Protons, electrons and neutrons are the major constituents of an atom. There are thousands of varieties of atoms and each has different sets of those above-mentioned particles, the number of constituents is what defines them.
Find Number of Protons, Electrons and Neutrons
Number of Protons
Protons are positive charge carriers, each has positive 1.6*10^-19 coulomb charge and mass 1.673*10^-24 grams. The number of protons in an atom also called atomic number is different for different elements, the same element has the same number of protons in their atoms.
It is represented by Z. Whenever someone says carbon, you can precisely say that it has 6 protons, this is why it is called carbon. Or, an element with 6 protons in their atoms is called carbon.
Same follows for hydrogen or oxygen or nickel or copper with 1 or 8 or 28 or 29 protons respectively. They have a number of protons which defines what element are they. Also, it defines the chemical and physical properties of an atom.
Number of Electrons
Electrons are negative charge carriers, each has negative 1.6*10^-19 coulomb charge and mass 9.1*10^-28 grams. The number of electrons for an atom in an isolated state is equal to the number of protons because an atom is electrically neutral, the number of positive charges is equal to a number of negative charges. However, for ions, the number of electrons may be different.
Number of Neutrons
Neutrons have no charge but mass nearly as equal to of proton i.e. 1.675*10^-24 grams. The number of neutrons in an atom is not fixed, same elements may have atoms with different number of neutrons. Number of neutrons in an atom is obtained by subtracting atomic number from atomic mass (Z) i.e A – Z.
Hydrogen has one proton but can have 0 or 1 or 2 neutrons. But, almost 99.98% of the hydrogen atoms found in nature have zero neutrons. Similarly, there are variations in number of neutrons for each and every element resulting different isotopes. These isotopes are found in different proportion in nature according to their stability.