Styrofoam works well as an insulator because it mostly consists of air confined to small pockets. These pockets hinder the convection process from carrying heat energy away from (or to) the substance inside the container.
Three different processes allow heat energy to flow: radiation, convection and conduction. Of these, conduction and convection are the two processes relevant to the use of Styrofoam. Conduction involves the flow of heat energy from a hotter object to a colder one. For example, a person picking up an ice cube notices that the ice cube melts in his hand as heat conducts from his hand to the cube. Convection involves a series of currents that emerge when a gas or liquid flows from a warmer place to a cooler one, or vice versa.
Styrofoam is a poor conductor, and the air pockets trapped inside the material keep heat energy from leaving. This is why Styrofoam products are popular for holding hot things like cups of coffee. The material does not conduct the heat from the beverage through to the hand in the same way that a metal or glass cup might. However, the trapped air pockets limit convection of the heat away from the beverage, and so beverages stay hot for longer in Styrofoam.Learn More
Metals are good conductors of electricity because their atoms contain at least one free electron. They are also considered excellent heat conductors, because the metal ions in the lattice are closely packed together, and the delocalized electrons can bring kinetic energy through the lattice.Full Answer >
According to HowStuffWorks, aluminum foil is a good insulator because it prevents the radiation of heat by reflecting it back at the source. Since aluminum foil reflects the emission of heat, it tends to be a better insulator than other materials that just slow down the flow of heat from one area to another.Full Answer >
Copper conducts heat well because its atoms contain only one free valence electrons in the outer shell. Elements with a low number of valence electrons transfer heat the best, and copper has only one.Full Answer >
Many metals, like silver, copper, gold and aluminum, are good thermal conductors. Thermal conductors are materials that heat passes through easily. Conduction, or the transfer of heat, can take place within a single material or between two objects.Full Answer >