Target ESE 2022 (Basics of Material Science & Engineering)

 👉Atoms are made of electron, proton and neutrons. 

👉 Electrons and protons are negative and positive charged particles respectively. The magnitude of each charged particle in an atom is 1.6 x 10^-19 Coulombs.

👉The mass of electron is negligible as compare to proton and neutron.

👉The unit of mass is an atomic mass unit

          1 a.m.u = 1.66 x 10^-27 kg 

👉Matter is composed of tiny particles called atoms.

   1. Stable particles: Electron, proton and neutron

   2. Unstable particles- positron, neutrino, anti-neutrino and meson

   3. Composite particles- Deuteron and alpha- particles

👉Electron: It carries a very small negative electrical charge.

                      It has negligible mass i.e. its mass is 1/850th of the mass of hydrogen atom.

👉Proton: It carries small positive electrical charge. 

                   Mass of each proton is same as that of hydrogen atom.

                   Protons are also present in all all the atoms.

 👉Neutron: It does not carry any electrical charge. Its mass is equivalent to that of proton.

👉 Positron or positive electron: The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has an electric charge of +1 e

👉Meson: The mass of meson is in between the mass of electron and proton.

                   Mesons were discovered during cosmic ray studies.

👉 There are two types of meson (i) p-meson which is heavier (ii) m-meson which is light

👉Both type of mesons may be either negatively or positively charged.

👉Deuteron: It is positively charged.

                      It is heavy hydrogen nucleus.

 👉 Alpha Particles: They are double charged helium nucleus.

                                    They appear as product of radioactive decay.

👉Meson carries a either negative or positive charged.

👉The weight of an electron is 1/1836 of the weight of proton or neutron.

👉Avogadro Number(N) = 6.023 x 10^23

👉Mean distance between atoms in the range of 0.23 nm.

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