What do you understand by the following
An atom is defined as the basic unit of element which possesses the properties of the element. By basic, we mean that it is the building block of matter . It is the smallest particle of an element that can take part in a chemical reaction. Every atom consists of protons, neutrons and electrons. For example Carbon will consist of atoms which will show the properties of carbon only and not any other element.
A molecule on the other hand is a group of two or more atoms formed when these atoms chemically combine with each other. These atoms may either be of same of or different elements. For example, 2 atoms of Hydrogen and one atom of oxygen combine to form one molecule of water. Similarly, 2 hydrogen atoms combine with each other to form a molecule of hydrogen.