Answer:
Explanation:
EDDs stands for electron distribution diagrams
Electrons are located in the atoms in regions named orbitals, instead of they being circulating in orbits. Each orbital can accept a maximum of two electrons, which is a consequence of the fact that two electrons in an atoms cannot have the same set of four quantum numbers, and is expressed by Pauli's exclusion principle.
Thus, if an orbital has two electrons, they will have identical principal quantum number, azimuthal quantum number, and magnetic quantum number, but they will have opposite spin number. Since, there are only two spin numbers (+1/2 and -1/2), a maximum of two electrons can occupy each orbital.
The other importand principle, is the named Hund's rule. This rule states that: before an orbital is occupied by two electrons (with opposite spins), all the orbitals of the same sublevel of energy (equal value of the other three quantum numbers) must be occupied.
The reason of this, is that the electrons will disperse as much as possible, in the different orbitals, which have the same set of three quantum numbers, to avoid the electrostatic repulsion from occupying the same orbital.
Thus, the electrons will be unpaired, this is located in different orbitals with equal spin numbers, until all the orbitals are occupied, and only then new electrons will be added one by one, pairing them with the electrons that were first added, by showing opposite spins.
