Atomic Number: Atomic number of an element is equal to the number of protons present in the nucleus of an element. Atomic number = number of protons in one atom of element. Since the atom as a whole is neutral therefore atomic number is the same as the number of electrons around the nucleus of
The law of Conservation of Mass states that the mass of matter before and after a chemical change remains the same. The number of atoms also remains the same. The only thing that changes is the arrangement of the atoms. For example, the mass of hydrogen and oxygen before they combine to make water is