5 ms·

Here: https://sci-hub.st/10.1126/science.aaz7607 https://sci-hub.st/10.1126/science.aaz7607 And yeah, TFA is a little lame. I laughed at "lithium...floats on w

Here: https://sci-hub.st/10.1126/science.aaz7607 https://sci-hub.st/10.1126/science.aaz7607 And yeah, TFA is a little lame. I laughed at "lithium...floats on water". It's true that it's less dense, but "float" is a huge understatement. That is, it skitters, like water on a hot frying pan. But, I guess because it's less dense, it doesn't detonate as often as sodium or potassium do.

nl 6y ago
> It's true that it's less dense, but "float" is a huge understatement. That is, it skitters, like water on a hot frying pan. No, if you wrapped it in some impermeable coating so it couldn't react with water it would still float. > But, I guess because it's less dense, it doesn't detonate as often as sodium or potassium do. It doesn't "detonate as often" because it is less reactive than sodium and potassium because it is less likely to lose it's outer electron because that outer electron is closer to the nucleus. That also means it is denser.
- mirimir 6y ago
  OK, sure. But TFA doesn't mention any coating. I found a resource that corroborates what I said about behavior on water.[0] But it doesn't get into why that is. And about density and electronegativity: g/cm^3 χ (Pauling) 1st ionization energy (kJ/mol) Li 0.535 0.98 520 Na 0.968 0.93 496 K 0.856 0.84 419 The difference in density is larger than that for electronegativity and 1st ionization energy. But yes, all three arguably play a role. Still, for Li vs Na, density seems like the major factor. 0) https://www.reference.com/science/alkali-metals-react-water-b7495b0b4fb484e2 https://www.reference.com/science/alkali-metals-react-water-...
- jtbayly 6y ago
  Lithium is denser then sodium?
cbhl 6y ago
My high school chemistry teacher lamented that he had fond memories of taking a lump of a metal (sodium, potassium) and watching the fireworks with his students when they threw it in a pond out back. These days, he has to settle for taking a small sliver and dropping it into a beaker of water behind a safety shield.
- mnw21cam 6y ago
  My school teacher chucked a golf-ball-size lump of sodium into the school swimming pool, then declared a wish to see the face of the guy who tests the pH of the pool the next morning.
- TomJansen 6y ago
  Ha! My chemistry teacher did the same! Killed all the fish in the pond one time, or so he said.
- phyzome 6y ago
  A big chunk can jump back out at you, along the original angle of incidence. And it can really fuck up the pond's chemistry. So I endorse not throwing big chunks of alkali metal in ponds. Putting a small lump in a bucket outdoors using a rope-activated rig sounds pretty reasonable, though.
  - mirimir 6y ago
    Sodium in hot concentrated nitric acid is very impressive. As you say, outside with a string-activated rig. Short term, it does kill vegetation. But long term, it's fertilizer.

nl 6y ago

> It's true that it's less dense, but "float" is a huge understatement. That is, it skitters, like water on a hot frying pan. No, if you wrapped it in some impermeable coating so it couldn't react with water it would still float. > But, I guess because it's less dense, it doesn't detonate as often as sodium or potassium do. It doesn't "detonate as often" because it is less reactive than sodium and potassium because it is less likely to lose it's outer electron because that outer electron is closer to the nucleus. That also means it is denser.

mirimir 6y ago
OK, sure. But TFA doesn't mention any coating. I found a resource that corroborates what I said about behavior on water.[0] But it doesn't get into why that is. And about density and electronegativity: g/cm^3 χ (Pauling) 1st ionization energy (kJ/mol) Li 0.535 0.98 520 Na 0.968 0.93 496 K 0.856 0.84 419 The difference in density is larger than that for electronegativity and 1st ionization energy. But yes, all three arguably play a role. Still, for Li vs Na, density seems like the major factor. 0) https://www.reference.com/science/alkali-metals-react-water-b7495b0b4fb484e2 https://www.reference.com/science/alkali-metals-react-water-...
jtbayly 6y ago
Lithium is denser then sodium?

cbhl 6y ago

My high school chemistry teacher lamented that he had fond memories of taking a lump of a metal (sodium, potassium) and watching the fireworks with his students when they threw it in a pond out back. These days, he has to settle for taking a small sliver and dropping it into a beaker of water behind a safety shield.

mnw21cam 6y ago
My school teacher chucked a golf-ball-size lump of sodium into the school swimming pool, then declared a wish to see the face of the guy who tests the pH of the pool the next morning.
TomJansen 6y ago
Ha! My chemistry teacher did the same! Killed all the fish in the pond one time, or so he said.
phyzome 6y ago
A big chunk can jump back out at you, along the original angle of incidence. And it can really fuck up the pond's chemistry. So I endorse not throwing big chunks of alkali metal in ponds. Putting a small lump in a bucket outdoors using a rope-activated rig sounds pretty reasonable, though.
- mirimir 6y ago
  Sodium in hot concentrated nitric acid is very impressive. As you say, outside with a string-activated rig. Short term, it does kill vegetation. But long term, it's fertilizer.