Stable and Unstable Nuclei

The Strong Nuclear Force binds Nucleons together

The Strong Nuclear Force (also referred to as the strong force) is one of the four basic forces in nature (the others being gravity, the electromagnetic force, and the weak nuclear force). As its name implies, it is the strongest of the four.

However, it also has the shortest range, meaning that particles must be extremely close before its effects are felt. Its main job is to hold together the subatomic particles of the nucleus (protons, which carry a positive charge, and neutrons, which carry no charge. These particles are collectively called nucleons). As most people learn in their science education, like charges repel (+ +, or - -), and unlike charges attract (+ -).

If you consider that the nucleus of all atoms except hydrogen contain more than one proton, and each proton carries a positive charge, then why would the nuclei of these atoms stay together? The protons must feel a repulsive force from the other neighboring protons. This is where the strong nuclear force comes in. The strong nuclear force is created between nucleons by the exchange of particles called mesons. This exchange can be likened to constantly hitting a ping-pong ball or a tennis ball back and forth between two people. As long as this meson exchange can happen, the strong force is able to hold the participating nucleons together.

         

Alpha Emission Happens in Very Big Nuclei

1. Alpha emissions only happens in very big atoms (with more than 82 protons), like uranium and radium.
2. The nuclei of these atoms are just too big for the strong nuclear force to keep them stable.
3. When an alpha particle is emitted: the Proton number decreases by two, and the nucleon number decreases by four.

Beta Emissions Happens in Neutron-Rich Nuclei

1. Beta-minus decay is the emission of an electron from the nucleus along with an antineutrino.
2. Beta decay happens in "neutron rich" isotopes.
3. When a nucleus emits a beta particle, one of the neutrons in the nucleus is changed into a proton.

• Proton number increases by one, and the nucleon number stays the same.