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1500 questions
251
votes
3 answers
Why is gold golden?
Bulk gold has a very characteristic warm yellow shine to it, whereas almost all other metals have a grey or silvery color. Where does this come from?
I have heard that this property arises from relativistic effects, and I assume that it has to do…
tschoppi
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237
votes
1 answer
Why can we smell copper?
If I can smell an object, it means that molecules of it are getting separated from it, so they can reach my nose. As far as I know, metals don't sublimate, especially not in room temperature. However, copper has a very strong and characteristic…
vsz
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181
votes
8 answers
Can an atom have more than 8 valence electrons? If not, why is 8 the limit?
According to some chemistry textbooks, the maximum number of valence electrons for an atom is 8, but the reason for this is not explained.
So, can an atom have more than 8 valence electrons?
If this is not possible, why can't an atom have more…
moonw
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144
votes
7 answers
Why doesn't water burn?
Hydrogen is flammable, and for any fire to burn it needs oxygen. Why does a compound made of hydrogen and oxygen put out fires instead of catalyzing them? I understand that hydrogen and water are chemically different compounds, but what causes water…
Prageeth Saravanan
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125
votes
8 answers
Why is absolute zero unattainable?
We were dealing with the Third Law of Thermodynamics in class, and my teacher mentioned something that we found quite fascinating:
It is physically impossible to attain a temperature of zero kelvin (absolute zero).
When we pressed him for the…
paracetamol
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122
votes
7 answers
Is a negative pH level physically possible?
A friend of mine was looking over the definition of pH and was wondering if it is possible to have a negative pH. From the equation below, it certainly seems mathematically possible—if you have a $1.1$ (or something $\gt 1$) molar solution of…
apnorton
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114
votes
1 answer
Is there a general consensus on the causes of the alpha-effect?
There have been various explanations posited for the α-effect. The α-effect refers to a phenomenon wherein nucleophiles with lone pairs on atoms adjacent (i.e., in the α- position) to the atom bearing the reacting lone pair sometimes exhibit…
Greg E.
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108
votes
5 answers
How do you melt metals with super high melting points?
At the Renaissance fair a few years back I was watching a smith forge metal into shapes. During this time a very odd question came to me. I was wondering what the furnace was made of. My logic stated that whatever the furnace was made of must have a…
Griffin
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101
votes
7 answers
Is it actually possible to dispose of a body with hydrofluoric acid?
In the TV show "Breaking Bad", Walter White frequently gets rid of people who get in his way by submerging them in a plastic container full of hydrofluoric acid. This, at least in the TV show, completely dissolves the body leaving nothing but a red…
user1579
97
votes
2 answers
What is Bent's rule?
I'm all bent out of shape trying to figure out what Bent's rule means. I have several formulations of it, and the most common formulation is also the hardest to understand.
Atomic s character concentrates in orbitals directed toward…
Dissenter
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97
votes
7 answers
Why is the 2s orbital lower in energy than the 2p orbital when the electrons in 2s are usually farther from the nucleus?
My chemistry book explains that even though electrons in the $\mathrm{2p}$ orbital are closer to the nucleus on average, electrons from the $\mathrm{2s}$ orbital spend a very short time very close to the nucleus (penetration), so it has a lower…
Gordon Gustafson
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96
votes
7 answers
Is toothpaste solid or liquid?
My teacher didn't answer this properly:
Is toothpaste solid or liquid?
You can't say toothpaste is a solid because solid material have a fixed shape but toothpaste doesn't. However, you can't say it's a liquid because liquids flow easily but…
Simon-Nail-It
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87
votes
5 answers
Does water really 'go bad' after a couple of days?
Among my friends it is a sort of 'common wisdom' that you should throw away water after a couple of days if it was taken from the tap and stored in a bottle outside the fridge, because it has 'gone bad'.
First of all, the couple of days is not very…
Michiel
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86
votes
5 answers
Is it true that heavy water is not blue?
I believe I saw this claim somewhere on the internet a long time ago. Specifically, it was claimed that the difference could be observed by filling one long, straight tube with light water and one with heavy water, and looking through both tubes…
Brian
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86
votes
3 answers
If nothing sticks to Teflon, how does Teflon stick to frying pans?
The most notable characteristic of polytetrafluoroethylene (PTFE, DuPont's Teflon) is that nothing sticks to it. This complete inertness is attributed to the fluorine atoms completely shielding the carbon backbone of the polymer.
If nothing indeed…
user95