Discuss the Atomic Structure and its components

According to the modern theory, matter is electrical in nature. All the materials are composed of very small particles called atoms. The atoms are the building bricks of all matter. An atom consists of a central nucleus of positive charge around which small negatively charged particles, called electrons revolve in different paths or orbits.
(1) Nucleus: It is the central part of an atom and contains protons and neutrons. A proton is a positively charged particle, while the neutron has the same mass as the proton, but has no charge. Therefore, the nucleus of an atom is positively charged. The sum of protons and neutrons constitutes the entire weight of an atom and is called atomic weight. It is because the particles in the extra nucleus (i.e. electrons) have negligible weight as compared to protons or neutrons.
? Atomic weight = no. of protons + no. of neutrons

(2) Extra nucleus: It is the outer part of an atom and contains electrons only. An electron is a negatively charged particle having negligible mass. The charge on an electron is equal but opposite to that on a proton. Also, the number of electrons is equal to the number of protons in an atom under ordinary conditions. Therefore, an atom is neutral as a whole. The number of electrons or protons in an atom is called atomic number i.e. atomic number = no. of protons or electrons in an atom
The electrons in an atom revolve around the nucleus in different orbits or paths. The number and arrangement of electrons in any orbit is determined by the following rules:
i. The number of electrons in any orbit is given by 2n² where n is the number of the orbit. For example,
a) First orbit contains 2 × 1² = 2 electrons
b) Second orbit contains 2 × 2² = 8 electrons
c) Third orbit contains 2 × 3² = 18 electrons and so on.
ii. The last orbit cannot have more than 8 electrons.
iii. The last but one orbit cannot have more than 18 electrons.
NB
1. The difference between various types of elements is due to the different number and arrangement of
these particles within their atoms.
2. The atomic structure can be easily built up if we know the atomic weight and atomic number of the
element.

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Wilfykil answered the question on August 13, 2019 at 09:55