Atomic Structure - Employee Web Site：原子结构-员工网站.pptVIP

Atomic Structure The theories of atomic and molecular structure depend on quantum mechanics to describe atoms and molecules in mathematical terms. Quantum Mechanics The Bohr Atom (quantization of energy levels) The equation only works well for hydrogen-like atoms. Wave nature of the electron E = h? = hc/?, ?=h/mv (de Broglie wavelength) Not possible to describe the motion of an electron precisely. Heisenberg’s Uncertainty Principle ?x?px ? h/4? Electrons in an atom have to be described in regions of space with certain probabilities. The Schr?ndinger Equation Describes the wave properties of an electron in terms of its position, mass, total energy, and potential energy. Based on the wavefunction, ?, which describes an electron wave in space (i.e. orbital). The equation used for finding the wavefunction of a particle. Used to find the wavefunctions representing the hydrogenic atomic orbitals. The Schr?ndinger Equation (SE) H? = E? H is the Hamiltonian ‘operator’ which when operating on a wavefunction returns the original wavefunction multiplied by a constant, E. Carried out on a wavefunction describing an atomic orbital would return the energy of that orbital. There are infinite solutions to the SE; each solution matching an atomic orbital. Each solution (or ?) is represented with a set of unique quantum numbers. Different orbitals have different ? and, therefore, different energies. The Schr?ndinger Equation (SE) Properties of the wavefunction, ?. Probability of finding an electron at a given point in space is proportional to ?2. The ? must be single-valued. The ? and its 1st derivative must be continuous. The ? must approach zero as r approaches infinity. The probability of finding the electron somewhere in space must equal 1. All orbitals must be orthogonal. Quantum Numbers and Atomic Wavefunctions Implicit in the solutions for the resulting orbital equations (wavefunctions) are three quantum numbers (n, l, and ml). A fourth quantum number, ms accounts for the