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After all, hydrogen is by far the most common element in the universe, and oxygen and carbon are also relatively common.

Hydrogen is only around 3% of the universe, and growing scarcer all the time.

Two different things. Hydrogen comprises 75% by mass of the elements in the universe. http://www.webelements.com/per...

If you are saying it's only 3% of the universe, you must be including dark matter. But that's not an element.

Planets don't, in general, contain dark matter, so the abundance of hydrogen relative to dark matter isn't really relevant to the amount of water found on Pluto and other solar system objects.

It's actually more like 92lbs/ mi^3. http://www.webelements.com/gold/ quotes sea water values at 10 nanograms/Liter.

No, the page you reference just pulls that number out of thin air, and even admits to doing so by saying that "perhaps" that is the concentration. Much more detailed information is here: Gold in Seawater, which quotes a figure about a thousand times less.

This article states that people used to think seawater has much more gold than is estimated today, so that my explain your estimate.

But if you want to extract gold (or anything else) from seawater, you would probably start with the effluent brine from a desalination plant. That way it is already partially concentrated, and may already be pumped up above sea level so you could use gravity to move it through your extraction mechanism.

It's actually more like 92lbs/ mi^3. http://www.webelements.com/gold/ quotes sea water values at 10 nanograms/Liter.

I believe you are correct, but one should keep in mind that simply having a higher atomic number (number of protons and therefore number of electrons in a neutral atom) does not mean a higher atomic radius. In fact, atomic radii decrease as one goes from left to right on a given row on the periodic table.
see http://www.webelements.com/helium/atom_sizes.html

Like the other replies to this post, I completely agree -- I wish more teachers thought like this (and not *just* in chemistry). Teaching chemistry using "theory only" is like teaching programming using pen and paper (which I'm old enough to remember, and greatly resent).

This is about mnemonics. Associate formulas, tables, ratios and reactions with visual memory -- seeing is remembering. Sometimes you don't even have to do the experiment in class -- if something is either dangerous or expensive, there's probably plenty of videos online of the process. This is actually a subject matter in which youtube is a "good resource" (for the visuals, anyway).

Here are a few sites that either give examples of practical/cheap experiments or provide videos of all sorts of chemistry-related material:
thenakedscientists.com
http://www.rsc.org/education/teachers/learnnet/videoclips.htm
http://www.planet-scicast.com/experiments.cfm

Here are a few additional online chemistry resources (the more visual information, the better):
webelements.com
chemicool.com
periodictable.com
periodicvideos.com
practicalchemistry.org
mindat.org

It's like any other subject -- get the students *interested* in _topic_, and they'll teach themselves.

Just hope that an alternative for Lithium isn't found in the mean time.

Probably will be. A very cursory web search brought up this. Seems likely that given some time, other reasonable deposits will be found. This actually makes it harder on Bolivia - they have a fairly small window of time (likely years) to figure out how to maximize revenue and hopefully minimize social and environmental issues.

Being the cynic I am, I'm sure it will come out helping some fat cats and mostly screwing over everybody else. But that's just me.

Alright, I suppose I do.

http://www.webelements.com/lithium/biology.html

But only 2.7mg... it'd take 20 times that much hydrogen cyanide to kill me (for reference).

=)

http://www.webelements.com/periodicity/abundance_seawater/ With solar/wind/wave power and new nanomembranes it will be viable to mine the sea for almost all rare elements.

Oh well, I won't mind seeing this technology die cuz I don't think we have the spare silicon

Good job then that the article later clarifies that it's referring to carbon dioxide !

Not that that is gonna be easy to keep at the right temperature either.

Crash and burn!

I agree that at least the crystal structure can't be the sole reason why diamonds are coveted. I should point out that silicon has the exact same crystal structure as diamond, and no one's killing people over that.

It's being called Jadarite for the mine near Jadar where it was found. This is fairly common from what (little) I know of minerology. They note that, because it doesn't actually contain any krypton, it can't officially be called kryptonite.

Still, couldn't they have made a push for another superman-inspired name. Some suggestions are: Jorelite, Kalelite, Metropolite, or Lutherite.

