The universe and things around us are made up of atoms, yes, even humans are made up of atoms.
And atoms are made up of sub-atomic particles; protons, neutrons, and electrons.
General Features of Sub-Atomic Particles
- Mass
Mass of proton is 1
Mass of neutron is 1
Mass of electron is 0
- Unit of Mass of Atoms:
Here, the unit of mass is expressed in amu (atomic mass unit). But usually, it is not mentioned.
- The Mass of Electron is Negligible:
Although electron has mass, it is negligible.
To understand, let us consider the following analogy of measuring the mass of a man and an ant.
Although ant has mass in comparison with human, it is negligible. So, it is also similar with the mass of an electron being negligible in comparison with the mass of proton.
2. Charge:
a. Nuclear Charge:
We know, that protons and neutrons are located in the nucleus of the atom and neutron doesn’t have any charge. Hence, the nucleus carries only positive charge from protons.
b. Counting Charges:
i. From the Number of Protons
1 Number of Proton = 1 Positive Charge
2 Number of Protons = 2 Positive Charges
ii. From the Number of Electrons
1 Number of Electron = 1 Negative Charge
2 Number of Electrons = 2 Negative Charges