Energy is all around us. Energy can be classified as potential or kinetic. Potential energy is stored energy. Kinetic energy is moving energy. There are many types of potential and kinetic energies. Chemical energy is a type of potential energy because it is the energy stored in atoms and molecules.
Atoms are the basic units of matter. An atom is made up of a nucleus surrounded by electrons. Hydrogen is the simplest atom in the universe. It has one positively charged proton in its nucleus and one negatively charged electron orbiting the nucleus. Other atoms have more protons and electrons.
Molecules form when different atoms join together. Water is a molecule made up of two hydrogen atoms and one oxygen atoms. That’s why we sometimes call water H2O.
Every atom has energy. When one atom combines with other atoms to form a molecule, energy is released. It is easier for atoms to be a part of a molecule than it is to be an individual atom, so atoms release energy when they form bonds.
On the other hand, it is difficult to break bonds between atoms. Energy must be added to the molecule to break the bonds and release the atoms. Water doesn’t randomly break apart into hydrogen and oxygen atoms because it takes energy to break the bonds. If it didn't, swimming would be crazy!
We use the chemical energy released from food when we eat. Digestion breaks the food into small units called fatty acids, amino acids, and glucose. These molecules are sent to our cells to be converted from chemical energy to mechanical energy and heat. For example, it takes energy to break the bonds in a glucose molecule, but when the atoms from the glucose molecule reform into water and carbon dioxide molecules a lot of energy is released. Our cells use this energy to do their jobs.
Chemical energy is also stored in coal and oil. Power plants turn this chemical energy into electrical energy that we use in our homes and businesses. Coal and oil are both nonrenewable resources, so they cannot be easily replaced once they have been used. That is because it took the coal and oil millions of years to form.
Millions of years ago, when plants and animals died, they were left on the ground. Over time, dirt, mud, and rocks covered them. Eventually, this dirt and rock became solid rock. The surrounding rock pressed on the remains of the plants and animals turning them into coal or oil. Trees, ferns, and other plants became coal, and bacteria, algae, and plankton became oil.
Coal and oil are still forming today, but we are using these resources faster than the Earth can replace them. This is why they are called nonrenewable resources. Scientists expect Earth to run out of oil within the next hundred years.
Other sources of chemical energy include wood, batteries, and explosives. When wood burns, chemical energy is converted into the heat and light energy of fire. Batteries store chemical energy that can be converted into electrical energy to make electronics work. When explosives, such as fireworks, are detonated, their chemical energy becomes heat, sound, and light energy.
Chemical energy is a part of our everyday lives. From the food we eat to the gasoline in our cars, we couldn’t live without chemical energy.