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Electron configurations. Heisenberg’s Uncertainty Principle.
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Heisenberg’s Uncertainty Principle In 1927, Werner Heisenberg proposed his uncertainty principle which states that the position and the momentum of a moving object cannot simultaneously be measured and known exactly. This concept becomes critical in dealing with small particles like electrons.
The probability of finding an electron in various locations around the nucleus can be pictured in terms of a blurry cloud of negative charge. The cloud is most dense where the probability of finding the electron is highest. The cloud is least dense where the probability of finding the electron is lowest. The density of an electron cloud is referred to as electron density.
Orbitals and Energy • The probability of finding electrons in certain regions of an atom is described by orbitals. • An atomic orbital is a region around the nucleus of an atom where an electron with a given energy is likely to be found.
Orbitals have characteristics shapes, sizes, and energies. There are several different kinds of orbitals, each having different fundamental shapes. These different kinds of orbitals are designed by the letters s, p, d, and f. All sorbitals are spherical in shape, whereas, porbitals are dumbbell shaped. The shapes of d and forbitals are more complex.
The main or principal energy levels in an atom are designated by the quantum numbern. There are seven energy levels. Each principal energy level is divided into one or more sublevels (s, p, d, and f). Each sublevel is divided into orbitals.
Electron Configuration • Electron configurationis the distribution of electrons among the orbitals of an atom. Electron configurations of atoms are determined by distributing the atom’s electrons among levels, sublevels, and orbitals based on a set of stated principles.
Practice ProblemsWrite the electron configuration for thefollowing elements: (1) H -