How can I tell whether or not a molecule is planar? Otherwise, its structure allows it to be planar Even though the molecule will have a structure that allows for it to exist in a planar conformation, there may be some many that do not persist in a planar conformation due to steric effects, or complex three dimensional geometries
Why is [PdCl4]2- square planar whereas [NiCl4]2- is tetrahedral? The molecule $\ce { [PdCl4]^2-}$ is diamagnetic, which indicates a square planar geometry as all eight d electrons are paired in the lower-energy orbitals However, $\ce { [NiCl4]^2-}$ is also $\mathrm {d^8}$ but has two unpaired electrons, indicating a tetrahedral geometry
Why is the crystal field splitting energy larger for square planar than . . . 1 It is because of the fact that square planar complexes are formed by much strong ligands with d8-metal cation of 3d- series transition metals cation and 4d or 5d-series transition metal cation with either weak or strong ligands The very strong ligands and 4d or 5d-series transition metal cations are responsible for higher crystal field
Why is tetraamminecopper (II) a square planar and not a tetrahedral . . . It is not square planar but a Jahn-Teller distorted octahedron You can check out its structure in the image below You can fill electrons into the energy diagram in a standard fashion You will arrive at the $\mathrm {d}_ {x^2-y^2}$ orbital for the unpaired electron — the one pointing towards the four ammine ligands