We're talking about money and matter here. Anit-matter costs anti-money, so it's a different problem...

Polonium-210 has, as someone else said, a half-life of 138 days. That means that, if you start on day 1 with 1 gram of Po-210, on day 139 you have 500 milligrams of Po-210 and 500 milligrams of decay products (in this case, Pb-206, (lead) which is stable). On day 277, you have 250 mg of Po-210 and 750 mg of Pb-206. On day 415, you have 125 mg of Po-210 and 875 mg of lead. And so on...

Here's a useful reference.

http://www.webelements.com/webelements/elements/te xt/Po/key.html

So I would consider it an extremely safe bet that the Po-210 was manufactured within the last year, probably within the last three months.

Even a THOUSAND TIMES the lethal dose of .5 mCi would be a mere tenth of a milligram.

At 9196 kg/m^3 ~= 9 mg / mm^3, that's about a hundredth of a cubic millimeter, assuming it was given in elemental form.

The sheer quantity of alpha radiation it produces also explains why it's used in satellites - "The power density of polonium is unique and made it attractive as a power source. One pound of polonium-210 occupies a volume of approximately 3 cubic inches and produces heat at the rate of 3.6 x 10^8 British Thermal Units (BTUs) per minute or about 64 kilowatts of electric power."

You are not right. In many ways.
1. The density of a liquid is dependent not only on the size of the molecules in it, but on their mass, and on the space between them (that's why hot water is less dense than cold water - on average there is more space between hot water molecules than cold).
2. Atomic size is not constant. It does change (not monotonically) with atomic number. You can see how here: Atom radii.
3. ALL molecules have "overlapping" electronic orbitals if you mean that the atoms are sharing some electrons between them - that's what makes them molecules. Not sure what your point is here.
4. Deuterium has about the same atomic volume as hydrogen (where'd you get 40% less?) but the atomic mass is naturally about doubled (1 proton +1 neutron vs 1 proton - and almost all the mass is in the nucleus), thus the density of D2 is twice that of H2.
5. The density difference between D2 and H2 is of no practical value for fuel cells. It'd be worse to use D2 since it's heavier and the increased density comes from the nuclei, not from an increased number of atoms per volume. And you're not getting energy out of the nucleus but out of the rearrangement of chemical (electronic) bonds. At least until we start talking about nuclear-powered cars. Then count me in!

Funny maybe, but wrong. Cs is a solid at room temp. MP=83F
http://www.webelements.com/webelements/elements/te xt/Cs/heat.html
OK, your room might be that warm, especially as it's August, but room temperature is usually defined as 20C - 25C, or somewhere in there.

And the atomic number of molybdenum is... 42

Let's do the math. The hydrogen sits in the space between the atoms in a Pd crystal. We have to find out how many atoms fit in one unit cell, and what the volume of the unit cell is.
Pd has a ccp crystal structure (see here for details). That is convenient, because that means there is one interstitial space per unit cell. The volume of the unit cell is 389.07^3 pm^3 or 5.89 * 10^-29 m^3. When hydrogen is absorbed by Pd, it splits in its atoms: H2 -> 2H. One interstitial space can contain one hydrogen atom. This means one molecule of hydrogen takes up 1.2*10^-28 m^3 in Pd.
At room temperature and pressure an ideal gas takes up 22.4 l/mol. One mol contains 6.022 * 10^23 molecules. This means in the gas, one molecule of hydrogen takes op (22.4*10^-3)/(6.022*10^23) = 3.7* 10^-26 m^3. This is a factor of 315 more than it takes up in the Pd crystal. Indeed the value of 900 is either grossly overstated, or I have made an error in my calculation.

Radionuclides occur in just about every substance on Earth. There no elements that I know of that have no naturally-occuring radioactive isotopes. Many have a large number. They require no active power source to be radioactive, they just are. Power makes zero difference. An example would be the copper used to make the antenna of the RFID embedded chip. There are a lot of radioisotopes for copper - most of them are beta emitters, though, not alpha. You want to tell me you personally check the RFID tags you implant for isotope purity? No? Then you'll be including some of these in everything you implant, according to the usual rules for the frequency of each isotope on Earth. Sorry, you can't escape it by turning the radio off.

