What compounds are insoluble in water?
Thanks for you question regarding solubility in water.
Another factor that helps to determine solubility in water is how much is your solvent like water?
Iodine is basically insoluble in water. Iodine is a molecule and water is a molecule. That sounds like they have a lot in common. However, water is a polar molecule and iodine is completely nonpolar. Thus, iodine is not enough like water to be dissolved in water.
Since water is polar, it can also dissolve many ionic compounds. Ionic compounds are totally polar, with positive and negative parts. Water is polar with the hydrogen atoms being partially positive and the oxygen being partially negative. Thus, water dissolves many ionic compounds because it is "like" them.
Polar molecules are often soluble in water as they are "like" water.
The general rule for solubility is: "likes dissolve likes."
I do hope this helps and have a great day.