1. The development of MRI imaging technology is one useful spinoff of basic research into structure of the atom. Research, however, is expensive. Many people argue that high cost of research outweighs its potential benefits. Provide one argument for and one argument against increasing current funding for atomic-structure research. Use specific examples from this lesson in your answer to support each position. (6 marks) Answer: 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.
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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. 3. 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: 4d 5s 4p 3d 4s 3p 3s 2p 2s 1s Electronic configuration for zirconium is given below: s2 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. Therefore, Zirconium will lose 4 electrons, 2 electrons from 5s orbital and 2 electrons from 4d orbital.
The energy-level diagram for Zr4+ will look like following: 4p 3d 4s 3p 3s 2p 2s 1s This energy-level diagram is also similar to Krypton energy-level diagram. c. Compare the stability of the Zr atom and the Zr ion. Account for any difference in their stability. (2 marks) Zr atom is neutral i. e. , have 40 electrons and 40 protons. However Zr 4+ ion is charged ion and chemically stable. The outer sub-levels is filled with applicable number of electrons making it difficult to react