Question

What are the differences between atoms and molecules?

Answer 1

Hint: The universe is made up of atoms, which contain protons, neutrons and electrons. Molecules are formed when two or more atoms bond together. Atoms can bond together into groups and form a molecule.

Complete answer:
Let us understand what an atom is:

Atoms are the smallest units of matter and they are the defining structure of an element. Atoms are made up of three particles: protons, neutrons and electrons which are composed of even smaller particles, such as quarks. Protons and neutrons are heavier than electrons and reside in the nucleus at the centre of the atom. Electrons are extremely lightweight and exist in a cloud orbiting the nucleus. Protons and neutrons have approximately the same mass.

Now, let us know about molecules.
A molecule is defined as two or more atoms of the same element or different elements that are bound together. Molecules are of two types, homonuclear and heteronuclear. Homonuclears are those which consist of atoms of one chemical element, as with oxygen. Whereas, Heteronuclears are those where a chemical compound composed of more than one element, as with water.

Let us differentiate between atoms and molecules!
Atoms:
The constituent elements in atoms are protons, electrons and neutrons.
The stability may not always be stable in nature due to the presence of electrons in the outer shells.
The structure of an atom, it's the smallest particle with properties of an element.
Examples are: oxygen, phosphorus, sulphur and hydrogen.

Molecules:
The constituent elements are two are more atoms of the same or different elements.
Molecules are formy to attain stability.
The structure is formed to attain stability.
Examples: Oxygen-$O_2$, phosphorus-$P_4$, sulphur-$S_8$ etc.

Note: Remember that atoms do not multiply, some atoms are radioactive and decay into other atoms. Some atoms emit alpha particles when they decay. If molecules contain atoms of different elements, that substance is known as a compound.