electron configuration11.pdf

Elements in the periodic table objectives Explain the significance of quantum numbers Write the electron configuration of elements Explainthe basis of the arrangement of elements in the periodic table Draw the Lewis dot symbol of elements The Quantum-Mechanical Model of an Atom Und...

Elements in the periodic table objectives Explain the significance of quantum numbers Write the electron configuration of elements Explainthe basis of the arrangement of elements in the periodic table Draw the Lewis dot symbol of elements The Quantum-Mechanical Model of an Atom Understanding Quantum Theory of Electrons in Atoms The goal of this section is to understand the electron orbitals (location of electrons in atoms), their different energies, and other properties. The use of quantum theory provides the best understanding to these topics. This knowledge is a precursor to chemical bonding. Principal quantum number (n) Indicates the size of the orbital. The bigger the n is, the greater is the average distance of an electron in the orbital from the nucleus  Azimuthal quantum number The azimuthal (or orbital angular momentum) quantum number describes the shape of a given orbital. It is denoted by the symbol ‘l’ and its value is equal to the total number of angular nodes in the orbital. A value of the azimuthal quantum number can indicate either an s, p, d, or f subshell which vary in shape. Magnetic Quantum Number The total number of orbitals in a subshell and the orientation of these orbitals are determined by the magnetic quantum number. It is denoted by the symbol ‘ml’. This number yields the projection of the angular momentum corresponding to the orbital along a given axis. Magnetic Quantum Number Spin Quantum Number The electron spin quantum number is independent of the values of n, l, and ml. The value of this number gives insight into the direction in which the electron is spinning, and is denoted by the symbol ms.  It is important to note that it is impossible for two electrons of the same atom to have exactly the same quantum state or exactly the same values of the set of quantum numbers, as per Hund’s rules.  Electron distribution Electron Is important in understanding chemical reactions. distribution  The basic electron distribution is made when an atom is in its ground state. “Ground state” means that the atom’s electron occupy the lowest possible energy levels. 3 general rules in electron Aufbau principle distribution Pauli Principle Hund’s rule Aufbau principle Statesthat the electrons should occupy first the orbitals with the lower energy before those with higher energy. Pauli Principle States that no two electron in the same set of quantum numbers. Hund’s rule Hund’s rule of maximum multiplicity suggests that the most stable arrangement of electrons in subshells is the one with the greatest number of parallel spins.