Do you do chemistry? If so, compare it to bonding in compounds; the stronger they are (eg. ionic bonds stronger than covalent) the more energy you need to use to break them apart (decompose the compound).
Or if you don't, think of it as; the binding energy is 'used' (not sure how) to hold the nucleus together. If you want to break something apart, you need to input energy. Say a nucleus is a brick wall, and you want to break it apart with a sledgehammer (nuclear reaction). If there is lots of mortar between the bricks, you'll need to hit the wall hard, ie. input a lot of energy, to break the wall apart. If there were no mortar between them, you could hit it lightly, ie. input less energy, and the wall would break apart.
Stable-ness in a nucleus is its resistance to breaking apart apart by radioactive decay, (eg. big nuclei are unstable). The more binding energy each nucleon has, the harder it is to break up the nucleus, therefore it is more stable.
Sticking to the syllabus,
· Explain the concept of a mass defect using Einstein’s equivalence between mass and energy
The masses of atoms can be measured using a mass spectrograph. When doing this, it can be found that the mass of the atoms is less than the sum of the masses of all its components (protons, neutrons and electrons). This difference is called mass defect. Binding energy is the energy required to separate the atom into its separate parts. Using Einstein’s equivalency between mass and energy, it can be seen that the mass defect is converted into the binding energy of the nucleus. The binding energy is given by E = ∆mc2, where ∆m is the mass defect. Dividing the binding energy of a nucleus by the amount of nucleons, the average binding energy per nucleus is given. This is an indication of the stability of the
nucleus, the higher it is, the more stable.
