Salt
Table salt dissolves because water is polar: each molecule has a slightly plus end and a slightly minus end. Those ends tug sodium and chloride ions out of the crystal and surround them. The solid looks gone, but the pieces are still in the water.
On this page: why salt dissolves, what salt is made of, how much water can hold, and how to get dissolved salt back.
Read the answer below. In Giant, kids talk with characters and keep the adventure going.
Salt
Table salt is a crystal of sodium and chloride ions locked in a cube pattern. Water molecules are tiny magnets of charge: oxygen leans minus, hydrogens lean plus. The minus ends crowd the sodium. The plus ends crowd the chloride. The crystal lets go. Each ion gets a water coat, called a hydration shell. That is dissolving. The water did not destroy the salt. It unstacked it.
NaCl
Sodium + chloride
Polar
Water's plus and minus
~36 g
Per 100 mL water (room)
Evaporate
How salt returns
The everyday crystal is sodium chloride, written NaCl. Sodium is a metal that would be wild on its own. Chloride comes from chlorine, a gas. Locked together as ions, they make the white grains in a shaker. Sea salt and rock salt are still mostly NaCl, with extra minerals that can change taste and color. Iodized salt has a tiny added iodine compound so people get that nutrient.
A cup of water can dissolve only so much salt. At room temperature, about 36 grams of table salt dissolve in 100 milliliters of water. That packed limit is called saturation. Extra crystals sit on the bottom. Hotter water can usually hold a little more. The ocean is salty, but it is nowhere near that packed limit. That is why a shaker still disappears in a glass.
Yes. If you boil or evaporate the water, the ions meet again and rebuild crystals. That is how sea-salt farms work: shallow ponds, sun, leftover white crust. You can try a tiny version in a pan with help from a grown-up. The salt was never gone. The water was hiding it.
In Giant
Kids talk with characters, create adventures, and discover how the world works.
Explore
