A urea molecule is a polar molecule. Urea is a compound that contains nitrogen, and is excreted by the kidneys. It is also the main component of urine.
Scientists divide molecules into the categories of polar and nonpolar. A polar molecule is one that has a positive electrical charge on one side and a negative electrical charge on the other. Non-polar molecules have electrical charges that are more equally distributed. One of the defining characteristics of a polar molecule is that it is soluble in water. Non-polar molecules are soluble in fat. In addition to urea, polar molecules include water and ammonia.