2. The emission spectrum of an unknown element contains two lines-one in the visible portion of spectrum and the other, ultraviolet. Based on Figure 1.1 and on what you have learned about Niels Bohr’s model of atom, account for the difference in energy between these lines. (3 marks)
Answer: The line which is on the visible portion of spectrum is produced when electron is jumping from higher to lower energy level orbit thus releasing energy and electromagnetic waves featuring longer wavelengths, which mean that these lines are lower in energy compared to line which is emitting on ultraviolet portion of spectrum. The line which is on ultraviolet region of spectrum indicates that electron is jumping from highest (higher than previous one) energy level orbit to lowest energy level orbit thus releasing more energy and waves of shorter wavelengths.
a. Draw the energy-level diagram and write the electronic configuration for zirconium (element 40). (3 marks)
Energy-level diagram for zirconium is drawn below:
Electronic configuration for zirconium is given below:
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d2
b. Use the diagram to explain why the Zr4+ ion exists. (2 marks)
When the outer orbitals are filled with applicable number of electrons the element tends to becomes chemically stable under normal conditions.
Zirconium atomic structure contains 40 electrons. The nearest noble gas element to zirconium is Krypton, which contains 36 electrons.