Question

why do we only consider charge of electron and not of proton in quantization?​

Answer 1

Answer:

Proton—positive; electron—negative; neutron—no charge. The charge on the proton and electron are exactly the same size but opposite. The same number of protons and electrons exactly cancel one another in a neutral atom. ... It also shows that the number of electrons is the same as the number of protons.

Answer 2

Answer:

Because throughout the chapters, we actually deal about the behaviour of electrons. Protons are embedded in the nucleus and hence are immobile. You have to remember that by positive charge, one simply refers to the absence of certain number of electrons instead of excess of protons.