Atomic nucleus


An atomic nucleus is the center of an atom, made up of protons and neutrons. These are together known as nucleons. The protons and neutrons in a nucleus are held together by the nuclear force, which is a remnant of the strongest fundamental force in nature, the strong interaction. The nucleus makes up most of the mass of the atom.

Frequently Asked Questionsedit

Why electrons don’t fall into the nucleus due to attraction?edit

Electrons tend to stay away from the nucleus because it would violate the uncertainty principle. If the electron is confined inside a space as small as the nucleus, then its position and momentum could be determined, which is impossible. So that doesn’t actually happen when you try to confine an electron inside a nucleus. According to the uncertainty principle, the energy of the electron will increase as it moves closer to the nucleus. This increases the momentum uncertainty and tends to push the electron away from the nucleus, battling the electrostatic force. The point at which these two cancels out each other will be the electron’s stable configuration in an atom. But there is a special type of decay called as the beta plus decay, where a proton-rich nucleus would absorb an electron to decay itself into a neutron by emitting a positron and a neutrino.

What happens when you split the atomic nucleus?edit

Nuclear fission happens. When the atomic nucleus is split, a tremendous amount of energy is released, forming two lighter nuclei in the process. A well-known example of a fissile element is uranium 235U, which when bombarded with neutrons split into two lighter nuclei. The total mass before splitting is higher than that of the combined mass of the two nuclei and any neutrons emitted. This difference is mass will be the energy of the fission reaction, and it will be enormous. When the emitted neutrons are made to bombard more 235U nuclei, there will be a chain reaction that keeps on splitting more 235U nuclei, exponentially releasing immense amounts of energy.

How could the atomic radius of the atomic nucleus be defined?edit

The density of the atomic nucleus is usually concentrated towards the centre where the nucleons exist. An approximate radius of that dense region can be found by using the formula - R = R0A1/3, where R0 is 1.2 fm, and A is the atomic mass number. Some specific cases like the halo nucleus of lithium, the radius of the nucleus will be higher, and hence this formula fails. In such cases experimental methods like x-ray spectroscopy are used.