Be can show coordination number four while other members show a value ...
Coordination number of Be
The coordination number refers to the number of atoms, ions, or molecules that surround an atom or ion in a crystal lattice. It indicates the number of nearest neighbors that a particular atom has in a solid. In the case of beryllium (Be), it is known to exhibit a coordination number of four, while other members of its group in the periodic table show a coordination number of six.
Reasons for coordination number difference
There are several reasons why beryllium has a coordination number of four while other members exhibit a coordination number of six:
1. Small size of Be:Beryllium has a smaller atomic radius compared to other elements in its group. The smaller size of Be atoms makes it energetically unfavorable for six atoms to be in close proximity to it. Due to the smaller atomic size, Be can accommodate only four neighboring atoms comfortably.
2. Non-availability of d orbitals in Be:Beryllium belongs to the s-block elements, and its electronic configuration is 1s²2s². It does not have any d orbitals in its valence shell. The coordination number is often influenced by the availability of d orbitals for bonding. Since Be does not possess any d orbitals, it cannot participate in coordination with more than four atoms.
3. High ionization enthalpy of Be:Beryllium has a relatively high ionization enthalpy, meaning it requires a significant amount of energy to remove an electron from a Be atom. This high ionization enthalpy makes it less likely for beryllium to form additional bonds and increase its coordination number beyond four.
Conclusion
In conclusion, beryllium exhibits a coordination number of four due to its small size, non-availability of d orbitals, and high ionization enthalpy. These factors make it energetically unfavorable for Be to have a coordination number of six like other members of its group.