these are some review questions for an exam: 1.why are s-orbital spherically symmetric? 2.What is the probability of finding an electron at or very near to the nucleus? (1s, 2s, 2p... 3.Why does the curve for 1s go to zero for r-> 0? (the curve of the probability density associated with the radial parts of the hydrogen atomic wave functions) 4.Why do we denote p-orbitals by px, py, and pz? 5.How many nodal planes do 1s,2s,3s.. orbitals have? What about 2p,3p... orbitals? And finally, 3d...orbitals?