Energy produced when atoms split or when atoms join to form one atom?

Answer 1

This is just called nuclear energy (or Atomic energy).

Yes a beautiful phenomenon!

When lighter nuclei combine together heat energy is evolved along with some radiations. This is known as nuclear fusion. Very good example is the sun and stars where energy is produced only by this phenomenon
When a heavier nuclei split into lighter ones, once again heat is produced along with some kind of radiations. This is known as nuclear fission. Good example is the nuclear reactor where lot of heat energy is produced which in turn gets used to produce electricity.

The secret in nature goes this way. The simplest atom is the hydrogen where we have the lowest number ie one proton and one electron in its surrounding orbits.
According to Einstein, mass has come out of energy. So let us assume this hydrogen as one energy ball. When such four energy balls get combined together, certain amount of energy is given out in the form heat and other radiations and new ball named helium is formed.

There by, the mass of the product produced, namely helium, will be found less than the expected mass of the constituents ie two protons and two neutrons in the nucleus of the helium.

This is termed as Mass Defect. We use a convenient unit of mass in this situation instead the SI unit, kilogram. That convenient unit is Atomic Mass unit. Simply amu.
Same way eV is a convenient unit for energy instead joule.

In physics, the equivalent energy to this mass defect is named as binding energy (BE). It means that the energy already come out during binding process. Binding energy of a nucleus is divided by the number of nucleons in the nucleus. This is said to be binding energy per nucleon (BE/A), an important detail which would explain the secret of emission of heat energy during fission process.

Let us note the salient point that higher the BE/A more energy would be given out while forming such nuclei.

As we plot the BE/A with A in a graph, BE/A is found to be maximum (8.8MeV) for iron (A=56). So iron is the most stable element. (We call those, who is very stubborn, as a person with iron heart) This BE/A is found to be very low (2 M eV) for hydrogen, helium etc. (A slightly more than1). Same way it is comparatively lower (7.7MeV) for higher nuclei such as uranium, thorium etc. (A = round about 230 and above)
Thus when hydrogen get fused to form helium its BE/A increases.

When such uranium nuclei get split, it gives out some elements with lower A (barium, krypton). So elements with higher BE/A is formed. In turn, we easily understand that more energy would be given out. So, when heavier nuclei get split, enormous energy is liberated. This is how nature with its intelligence plays this dramatic behaviour.

The same intelligence, inherent in human, finds out this secret and has started to use that nuclear power positively in generating electricity. Unfortunately, misused by the same human brain, in the form of atom bomb exploded at Hiroshima. The problem is, along with heat energy some radiations such as alpha, beta and gamma rays are produced which are harmful.

The most advantage in nuclear fusion is that it gives harmless radiation but the pity is to start such nuclear fusion enormous energy is needed. That is "starting trouble".
If we find a good technique to keep fusion going on in a convenient way, then power crisis would come to an end, once for all.

Answer 2

Nuclear energy is derived from two processes, fusion and fission.

Fission Energy is produced when the nucleus of an atom splits apart.

Fusion Energy is obtained when nuclei of atoms join to form one atom.

Fission is for larger nuclei, larger than iron.

Fusion is for small nuclei.

Fusion happens in the sun.

Fission happens in a nuclear reactor.

The energy source in both cases is energy from the nuclei of the atoms involved.

That energy emerges in the form of light and heat.

It can be said that humans use nuclear energy to produce electrical energy.

Humans know how to do fusion as well, but that has not been accomplished very efficiently so it is not used to make electricity.
Energy is not produced during fission or fusion. It is released. The energy is binding energy.

Answer 3

Nuclear energy is derived from two processes, fusion and fission.

Fission Energy is produced when the nucleus of an atom splits apart.

Fusion Energy is obtained when nuclei of atoms join to form one atom.

Fission is for larger nuclei, larger than iron.

Fusion is for small nuclei.

Fusion happens in the sun.

Fission happens in a nuclear reactor.

The energy source in both cases is energy from the nuclei of the atoms involved.

That energy emerges in the form of light and heat.

It can be said that humans use nuclear energy to produce electrical energy.

Humans know how to do fusion as well, but that has not been accomplished very efficiently so it is not used to make electricity.

Answer 4

1. nuclear fission energy
2. nuclear fusion energy