What exactly is Chromium 6?

I did run a couple of searches on this, but as with most similar situations, a simple definition was hard to come by, having been swept aside by all the subsequent discussion of effects, prevention, and counteraction.

Chromium is, I know, a metallic element of the first transition series. But I didn’t know it came in different isotopes (if that’s what the distinction is). And if so,
then how can it be ‘6’? Shouldn’t the isotope number be the
atomic weight? AS we all know, 6 is the weight of the ultralight metal lithium.

If it is a matter of isotope, then how does that make it poisonous? The electronic structure should be the same for
all isotopes, no?

Too much Erin Brockovich?

Hexavalent Chromium, as in Cr6+, is one of the oxidized forms of chromium. 6 as in it has 6 more protons in the nucleus than electrons in the shell. Metallic chromium is Cr0. Chromium exists in a number of valencies, IIRC, namely trivalent and hexavalent.

The six refers to the oxidation state of the atom. Chromium 6 will form the equivalent of six bonds to other atoms or molecules.

I’m not sure exactly how this makes it poisonous, but, to take a guess, I’d say that Chromium 6 is more water soluble than other oxidation states. Or, more accurately, the molecules and complexes Cr 6 forms are more water soluble.

I know a doctoral student who is spending her entire academic career studying hexavalent chromium. If you have some specific questions, I can ask her.

Gods alive! :mad: Can no-one use a search engine these days? Go here for the occurence, uses and toxicology of hexa-valent Chromium.
And does no-one learn Chemistry anymore? Those were pretty simple questions that I could have answered when I was about 13yo (spot the geek). Sorry, but feeling a bit pissed off right now, but it’s a good link

Another commonly used oxidation state, in addition to 3 and 6, is +2.
And Mr Wilkinson, very sorry to have disturbed you, we’ll all try harder to ask questions which we specifically know that you didn’t know the answer to when you were 13. Could you provide a list of all those topics we need to avoid? The glow of your omniscience is blinding me.

Hey, don’t rag on me. When I was 13yo I probably knew as much about chemistry as any one of my contemporaries. I loved science such as it usually is presented to pupils of that age. Then someone told me that to be a scientist I’d have to be good at math, which pretty much put the kybosh on that whole idea.

Well nowadays I’m not quite so innumerate as I was all through school, but I remain -

Your mathematically challenged pal,
                         Jim

Much obliged, A. No thanks for now, but I’ll keep you in mind should questions arise in the future.