Supposedly the atmosphere of Mars is 0.15% oxygen. That's 1500 parts per million. Earth Air has roughly 210,000 PPM, but water on Earth (which Fish extract oxygen from) is only 5 PPM. If the fish manage to extract oxygen without major issues (and there are larger lifeforms in the water than on Earth), I don't think it should be a problem for us humans. Given that Mars has a 300× richer atmosphere than Earth's water, I think we shouldn't have a problem extracting oxygen. To make air we would also need Nitrogen, which is present at 30,000PPM.

With a sufficiently big enough machine, we should be able to provide enough oxygen to burn stuff. Perhaps we can create a form of fuel that contains both hydrocarbons and oxygen. As I understand, most cars have a certain mix of air and gasoline that is actually ignited. Also, supposedly some race cars use nitrous oxide as an oxidizer.

So it should be possible to provide a system that can generate earth-like air from the Mars atmosphere. The primary question is whether the system would be efficient enough that it can be powered by solar or maybe oil based. On the other hand, I believe a nuclear plant would work. Maybe the first step to collonizing Mars to any degree should be to get some power generators over there.

Then you can start making oxygen. Melt the ice to get water. And with the two you should be able to grow stuff. (you'll probably need to bring fertilizer along as well at the beginning, but later you can just recycle dead plants, feces, etc., to save on fertilizer).

Hmmm, this sounds a bit like urban legend to me. First off, while indeed the melting point of platinum is much higher than that of silver (2040 K versus 1235), platinum is twice as dense as silver (21.1 g/cm^3 versus 10.5 g/cm^3). Secondly, while platinum does occur mixed with other metals, those are typically palladium, rhodium, iridium, osmium, and ruthenium -- not silver. Silver also occurs with other metals, but usually lead, zinc, and copper, occasionally gold -- but not platinum. This isn't especially surprising, as their chemistry is quite different, Ag preferring a +1 oxidation state but Pt preferring +2 and +4. The big density difference also suggests they would not occur together as native metals (because in the molten state they would separate, like oil and water).

Finally, it seems odd that if medieval silversmiths were familiar with the metal they would not have named it. After all, medieval (or rather Renaissance) miners and smiths did name other "annoying" substances that interfered with their activities: the name of the element nickel comes from kupfernickel ("Old Nick's copper" or "the Devil's copper"), a German miner's term for the worthless mineral niccolite (NiAs), which looks like a valuable copper ore, copper (I) oxide. The element cobalt was named after the term kobold ("evil spirit"), given by German miners to the useless and somewhat poisonous rocks of cobaltite (CoAsS) that occured in their silver mines. Zinc supposedly has its name in the German word for "sharp point" because it formed spiky crystals in certain refineries. And so on.

Anyway, it seems hard to believe if Pt was a common annoyance in early European smithing it wouldn't have been named, and that name reflected in the name of the element. But platinum was known to miners -- it was known as platina del Pinto ("little silver of Pinto" in Spanish) to 18th century Spanish gold miners in the Pinto River basin of Columbia, and it was on that basis that the element was named "platinum" by Ulloa and Sir William Watson in 1748.

Not saying what you've said is definitely wrong, but it seems a little odd.

Hmmm, this sounds a bit like urban legend to me. First off, while indeed the melting point of platinum is much higher than that of silver (2040 K versus 1235), platinum is twice as dense as silver (21.1 g/cm^3 versus 10.5 g/cm^3). Secondly, while platinum does occur mixed with other metals, those are typically palladium, rhodium, iridium, osmium, and ruthenium -- not silver. Silver also occurs with other metals, but usually lead, zinc, and copper, occasionally gold -- but not platinum. This isn't especially surprising, as their chemistry is quite different, Ag preferring a +1 oxidation state but Pt preferring +2 and +4. The big density difference also suggests they would not occur together as native metals (because in the molten state they would separate, like oil and water).

