Requirements management - Overview. 1  The purpose of requirements management is to ensure that an organization documents, verifies, and meets the needs and expectations of its customers and internal or external stakeholders. Requirements management begins with the analysis and elicitation of the objectives and constraints of the organization.
The highest occupied electron shell is called the valence shell, and the electrons occupying this shell are called valence electrons. The chemical properties of the elements reflect their electron configurations. For example, helium, neon and argon are exceptionally stable and unreactive monoatomic gases.
The valence electrons of an atom are those electrons that are in its outer energy shell or that are available for bonding. The American chemist Gilbert Newton Lewis (1875-1946) introduced a useful way to represent electrons in the valence shell of an atom. For elements in Groups IIIA through VIIIA the outermost s and p electrons in the highest energy shell are valence electrons. 2  For transition elements the valence electrons are those in the outermost s sub-shell and in the d sub-shell of the next to outermost energy shell.