003amu)

= ~12.01 amu

Get it now? That number you keep saying to be the mass of carbon-12 is the atomic mass of carbon, accounting for all its isotopes

What do you mean "Do I get it now?" 12.01 as I said. I always speak of things the way they are in nature. Do YOU get it now?

[Only-virgins]

I'm not sure wikki is your best source, OV.



"Carbon-12 is of particular importance as it is used as the standard from which atomic masses of all nuclides are measured: its mass number is by definition 12."

[url]http://en.wikipedia.org/wiki/Carbon-12[/url]

The source is correct, it isn't the only one I can provide if you want me to spend all day posting from everywhere that 12.0107 is the amu of carbon. In nature, if that tickles DM more.

[DoesntMatter]

The source is correct, it isn't the only one I can provide if you want me to spend all day posting from everywhere that 12.0107 is the amu of carbon. In nature, if that tickles DM more.

BOTH pieces of information were correct. How many times must I say this? The mass of carbon accounts for all it's isotopes most likely in any given sample: it ends up being 12.01 amus

The mass of carbon-12, which is an isotope of carbon is exactly 12 amus by definition. There is an exremely important difference between the two. You were saying I called it to be 12 amus as a convience for rounding in a lab- not at all

[IndiReloaded]

LOL, DM. Why don't you just post the contents of Stryer for everyone? Hahaha.

Take some more medication, kiddo, your OCD is getting out of control. ;

[Only-virgins]

You are posting everything I already know. The original debate was the atomic weight of Carbon. It is really getting tiring of having you post the same shit over and over again.

[doppelgaenger]

Haha, you guys let a little CO2 get to your noggins or what?

[Only-virgins]

Haha, you guys let a little CO2 get to your noggins or what?

You should visit where I work, it gets worse than this.

[1averagejoe]

Man I'm not looking forward to Chemistry next year...I love sciences, but Chemistry, ugh. The one part I really hate.

[doppelgaenger]

You should visit where I work, it gets worse than this.

You're joshing?

Man I'm not looking forward to Chemistry next year...I love sciences, but Chemistry, ugh. The one part I really hate.

I thought I'd hate chemistry. But I got a B. I liked doing everything except being in the lab with chemicals and putting together models with stupid pieces that looked like legos.

Biology, I loved looking at fossils. I loved dissecting owl pellets and examining animal remains. But killing and dissecting animals, I didn't like. And I hunt and clean some of the food I eat!

[1averagejoe]

except being in the lab with chemicals

I learned first hand that concentrated nitric acid is a corrosive my sophomore year in high school...literally.

Oh and it turns your skin yellow, lol.

[Only-virgins]

I learned first hand that concentrated nitric acid is a corrosive my sophomore year in high school...literally.

Oh and it turns your skin yellow, lol.

lol

____________________________

[IndiReloaded]

Part of DMs point was that he thinks I only give him shit for his posts & ignore OV being a dick. He wasn't around when I used to tell OV the same stuff. LOL, I feel like you two are my kids.

OV graduated, grew up, got a degree and a job. Can't wait for DM to do the same.

And he got the same offer you did, DM. But I think you are lost to medicine, unfortunately.