Finally, it seems odd that if medieval silversmiths were familiar with the metal they would not have named it. After all, medieval (or rather Renaissance) miners and smiths did name other "annoying" substances that interfered with their activities: the name of the element nickel comes from kupfernickel ("Old Nick's copper" or "the Devil's copper"), a German miner's term for the worthless mineral niccolite (NiAs), which looks like a valuable copper ore, copper (I) oxide. The element cobalt was named after the term kobold ("evil spirit"), given by German miners to the useless and somewhat poisonous rocks of cobaltite (CoAsS) that occured in their silver mines. Zinc supposedly has its name in the German word for "sharp point" because it formed spiky crystals in certain refineries. And so on.

Anyway, it seems hard to believe if Pt was a common annoyance in early European smithing it wouldn't have been named, and that name reflected in the name of the element. But platinum was known to miners -- it was known as platina del Pinto ("little silver of Pinto" in Spanish) to 18th century Spanish gold miners in the Pinto River basin of Columbia, and it was on that basis that the element was named "platinum" by Ulloa and Sir William Watson in 1748.

Not saying what you've said is definitely wrong, but it seems a little odd.

Aluminium and Caesium are the correct IUPAC spellings of those elements for historical reasons.

Caesium comes straight from the Latin caesius for the color sky blue, which is the most prominent line in the element's emission spectrum. Aluminium was so named because many elements at the time had -ium suffixes, and is the official spelling endorsed by the International Union of Pure and Applied Chemistry. The American Chemical Society, however, uses "Aluminum".

The superheated water and H2 come from the magnesium metal reacting with water.

Unfortunately magnesium doesn't normally react with water. Magnesium does react with steam however but the article fails to mention what energy source is used to boil the water.

All about magnesium:
http://www.webelements.com/webelements/elements/te xt/Mg/chem.html/

And because neither of the above really explains anything, here's a better explanation of Bulk Modulus (With lots of neat graphs & charts on the left side of the page)

The isotope of Uranium currently used in commercial reactors is U-235, which constitutes about 0.7% of all naturally occuring Uranium. Other types of reactors can use the remaining 99.3% of Uranium or the much more common Thorium as fuel.

Integral fast reactors produce much less waste because they burn the fuel more completely. They're not even close to waste-free, but their waste isotopes are shorter lived, and the long-term radioactive waste produced (reactor structure etc) is much smaller in quantity. Pebble bed reactors produce their waste contained in nigh-indestructible (usually silicon carbide?) pebbles that are easier to dispose of safely.

There's thousands of years of fuel, even at substantially increased demand.

Can you blame them for holding back on announcing the discovery? After all, it would be very embarassing to the astronomer community to retract such an important discovery, like the chemists did with Ununoctium.

The best resource out there is probably http://www.webelements.com/. Everything from simple tables to in depth data.

Please note that the metal is called Aluminium. Leaving out the i makes you sound like a redneck.

http://www.webelements.com/webelements/elements/te xt/Al/key.html

Now, let's orbit these solar cells at 500 km altitude, i.e. a diameter of 13,756.3 km or circumference of 43,217 km. The article doesn't say how wide the ring should be, but to block 1.6% of the sunlight to a circle 12,756.3 km in diameter would require a strip about 160 km wide. That's 6.9 million square kilometers of solar cells in the full ring.

Now the silicon wafer in a solar cell is really quite thin, typically around 300 microns thick, so that's only 2.074 cubic kilometers of silicon all up. Density is 2330 kg/m3, so that's 4,833 megatonnes of silicon required, or about 0.0000005% of the earth's resources. I think we have enough.

Of course, the energy required to manufacture that sort of area of solar cells would be pretty high, but think of the returns. The earth receives about 1370 W/m2 in orbit, so multiply that by the area of cells facing the sun (2.04 million square km), and you get about 2.8 billion MW of incident radiation :-) Let's say these cells aren't particularly efficient, maybe 10%, plus transmission losses of another 70%, and you still have 84 million MW of usable energy, all day, every day.

Now, in 1997 we used 380 quadrillion BTUs, globally, or about 111 quadrillion watt-hours. That's an average consumption of 12 million MW, comfortably within our budget for some time. An energy-producing system with a capacity of 7 times the entire global requirements is worth quite a bit.

