Figure 2 shows the boundary surface of 2p orbitals of a hydrogenic atom hree dimensions. (i) What are the number 2 and the letter p in the name '2p orbital stand for? (v) Describe how the px, py and pz orbitals are differentiated and named as such. (vi) Some people say that the non-spherical shapes of the orbitals in Figure 2 can only be obtained by using quantum mechanics. Do you agree? Elaborate. 2.

(a) The position of an electron is known to within 14.4 Å (1.44×10- m). What is the minimum uncertainty in its velocity? m s- 1 S (b) Repeat the calculation of part (a) for a carbon atom. ms-1 S

5)

Calculate the de Broglie wavelength for: (a) an electron with a kinetic energy of 100 eV. (b) a proton with a kinetic energy of 100 eV. (c) an electron in the rst Bohr orbit of a hydrogen atom.

The lowest five energy states in the Helijum atom (Z=2) have the following energy levels (assuming at least one electron is in the ground state.) Зр; -1,4eV _3s; -1.7eV _2p; -3.4eV _2s; -4.0eV _1s; -24.5eV A) Find one wavelength of light that you could shine on a collection of helium atoms to make a laser. Consider selection rules for all transitions. Explain your reasoning!! B) What wavelength(s) would the output laser beam have? C) Calculate the quantum efficiency of the laser.