Someone remind me how chemical notation works again...

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when you are looking at the Elemental symbol the numers in front are the Atomic number and the Atomic Mass.

The Atomic number is the number of Protons
The Atomic mass is the number of protons and Neutrons

The Atomic number IS the element, all have unique numbers.

The Atomic mass defines the Isotope. (This number is ALWAYS bigger than the Atomic number)

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odin wrote:
I know the basic CO<sub>2 notation is two O's glued to one C. But what is it again with superscript number after the atom letter. Electron surplus of deficiency? And what about isotopes? isn't that a subscript number in front of the letter? Or something?

Five years since having had the last chemistry has killed my knowledge quite a bit it seems :-).</sub>

Oh yeah, the Superscript after the Letter is the Charge on the ion.

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T_Bone wrote:
Notation? What the...?

Look, everything is made out of four elements
Air, Water, Earth, and Fire. ;-)

you forgot Wind... and Death... :-D

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Speelgoedmannetje wrote:

KennyR wrote:
(once you have the atomic mass and the number of protons, you can just subtract and get the neutrons)

I know, but I rather think it was something with radiation or so. I've really really forgotten it.

In "nuclear reactions", ie radio active decaty of Uranium 235, one can measure the mass of the resulting nucleus and compare that wit the mass one would expect to get and you end up with a value called the "Mass defect". Using E=MC^2  (where M = the mass defect) one can work out the energy released from the "nuclear reaction"... but this is phisics, and I'm a chemist, so I don't care :crazy: