461
Chemistry / Re: Can Sodium react with water when there is a distance between the two?
« on: 19/07/2021 05:23:15 »
It is very rare that a single atom of sodium would encounter a single molecule of water (this is what would happen in the gabs phase reaction of steam and sodium vapor, so it's not impossible, but probably not relevant to throwing a chunk of sodium in a pond.)
Let's say this "chunk" of sodium is about 1 cm on a side (1 cm3 of sodium = 970 mg of sodium = 2.55×1022 sodium atoms).
One of the properties of metals (one of the *defining* properties, depending on the context) is that the valence electrons are completely delocalized: the proverbial "sea of mobile electrons." It isn't really meaningful to say that the electron came from any one atom (barring defects or other special cases). Thus when an arbitrarily large chunk of sodium comes into contact with water, one could reasonably interpret electrons moving from being centered within the arbitrarily large piece of sodium, to moving into the σ* orbitals of neighboring water molecules. Depending on how you want to define things, it could be an arbitrarily far electron transfer.
One interesting effect of this is that, if the metal is a liquid, the resulting electrostatic forces resulting from this long-range "harpoon" reaction (thanks Bored, I have never come across that term before either, but it is a great concept!), distort the surface of the liquid metal into tiny spikes, thereby increasing the exposed surface area, and this can result in a "Coulomb explosion"
This is excellently demonstrated in this video (best at 15:45): (note: I am aware that the guy who made this video is associated with some controversy, but this particular minute of this video addresses the question very directly).
Let's say this "chunk" of sodium is about 1 cm on a side (1 cm3 of sodium = 970 mg of sodium = 2.55×1022 sodium atoms).
One of the properties of metals (one of the *defining* properties, depending on the context) is that the valence electrons are completely delocalized: the proverbial "sea of mobile electrons." It isn't really meaningful to say that the electron came from any one atom (barring defects or other special cases). Thus when an arbitrarily large chunk of sodium comes into contact with water, one could reasonably interpret electrons moving from being centered within the arbitrarily large piece of sodium, to moving into the σ* orbitals of neighboring water molecules. Depending on how you want to define things, it could be an arbitrarily far electron transfer.
One interesting effect of this is that, if the metal is a liquid, the resulting electrostatic forces resulting from this long-range "harpoon" reaction (thanks Bored, I have never come across that term before either, but it is a great concept!), distort the surface of the liquid metal into tiny spikes, thereby increasing the exposed surface area, and this can result in a "Coulomb explosion"
This is excellently demonstrated in this video (best at 15:45): (note: I am aware that the guy who made this video is associated with some controversy, but this particular minute of this video addresses the question very directly).
The following users thanked this post: Eternal Student