- Chemical Reactions
In this demonstration, students will observe interactions between polystyrene, water and acetone and explain the results in terms of their molecular structure.
Molecules with evenly distributed electrons are nonpolar and molecules that have an uneven electron distribution are polar. A common saying in chemistry is “Like dissolves like.” In other words, polar molecules can dissolve polar molecules and nonpolar molecules can dissolve nonpolar molecules. A mixture of polar and nonpolar molecules will remain separate unless special molecules with qualities of both are present to help them mix together.
Chemists categorize molecules in a variety of different ways. Organic molecules always contain carbon and hydrogen and may contain other elements such as nitrogen, oxygen, phosphorous and sulphur. They are often found in living systems but could also be synthesized in a laboratory. Some organic molecules are very large. Knowing that a molecule is organic does not help chemists to predict how it will react, but does influence the way these molecules are named and studied.
Some of the largest organic molecules are polymers. Polymers are long chains or webs made of smaller groups of atoms called monomers that are joined together like beads on a string. Common examples of polymers include DNA, proteins, nylon and Silly Putty. Chemical reactions can attach monomers together into polymers and can also break them down again.