Beryllium chloride (BeCl2) is a linear molecule despite forming covalent bonds due to its unique electronic configuration and molecular geometry.
In BeCl2, beryllium (Be) has two valence electrons, while each chlorine atom (Cl) has seven valence electrons. To achieve a stable electron configuration, beryllium can undergo a process known as electron pair sharing or covalent bonding with the chlorine atoms. Each chlorine atom can contribute one electron to form a covalent bond, resulting in two shared electron pairs between beryllium and each chlorine atom.
The bonding in BeCl2 can be represented as Be:Cl-Cl, indicating that beryllium shares its two electrons with the two chlorine atoms. This sharing of electrons leads to the formation of two single covalent bonds.
Now, let's consider the molecular geometry of BeCl2. The electron pair geometry around beryllium is linear. This occurs because there are only two regions of electron density, which are the two shared electron pairs. According to VSEPR (Valence Shell Electron Pair Repulsion) theory, electron pairs repel each other and try to maximize their separation to minimize repulsion. As a result, the shared electron pairs arrange themselves in a linear configuration to achieve the maximum separation.
Therefore, despite being a covalent compound, BeCl2 adopts a linear molecular geometry due to the arrangement of its bonding electron pairs, resulting in a linear molecule.