How many electrons are on each energy level?
Energy is used to do work. In our modern lives we are more and more preoccupied with finding new sources of energy to heat our buildings and move our machines, including cars. Since the dawn of the 20th century, fossil fuels have been the main way we get energy, but those forms of energy are causing environmental damage and leading to global warming. That is because the burning of fossil fuels releases carbon dioxide into the atmosphere. New forms of energy are being sought.
