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.
Te has its valence electrons in the 5th shell and Se has its valence electrons in the 4th shell. Therefore, Te is bigger than O. Across the periodic table, the atomic radius decreases. The smallest atoms are found in the northeast (NW) or top-right corner of the periodic table. This trend follows Z(effective), which means that for elements in the same period, the valence electrons are all found in the same shell.