There's only one downside to this - if we divert all this energy down to earth & use it, it all ends up as heat in the end, which completely nullifies the original purpose of the ring (if you remember) of preventing global warming! D'oh!

Narrowly speaking, not a metal, as you say.

More odd seeming to me is calling the material Plutonium. Looking at an online Periodic table http://www.webelements.com/ at plutonium shows a discovery date of 1940 at Berkely by bombardment in a cyclotron so it is vaguely possible that the name was in the literature before the Manhattan project gets underway in 1941 and people start self censoring their submissions to journals on atomic fission and related info (again CF The Making of the Atomic Bomb ).

What this document does tell us is (if real) is that the Germans had started thinking about the bomb in detail, but had only theoretical knowledge of plutonium. They clearly had no practical experimental knowledge or this design would be out the window. This still matches with what had been thought of their program previously.

Given that Xenon is one of the noble gases in the periodic table, would it be appropriate to suggest this may be "vapourware"?

From memory, the further down from Hydrogen, the better the reaction with water.

and Gallium

weight = mass*gravity
mass = density*volume
density is simply a material parameter, so assume we are comparing two wires of the same material
volume = length*pi*radius^2

However you can not treat CNT with the same simple analysis of something such as copper. CNT are sort of like hoses (empty on the inside, having a matrix of carbon on the outside). I assume that it is not 10* better than traditional copper cables, but rather 10* better than copper when you compare material conductivity (see here for a description of the inverse of conductivity, resistivity).

Hmm. The abundance of ruthenium is about 1 ppb in the crust, so that would be about 10^14 kg. IIRC, you need only a few mg of pure Ru per square meter, so I don't think this is the issue. Of course, it might be hard to extract that kind of amounts from the crust, but that is a different story. My old 1986 edition of the CRC Handbook of Chemistry and Physics lists a price of US$4 per gram.

I agree that the dye is expensive, but I think that that has more to do with the fact that it is a complicated organic molecule that surrounds the ruthenium atom.

HOWEVER, that only applies to the elemental form. Certain compounds containing Selenium are highly toxic, and it is my guess that this is what the genetic engineers were interested in.

To quote from WebElements:

Selenium can be prepared with either an amorphous or crystalline structure. Crystalline monoclinic selenium is deep red; crystalline hexagonal selenium, the most stable variety, is a metallic grey (see picture above). Elemental selenium is relatively nontoxic and is considered to be an essential trace element. However, hydrogen selenide (H2Se) and other selenium compounds are extremely toxic, and resemble arsenic in their physiological reactions. Hydrogen selenide in a concentration of 1.5 ppm is intolerable to man. Selenium occurs in some soils in amounts sufficient to produce serious effects on animals feeding on plants such as locoweed (an American plant) grown in such soils.

Webelements lithium page

Crossfire can get free and nobody will sue them. But if they re-name themselves "Crossfire Scholar", they will have a trademark problem too.

Here are a few others that use the term Scholar in their product name - will the ACS sue them too (I think the Rhodes Scholars for one would win):

1. Ron Brown Scholar Program http://www.ronbrown.org/
2. Webelements Periodic Table of the Elements - Scholar Edition http://www.webelements.com/webelements/scholar/
3. Jenses's Scholar's Guide to Humanities and Social Science http://tigger.uic.edu/~rjensen/
4. The Black Scholar http://www.theblackscholar.org/
5. Scholar's Bookshelf http://www.scholarsbookshelf.com/
6. Fulbright US Scholar Program http://www.cies.org/us_scholars/
7. Christian Scholar's Review http://www.hope.edu/resources/csr/
8. Scholar and Femenist Online http://www.barnard.edu/sfonline/
9. ScholarSite.com http://www.scholarsearch.net/
10. Warrior-Scholar.com http://www.warrior-scholar.com/
11. Tennessee Scholar Dollars http://www.tnscholardollars.com/
12. MAA Scholar http://www.maa.mhn.de/scholar.html
13. Scholar Inc. http://www.scholarinc.com/
14. The Thirsty Scholar Restaurant and Pub http://www.thirstyscholarpub.com/
15. Twisted Scholar Inc. http://www.twistedscholar.com/
16. Midtown Scholar Bookstore http://www.midtownscholar.com/
17. Electronic Scholar http://www.electronicscholar.com/
18. War Scholar http://www.warscholar.com/
19. Rhodes Scholar http://www.rhodesscholar.org/

You are a USDA-certified Troll

If SciFinder is so great, unique, etc., why is the ACS so worried? It's not because of what Google Scholar is now, but what it will become in a few years.

