b) Binding energy

• the changes in mass and energy when a nucleus is divided into its nucleons

• work is done to overcome the strong nuclear force

• energy is transferred to the nucleus

• the nucleus gains rest mass

• it separates

• the rest mass of the nucleons > the rest mass of the nucleus

• mass defect

• the difference between

• the rest mass of a nucleus

• and the rest mass of the nucleons

• binding energy

• the minimum energy required to separate a nucleus

• the formula for the binding energy of a nucleus

• binding energy (J) = mass defect (kg) × speed of light2 (m2s-2)

• the relationship between nuclear stability and the binding energy per nucleon

• the stability of a nucleus is proportional to the binding energy per nucleon

• a graph of binding energy per nucleon against nucleon number

• the most stable element is…

• iron

• iron has a nucleon number of…

• 56

• an atom with a low nucleon number below 56 is more likely to undergo…

• fusion

• an atom with a low nucleon number below 56 is more likely to undergo fusion because…

• it has a low binding energy per nucleon

• fusion increases its binding energy per nucleon

• which makes the nucleus more stable

• an atom with a very high nucleon number above 56 is more likely to undergo…

• fission

• an atom with a very high nucleon number above 56 is more likely to undergo fission because…

• it increases its binding energy per nucleon

• which makes the nucleus more stable