Subatomic Scale

The ‘structure of a substance’ has been a fascinating question for scientists for many decades. Firstly, scientists all over the world believed that molecules are the smallest unit of matter. Gradually, they evolved their research and established a new theory that says the atom is the smallest unit of matter. Many atoms together form a molecule. Atoms are made of electrons, protons and neutrons. These subatomic particles are made of some smaller particles known as quarks. Research is still going on but for now, we agree on the fact that atoms are made of electrons, protons and neutrons and they are the subatomic particles.

An atom is the smallest unit of a matter. Atomic structure consists of three particles- neutron, proton and electron. Ernest Rutherford discovered the nucleus. Nucleus is the core matter of an atom which consists of protons and electrons. Proton is a positively charged particle and neutron is a particle which has zero charge on it. Both particles are present in the nucleus, that’s why the nucleus is positively charged. Neutrons and protons together are called the ‘nucleon’.

Subatomic particles in an atom-

An atom has a nucleus which has positive charge on it and electrons revolve around the nucleus, this combination makes the atom neutral. The number of protons inside the nucleus is equal to the number of electrons revolving around the nucleus. The atomic number which is represented by ‘Z’ is actually the number of protons or the number of electrons of the atom. For atomic mass also, we count the mass of protons and neutrons. The atomic structure depends upon the fundamental particles only.

We denote the fundamental charge by ‘e’ which cannot be written in fractional form. It is always a whole number, like – 1e, +2e or ‘-3e’ etc. It is the smallest charge which has the value of 1.6 ×10-19 coulomb. Now, a proton has the charge ‘+e’ and an electron has the charge ‘-e’. Neutron has a zero charge. Inside the nucleus, neutrons balance the repulsive forces which are exerted by all protons on one another. The presence of neutrons inside the nucleus actually makes the atomic structure stable, otherwise the atom will collapse by the repulsion force of protons.

Electrons are present in the outermost shell of the atom and they are responsible for all the reactions and bonds that an atom makes. The outermost shell of the atom is known as the ‘valence shell’. The atoms present in the outermost shell are loosely bound, so they get connected or separated easily at the ‘excited state’ of the atom. An electron deficient matter gains the electrons and an electron rich atom loses its electron in the reaction.

Mass of a proton is 1.6 ×10-27 kg, mass of an proton is 1.6 ×10-27 and mass of an electron is 9.1 ×10-31kg which clearly indicates that the electron is the lightest subatomic particle among them. These subatomic particles, protons and neutrons are again made of some small groups called quarks. These are very small charges of different types which bind up to make these fundamental particles.

To measure the size of a particle which is smaller than an atom, we use the subatomic scale that calculates the size of a particle.

Size of an atom is 10-10m, size of nucleus is 10-14m, size of quarks goes in range of 10-16 or 10-17m. Thus, we compare the size of particles by comparing it with the size of atoms.

Conclusion

Atomic structure has three fundamental particles called proton, electron and neutron. An electron is a negatively charged particle, a proton is a positively charged particle whereas a neutron has zero charge. Protons are present in the nucleus with their excessive repulsive force which is balanced by neutrons to make the atom stable. Electrons revolve around the nucleus and this mechanism keeps the atom neutral unless the atom gets excited and loses or gains some of its electrons.