Question

The ________ of an atom is very hard and dense.

Answer 1

Hint: We know that each substance of earth is made up of its constituting atoms. The atoms are polymerised to form the bulk elements.

Complete step by step answer:
In order to know about the hard and dense part of the atom, we will study about the structure of atoms.
Atom of an element is its basic component of an element and has electrons, protons and neutrons in its structure. The electrons are present in the shells surrounding the nucleus and protons and neutrons are present in the nucleus of the atom.
Electrons: They are negatively charged ions present in the shells of an atom.
Mass of an electron is fixed which is $9.01 \times {10^{ - 31}}{\text{kilogram}}$.
Protons: They are positively charged ions present in the nucleus of the atom.
Neutrons: They are the neutral species present along the protons in the nucleus of an atom.
The charge of nucleus is due to presence of protons and contribution of neutrons is nil to the charge of nucleus, but the mass of both neutron and proton is quite similar which is $1.67 \times {10^{ - 24}} gram$.
The mass of neutrons combined with the mass of protons, gives nucleus its density and hardness and the mass of electrons is negligible in comparison to nucleus mass.
Thus, the nucleus is a hard and dense part of the atom.


Note:
The arrangement of electrons around the nucleus follows a pattern in shells of an atom which is known as electronic configuration of the atom. The series is as follows: \[1s,{\text{ }}2s,{\text{ }}2p,{\text{ }}3s,{\text{ }}3p,{\text{ }}4s,{\text{ }}3d,{\text{ }}4p,{\text{ }}5s,{\text{ }}4d,{\text{ }}5p,{\text{ }}6s,{\text{ }}4f,{\text{ }}5d,{\text{ }}6p,{\text{ }}7s,{\text{ }}5f,{\text{ }}6d\]. The arrangement of electrons gives the atom its property which makes it unique in the periodic table.