Protons- These are positively-charged particles present in the nucleus.
Neutrons- These are neutral particles present in the nucleus.
Electrons- These are negatively-charged particles which revolve around the nucleus.
Atomic number - The atomic number of an element is the number of protons present in one atom of the element, which is represented by the letter Z.
Mass number - The total number of protons and neutrons present in one atom of an element It is represented by the letter ‘A’.
Rules for Electronic Arrangement- The maximum number of electrons which can be accommodated in any energy level of an atom is given by 2n2, where n is the orbit number or energy level index 1, 2, 3,4 . . . The outermost shell of an atom cannot accommodate more than eight electrons, even if it has the capacity to accommodate more.