Suppose by some means, we coulde divide an elements such as iron into smaller and smaller particles. We would finally get the smallest particle of iron, which still has the properties of iron If the particle were further divided, it would lose the properties of iron. This particle is the atom of the element.
The smallest particle of an element that retains the properties of the element is called an atom.
An atom is so small that it is not possible to see it, even with a powerful microscope. It is even difficult to imagine something as small as an atom. Each element has its own kind of atom.
An element is made up of only one kind of atoms. All atoms of an element are identical. For example they have the same size and mass. But atoms of one element are different from the atoms of another element. All atoms of gold are identical, and all atoms of iron are identical, but atoms of gold are different from the atoms of iron. For example, atoms of gold are bigger and heavier than atoms of iron.
There are more than 100 different types of atoms-equal to the number of elements.