Their actions in firing off a slap-suit say that they are the ones trolling - trying to lock in a market with a dumb lawsuit that has a good chance of being dismissed with prejudice.

Uranium is not the answer. Thorium is.

Thorium is a source of nuclear power. There is probably more untapped energy available for use from thorium in the minerals of the earth's crust than from combined uranium and fossil fuel sources.

Maybe someone made a mistake, but according to webelements, Ni63 has a half-life of 100 years. With that half-life, the material would be considered moderately radioactive.

How about a mercury telescope? Does mercury remain reflective if it freezes? You could make the thing huge, comparatively cheap, and if it solidifies, you could even point it where you want it. -38.83C, sounds about right.

Someone needs to go back to school.

Helium

I assume that the hypothetical object in near-sun orbit does not have much more surface on the side that shows away from the sun that on the side that faces the sun. (For a long cylindrical object this would not hold, but I assumed that we were talking about a somehow "football-field" shaped object that is flat rather than long.)

Ah, I think I see what you're saying. Basically if the surface area of the cooling section is equivalent to the surface area of the warming section, then there will be some difficulty in exhausting the heat fast enough to keep the cold side significantly colder than the warm side. Correct?

I did some research on this to find how NASA does it with the RTGs. It seems they extend vanes off the surface of the RTG to provide enough cooling (image). Conceivably, something similar could be done with the cooling cylinder of the engine(s). Instead of having a solid wall facing the rear, a cylinder with vanes could extend from the back of the station.

As long as we can provide enough cooling area to keep the cylinder(s) cool, we should have a very efficient engine. Even if we allow the rear area to reach 450K, that still gives our engine an efficiency rating of 50% ( (900-450)/900x100) = 50%); which is about 30% more efficient than the more fragile Solar Panels.

Thankfully, 900K isn't hard to deal with materials wise. Iron has a melting point of about 1800 Kelvin, which is quite good for the amount of thermal conductivity you're getting.

Now if you *really* want to go the mirrored route, we could build out station out of Tungsten (expensive!). With a melting point of 3700 Kelvin and more than twice the thermal conductivity, we can make the station far hotter than we could otherwise.

I assume that the hypothetical object in near-sun orbit does not have much more surface on the side that shows away from the sun that on the side that faces the sun. (For a long cylindrical object this would not hold, but I assumed that we were talking about a somehow "football-field" shaped object that is flat rather than long.)

Ah, I think I see what you're saying. Basically if the surface area of the cooling section is equivalent to the surface area of the warming section, then there will be some difficulty in exhausting the heat fast enough to keep the cold side significantly colder than the warm side. Correct?

I did some research on this to find how NASA does it with the RTGs. It seems they extend vanes off the surface of the RTG to provide enough cooling (image). Conceivably, something similar could be done with the cooling cylinder of the engine(s). Instead of having a solid wall facing the rear, a cylinder with vanes could extend from the back of the station.

As long as we can provide enough cooling area to keep the cylinder(s) cool, we should have a very efficient engine. Even if we allow the rear area to reach 450K, that still gives our engine an efficiency rating of 50% ( (900-450)/900x100) = 50%); which is about 30% more efficient than the more fragile Solar Panels.

Thankfully, 900K isn't hard to deal with materials wise. Iron has a melting point of about 1800 Kelvin, which is quite good for the amount of thermal conductivity you're getting.

Now if you *really* want to go the mirrored route, we could build out station out of Tungsten (expensive!). With a melting point of 3700 Kelvin and more than twice the thermal conductivity, we can make the station far hotter than we could otherwise.

Make sure you wear Pb underwear, if you ever want to have kids.

I think Holmium is much less useful.