Water is formed when energy causes hydrogen and oxygen molecules to fit together. The process of creating water is very turbulent, making it very difficult for scientists to safely create water in a laboratory.
Water has very simple properties; it contains one oxygen atom and two hydrogen atoms, which are held together by electrons. A water molecule resembles a magnet in that its oxygen atom has a negative charge and the hydrogen atoms have a positive charge. These positive and negative charges cause the atoms to pull on each other, creating a natural polarity that enables water molecules to stick together.
When water is frozen, it becomes crystallized and forms ice. Water's unusual property of being denser in liquid form than in solid form causes ice to float on liquid water. Water is a universal solvent because most substances dissolve in it. Substances that dissolve easily in water are called hydrophilic substances, and those that do not dissolve well in water are known as hydrophobic. Because water can dissolve more substances than any other solvent, it is rarely pure and usually contains minerals such as magnesium and calcium. Even when water is treated for domestic use, these minerals are often left behind, leading to what is known as hard water.