Looking at all the salt caves, and the amount in the oceans, there seems to be a lot of salt (NaCl, that is) around. How did this come about as the earth was formed?
If the earth was formed by coalescing of materials similar to those in the asteroid belt - is there evidence that they have even trace amounts of salt?
And given that the (earth’s) moon may have actually been ejecta from the earth, do the moon rocks have traces of salt in them? (or maybe the Chlorine somehow evaporated away?)
How about other planets? Do our studies of those find a significant amount of salt?
Is it that both Sodium and Chlorine were formed during the early stages of the “big bang” and some stuck together and now salt permeates the universe?
According to Wikipedia, sodium is only about 0.18% of the Earth’s total mass, and chlorine only about 0.0076% (I think those figures take into account oceans and atmosphere as well as the solid stuff). There is not really all that much salt. It just seems like a lot because it tends to get concentrated together in just a few places (as rock salt, and in the oceans) and because, when dissolved in water, it tastes so strongly to us humans (which is why the seas seems so salty from what is a tiny amount of salt compared to the amount of water).
Thing is, living things have used other things to make themselves. For example, plants, which make up most of the world’s biomass use potassium in their tissue fluids. Crustaceans, corals, microscopic diatoms, and even larger animals use calcium to make up their skeletons. The way living things move one thing from outside their cells to inside their cells is often in a one to one swap. So to get in a potassium or a calcium, you have to throw out something, something you don’t need. To get in a nitrate, a plant has to kick out something it doesn’t need, like chlorine. And over time, sodium chloride has washed out of the land, into rivers and concentrated in the oceans.
Although it is true that living cells contain more potassium than sodium (animal cells as well as plant cells), all organisms need plenty of both the sodium and the chloride ion in order to live. (There is quite a bit of sodium in a healthy cell, but, in a multicellular organism, even more of it in the fluid that surrounds the cells.) Probably because life first evolved in the oceans, all living things are pretty salty inside, and land dwelling organisms need to take in salt (although they excrete some too).
The reason why NaCL gets concentrated in particular places, like oceans and rock salt deposits, has relatively little to do with living things (unlike, the distribution of some other elements, such as oxygen, calcium and carbon) and much more to do with the fact that NaCl is very soluble in water, but also readily crystallizes out when the water evaporates.
NaCl actually is the main substance that precipitates out if you evaporate sea water; it is not just a matter of it having a “stronger taste” than some other compounds. I think the point is that sodium and chloride compounds tend to be very soluble, and do not readily precipitate out in sea water, the way, say, calcium and carbonate do, so the ions mostly left in the ocean are Na+ and Cl-. The rest precipitate out and form limestone or other compounds on the ocean floor, or never dissolve well in rainwater and don’t make it to the ocean. Of course when seabeds dry out you can then have NaCl deposits formed, sitting on top of, say, limestone. Because salt is relatively rare and is useful to us, we tend to ignore all the limestone and other minerals and think of the salt veins as special deposits, but actually they are only a small part of what has been deposited on the ocean bed.
You are missing my point. I was not comparing its amount to the other compounds dissolved in sea water. I was trying to correct the OP’s misapprehension that sodium and chlorine are very common elements on Earth. I am aware that NaCl is the main substance that is dissolved in sea water. The point however, was that, despite that, there is still only a tiny amount of it in the sea compared to the amount of the water itself. We are inclined to think of seawater as being very salty, but it really does not have very much NaCl in it (even though a good deal more than other dissolved things). Seawater only seems as though it has a lot of NaCl in it because NaCl tastes so strongly.
Oxygen and hydrogen are among the most common elements on Earth. Sodium and chlorine are much, much less common (although many other elements are much, much less common still).
Kids today miss out on all the good stuff. If you don’t know this, you don’t know why Giorgio de Santillana and Hertha von Deschend called their book Hamlet’s Mill.
Modern scientists will try to talk to you about solubility and relative concentrations of elements and ions, but the ever-grinding mill at the bottom of the sea is easier to understand and more believable.