Why are heavy elements better for nuclear fission?

The fission of heavy elements is an exothermic reaction, and huge amounts of energy are released in the process. Nuclear fission occurs with heavier elements, where the electromagnetic force pushing the nucleus apart dominates the strong nuclear force holding it together.

Can a neutron be knocked out of a nucleus?

You know that neutrons are found in the nucleus of an atom. Under normal conditions, protons and neutrons stick together in the nucleus. During radioactive decay, they may be knocked out of there.

Why is a heavy nucleus unstable?

In heavy nuclei, the Coulomb energy of proton repulsion becomes very significant and this makes the nuclei unstable. It turns out that it is energetically more profitable for a nucleus to throw out a stable system of four particles, i.e., an alpha particle, than individual nucleons.

What happens to the nucleus when it gets too heavy?

When a heavy nucleus absorbs a neutron, it will split into two or more fragments with the ejection of several high-energy, high-velocity (fast) neutrons in the fission process. The only naturally occurring isotope that can fission with the absorption of a slow, low energy (thermal) neutron is U-235.

Why is neutron used in nuclear fission?

In a critical fission reactor, neutrons produced by fission of fuel atoms are used to induce yet more fissions, to sustain a controllable amount of energy release.

What is the role of a neutron in nuclear fission?

These neutrons can induce fission in a nearby nucleus of fissionable material and release more neutrons that can repeat the sequence, causing a chain reaction in which a large number of nuclei undergo fission and an enormous amount of energy is released. …

What is the difference between a stable and unstable nucleus?

An atom is stable if the forces among the particles that makeup the nucleus are balanced. An atom is unstable (radioactive) if these forces are unbalanced; if the nucleus has an excess of internal energy. Instability of an atom’s nucleus may result from an excess of either neutrons or protons.

Why do heavier elements require more neutrons to maintain stability?

The reason is that protons, being charged particles, repel each other. As you get to heavier elements, with each new proton you add, there is a larger repulsive force. So you need to add extra neutrons, which do not repel each other, to add extra attractive force.

What is addition of neutron to form heavier nuclei?

If neutrons are added to a stable nucleus, it is not long before the product nucleus becomes unstable and the neutron is converted into a proton. Outside a nucleus, a neutron decays into a proton and an electron by a process called beta decay (β-decay).

Why do we get more neutrons than protons in a nucleus?

As the nuclei get larger, the neutron well gets deeper as compared to the proton well and you get more neutrons than protons.

Why do heavier elements have more protons than lighter elements?

The reason is that protons, being charged particles, repel each other. As you get to heavier elements, with each new proton you add, there is a larger repulsive force. The nuclear force is attractive and stronger than the electrostatic force, but it has a finite range. So you need to add extra neutrons, which do not repel each other,…

Why is the nuclear force stronger than the electrostatic force?

The reason is that protons, being charged particles, repel each other. As you get to heavier elements, with each new proton you add, there is a larger repulsive force. The nuclear force is attractive and stronger than the electrostatic force, but it has a finite range.

What happens to heavy nuclei formed by fusion reactions?

Heavy nuclei formed by fusion reactions often decay rapidly by fissioning into two fragments. Protons and neutrons form shell structures in a nucleus similar in some ways to those observed in the filling of electron energy levels in an atom; in particular, as shells fill up and become closed,…