THE SUN: Fusion, Fission and Combustion Earth & Environmental Science THE SUN: Fusion, Fission and Combustion
Definitions Fusion- Combining of nuclei Fission- Splitting of a nucleus Combustion- Chemical reaction in which an atom combines with oxygen
What is the Fuel? Fusion Fission Combustion Uses small, light atoms like Hydrogen Fission Uses large, heavy atoms like Uranium Combustion Uses any substance that will react with Oxygen
How Does it Start? Fusion Fission Combustion Requires great heat and pressure Fission Starts when a neutron strikes the nucleus and causes it to split. More neutrons are released causing a chain reaction. Combustion Requires small amount of energy to activate the reaction.
What is Released and/or Converted? Fusion Releases large amounts of energy. Mass is converted to energy. Fission Combustion Releases smaller amounts of energy that are present in the bonds between atoms. Reactants start at a higher energy level than products.
How Long does the Reaction Last? Fusion Does not explode because there is no chain reaction Fission Can explode because of chain reaction Combustion Once started, heat from combustion will keep the reaction going as long as the reactants are present.
Where does it Happen? Fusion Fission Combustion Happens in core of a star. Can happen briefly in a laboratory. Happens in a hydrogen bomb. Fission Happens in nuclear power plants. Happens in an atomic bomb. Combustion Happens any time there is a fire. Can also happen slowly as in the case of something rusting.