Wednesday, January 22, 2014

Red, White, Blue

Last night, Palladian was asking about neutrons in the context of blue which naturally led to a late night discussion of how neutrons protect us from being blown up.

Here's a story of another color -- red -- including explosions, isotopes, unpaired electrons, and radioactivity.



original
The name rubidium derives from "deep red" in Latin. Robert Bunsen (yes, that Bunsen) named the element after he and physicist Gustav Kirchoff discovered it burning reddish-purple in a flame. They also found cesium which lies directly below (rhymes with) rubidium and which burned brightly blue (cesium derives from the Latin word for blue).

Burning elements is still important in fireworks and also in modern analytical chemistry techniques such as ICP-MS. Also, a fair number of elements are named after their colors: chlorine, rubidium, cesium, chromium, rhodium, indium, iridium, iodine, etc.

The depiction above implies how weakly rubidum holds its outermost electron and why it so readily gives it up to become Rb+. Most anything can pluck it off. Here's a spectacular video of rubidium hitting water:


Naturally occurring rubidium has two isotopes: the stable 85Rb (72.2%) and the radioactive 87Rb (27.8%).  87Rb is considered only "slightly" radioactive--despite its abundance (it is naturally present in seawater)--because of its extremely long half-life of 1010 years.  Remember that something has to actually decay in order for it to emit radiation.

37 comments:

deborah said...

chick, what is the reaction equation for the rubidium and water?

chickelit said...

@deb: Two steps

First step:

2Rb + 2H2O = 2RbOH + H2 (bubble)

Second step:

2H2 + O2 = 2H20 (boom!)

Net:

2Rb + H2 + O2 = 2RbOH

RbOH is alkaline (a base). That why it's an alkaline metal.

deborah said...

Very cool, thanks :)

chickelit said...

With sodium instead of rubidium, you can actually see the steps in the analogous reaction. The chunk of sodium -- no matter its shape -- skitters over the surface of the water, melting into a ball. The ball dissolves, making NaOH and hydrogen gas which may or may not catch fire depending on how fast the hydrogen dissipates.

deborah said...

That would be cool to see on a video.

chickelit said...

What interesting to note in the cesium explosion is that it blew out the bottom of the vessel. You can see that the cesium actually sank to the bottom before reacting. This is because cesium is much heavier than water unlike the others.

deborah said...

I saw the container blow out, but did not note it fell to the bottom before the reaction occurred.

chickelit said...

I just went back and checked. You see a column of bubbles hit bottom.

chickelit said...

I didn't "see" the cesium but I inferred that cesium made them because bubbles rise not fall.

deborah said...

Okay, I see. I was also associating it with the clink of the tongs on the edge of the container lol.

Lem said...

I thought rubidium was that time I lost Marco Rubio inside the palladium night club... it was rubidium ;)

chickelit said...

I admire your curiosity, deborah.

chickelit said...

@Lem: That joke falls under the rubric of "off-color." ;)

Lem said...

Rubio.. blond.. off-color.. not bad.

Lem said...

I'm still chuckling over Chips Stop Sbottom.

deborah said...

:)

Palladian said...

I missed this thread yesterday, somehow!

Interesting information, chickenlittle!

I've been intending to make a periodic table painting using all the derivatives of elements that have been used to make paints through the ages.

Palladian said...

It's difficult to winnow the list down. Where does cadmium sulfoselenide belong, for instance?

chickelit said...

Where does cadmium sulfoselenide belong, for instance?

You're asking: given a mixture of elements, which one is the chromophore? In that case, I'd say sulfur.

Transition metal ones are easy for the non-chemist and only require you recognize it. Others won't be so easy: red lead vs. white lead?

This sounds like a monograph or book. Has anyone done such an endeavor? "The Chemistry of Pigments"?

Why don't you email me a list of pigments you're stuck on and I'll try and help out. -- maybe save you some time.

chickelit said...

Palladian, did you ever see my Pigments Of My Imagination?

deborah said...

"Green is for emeralds. Beryl and emerald are essentially the same material, viz., Be3Al2Si6O18. The only difference is that emerald also contains about 2% chromium, the source of its green color. Chromium also makes rubies red, and sapphires blue..."

How does the same element do that?

chickelit said...

How does the same element do that?

Think of the chromium having an upstairs and the energy it takes to get up to the second floor is the photon. The different gems "shape" the electronic house of chromium differently, leading to different energies to reach the second floor.

The technical jargon is contained mathematically in crystal field theory.

deborah said...

"The different gems "shape" the electronic house of chromium differently, leading to different energies to reach the second floor."

Can't quite grasp this. Does different energies mean different amount of photons, or energies other than a photon?

I never quite got color observed vs. color absorbed, etc.

I never thought indigo as a color rang true.

chickelit said...

Chromium has electrons. They can move up levels when light impinges, but only to discrete levels -- not part way or half way -- all the way or no way.

chickelit said...

I never quite got color observed vs. color absorbed, etc.

Color wheel, complimentarity...take something away and only see what's left.

chickelit said...

I never thought indigo as a color rang true.

Tell that to Mr. Roy G. Biv.

deborah said...

I will not. It doesn't even make sense, considering the six-color wheel.

chickelit said...

It could be that Mr. Biv was just "buying a vowel" for his mnemonic. Yet its frequency occurs -- frequently. :)

chickelit said...

@Deborah: Do you believe that colors can sum? link

If so, than consider starting with white light and subtracting.

chickelit said...

Wanna know how nerdy I can be? A couple years ago, I planted three young citrus trees in a row: orange, lemon, and lime. I wanted to remember which was which because to my eye they looked the same. Even the young fruit all start green and only turn orange, yellow, and green as they ripen. I could have made signs, but instead, I planted them O, Y, G.

deborah said...

Total geek :)

Yes, I do/did believe in color sum, as it was taught to me in jr. high.
Is it incorrect, because that's a thought-provoking statement.

Very nice post.

chickelit said...

Is it incorrect, because that's a thought-provoking statement.

Sorry, you've lost me.

Very nice post.

Thanks!

deborah said...

I didn't get your meaning when you asked if I believed in the summing of colors, and I could subtract from that.

I did learn in jr. high that white is the combination of all colors, and black is the absence of color.

chickelit said...

deborah said...
I will not. It doesn't even make sense, considering the six-color wheel.

I took this to mean that you didn't understand how given white light, if you took out one color it would appear to be its compliment. To illustrate, take that three color thing I linked at 10:38. Start in the middle at white. Take out the blue (move southeast) and you get yellow orange.

Thanks for bearing with all this and for coming back. I do appreciate it. :)

Palladian said...

Very cool post, chick. Your blog is one of my favorites. Too bad about Carol Herman, though.

And thanks for the offer of help with the piggyments. I'll compile a list of them (may take a while) and ship it off to you.

chickelit said...

I'd love to do that Palladian!

deborah said...

That's neat, I never thought of it that way. Yes, I love these chats also.