Question

Further, the d-orbitals of the transition element project to the periphery of the atom more than the s and p-orbitals. Hence the d-electrons effect the properties of the elements to a great extent.

Answer 1

d-$e^{-}s$ are present at the periphery means boundary of an atom than s and p-$e^{-}$. The $e^{-}s$ in sound p-orbitals are embedded inside the atom, rather closer to the nucleus and d-$e^{-}$ are at the boundary hence effect the surrounding environment. Hence the outermost d-$e^{-}$ effect the properties of the elements to a larger extent.