what is the electron-pair geometry for Be in BeF2? There are no lone pairs around the central atom, so the geometry of BeF2 is linear. B: What is the electron-pair geometry for Be in BeBr2? There are no lone pairs around the central atom, so the geometry of BeBr2 is linear.
The Correct Answer and Explanation is:
Correct Answer:
The electron-pair geometry for Be in BeF₂ is linear.
The electron-pair geometry for Be in BeBr₂ is also linear.
Explanation:
Beryllium (Be) is the central atom in both BeF₂ and BeBr₂. In each of these molecules, Be forms two single bonds with two halogen atoms (either fluorine or bromine). To determine the electron-pair geometry, we consider the regions of electron density around the central atom.
Beryllium has an atomic number of 4, so its electron configuration is 1s² 2s². In compounds like BeF₂ or BeBr₂, it uses the 2s orbital and promotes one electron to form two bonding orbitals, allowing it to bond with two halogen atoms. Although beryllium does not follow the octet rule strictly (since it is stable with just four electrons in many of its compounds), it does form two bonds.
Since there are only two regions of electron density (each bond counts as one), and no lone pairs on the Be atom, the electron-pair geometry is determined solely by these two bonding regions. To minimize repulsion between them, the two bonded atoms arrange themselves as far apart as possible, resulting in a linear geometry with a bond angle of approximately 180 degrees.
This applies to both BeF₂ and BeBr₂. The type of halogen (whether it is fluorine or bromine) does not change the number of bonding regions around the central atom. Both molecules contain only two electron domains around beryllium, with no lone pairs. Therefore, the molecular geometry and the electron-pair geometry are both linear for these compounds.
This conclusion is supported by VSEPR theory (Valence Shell Electron Pair Repulsion), which predicts the spatial arrangement of electron domains to minimize repulsions.
