That was I thought but I wasn't sure, thanks by the waymfb said:
The reason 5 Si atoms do not bind with added Phosphorus is due to the difference in their electronic configurations. Si atoms have 4 valence electrons, while Phosphorus atoms have 5 valence electrons. This difference in electron count makes it difficult for them to form stable bonds.
Yes, it is possible for 5 Si atoms to bind with added Phosphorus, but it requires the presence of a strong reducing agent or high energy conditions. Under normal circumstances, the electronic configurations of these atoms prevent them from forming stable bonds.
The size of the atoms does play a role in their ability to bind. Si and P atoms are relatively similar in size, but the addition of an extra electron in Phosphorus makes the atom larger. This difference in size makes it challenging for them to form strong bonds with each other.
Yes, there are some exceptions to this rule. For example, in the crystal structure of Silicon Phosphide (SiP), 5 Si atoms are able to bind with added Phosphorus due to the specific arrangement of atoms in the crystal lattice. However, this is a rare occurrence and not the norm.
The difference in electronegativity between Si and P also contributes to their difficulty in bonding. Si has a lower electronegativity than P, meaning it is less likely to attract and share electrons. This makes it challenging for them to form stable bonds, as they are not able to share electrons equally.