Larger Molecular Shapes

[Josephine_Tang_1N]

If a molecule has enough atoms to have different structures depending on which you count as the central atom, how would you describe the molecular shape? For example, (CH3)2Be is a linear structure when considering Be as the central atom, but the carbon would be considered tetrahedral on its own?

[Chem_Mod]

Your thinking is correct. In such cases, we specify the shape around an arbitrary central atom. So for your example, if our central atom is Be, then the molecule is linear and Be is sp hybridized. However, if we make one of the C atoms the central atom, then the shape is tetrahedral and the hybridization on C is sp³.