Size of the Nucleus

Introduction

An atom is the smallest unit of any substance, and it is the building block of chemistry. The centre of an atom contains positively charged protons and neutral neutrons, which occupy the vast majority of the atom’s interior space. The nucleus of an atom is made up of protons and neutrons. The electron cloud that surrounds the nucleus is made up of negatively charged particles. 

History of Nucleus and the Electron

The Latin term “nucleus” is another word for “nux” (it means kernel or nut) (it means kernel or nut) and is used to refer to the nucleus (it means kernel or nut). Michael Faraday invented it in 1844 to define the centre of an atom. Physicists in nuclear physics and nuclear chemistry focus on the nucleus’s structure and properties.

J.J.Thompson carried out his cathode ray tubes experiment and discovered that all atoms contain electrons. In Thompson’s “Plum pudding model”, an atom included a positively charged “soup” including negatively charged electrons.

Using Rutherford’s gold foil experiment, scientists determined that most of an atom’s nucleus is empty.

Nucleus

• Protons and neutrons in the nucleus are held together by a strong electric force.
• Since it contains a positive proton, the nucleus’s electrons are drawn to it, yet they move so quickly that they either circle it or fall around it.
• Protons in the nucleus are responsible for their positive charge.
• In a nucleus, protons and neutrons are heavier than electrons; hence the nucleus takes up most of the mass.
• The number of protons in a nucleus identifies an atom as belonging to a certain element.
• The number of neutrons in a nucleus defines which isotope of an element it is.

Experiment with gold foil conducted by Rutherford

Ernest Rutherford’s nucleus concept was eventually acknowledged as the proper nuclear model, notwithstanding J.J. Thompson’s first proposal. After the Rutherford Gold Foil Experiment, the final model was provided. A significant question for Rutherford was the arrangement of electrons inside an atom. As a means of doing this, he chose to conduct an experiment in which he had fast-moving particles (alpha particles) fall on gold foil.

Alpha particles, which have a mass of 4 and a tremendous amount of energy, are helium ions (doubly charged). Because he wanted a very thin coating, he used gold foil. This gold foil was around 1000 atoms thick. As the subatomic particles of gold atoms are heavier than protons, he expected them to deflect very little. However, the outcomes of this experiment were completely unexpected.

Size of the Nucleus

The atomic nucleus is a compact, dense area at the centre of an atom made up of protons and neutrons that was discovered in 1911 by Ernest Rutherford based on the Geiger–Marsden gold foil experiment of 1909. Dmitri Ivanenko[1] and Werner Heisenberg created models for a nucleus made up of protons and neutrons soon after the neutron was discovered in 1932. A positively charged nucleus is surrounded by a cloud of negatively charged electrons that are held together by electrostatic force. The nucleus contains almost all of an atom’s mass, with the electron cloud contributing just a little amount. The nuclear force binds protons and neutrons together to create a nucleus.

Rutherford’s observations

• There was no deflection in the big chunk of fast-moving alpha particles that went through the gold foil.
• Some of the alpha particles were deflected by modest angles.
• It was the most astonishing finding when a few alpha particles completely rebounded. Rebounding was detected in at least one of every 12,000 particles.

Rutherford experiment conclusions

• An empty area has been left because most of its electrons have travelled through the gold foil.
• Due to the small number of deflected particles, it was assumed that the atom’s charge was relatively small.
• The gold foil’s positive charge atom was concentrated in a tiny volume inside the atom due to the total bouncing off of a few particles from the foil.

Rutherford’s nuclear model

Rutherford came up with the following nuclear model for an atom based on his experiments.

• The nucleus, which occupies almost all of an atom’s mass, is positively charged at the centre.
• The nucleus’s electron orbits are well-defined.
• According to the relative size of the individual elements in an atom, nuclei are very tiny in proportion to their surroundings.

Atomic Quantum Factor

Charges of similar size, both negative and positive, cancel each other out. This indicates that the electron’s negative charge cancels out the proton’s positive charge exactly. There must be precisely one electron for every proton in a neutral atom. If an atom contains one proton, it must also have one electron. There must be two electrons in a neutral atom if there are two protons in it. If an atom contains 10 protons and 10 electrons, it is neutral. 

Conclusion

We’ve seen that the smallest unit of matter is an atom, which has chemical element qualities and is the fundamental building block of chemistry. The majority of an atom’s interior is empty space, with protons (positively charged particles) and neutrons (neutral particles) at the centre. The nucleus of the atom is made up of protons and neutrons. The nucleus is surrounded by electrons, which are negatively charged particles that form a cloud around it.

To differentiate an atom of one element and another, one should pay attention to the number of protons in its nucleus. One of the most critical properties of atoms is their ability to be uniquely identified by their atomic number. Carbon, for example, has the atomic number 12 and contains 12 protons in its nucleus while Hydrogen atom has only one proton.