Question

what is atom
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Answer 1

Smallest part of an element that part in a chemical reaction

Answer 2

an ATOM is the smallest particle of a thing which can take part in a chemical reaction.
An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms.
it has electrons that has a negative charge,protons containing positive charge and neutrons containing neural i.e,no charge.
here's is an image for u to understand a structure of atom.