Final answer:
Polar substances that interact readily with water are hydrophilic, while nonpolar substances that do not interact well with water are hydrophobic.
Step-by-step explanation:
As a result of water's polarity, each water molecule attracts other water molecules because of the opposite charges between water molecules, forming hydrogen bonds. Water also attracts or is attracted to other polar molecules and ions. A polar substance that interacts readily with or dissolves in water is referred to as hydrophilic (hydro- = 'water'; -philic = 'loving').
In contrast, nonpolar molecules such as oils and fats do not interact well with water, as shown in Figure 2.14 and separate from it rather than dissolve in it, as we see in salad dressings containing oil and vinegar (an acidic water solution). These nonpolar compounds are called hydrophobic (hydro- = 'water'; -phobic = 'fearing').