aka The Wave Mechanical Model Video p.com/science/matt erandchemistry/ato micmodel/p.com/science/matt erandchemistry/ato micmodel/p.com/science/matt erandchemistry/ato micmodel/ The energy level of an electron is the region around the nucleus where it is likely to be moving. The electrons in an atom cannot stop between energy levels. To move from one energy level to another, an electron must gain or lose just the right amount of energy; the amount of energy gained or lost is not always the same The energy levels in an atom are not equally spaced. A quantum of energy is the amount of energy required to moved an electron from its present energy level to the next higher one. The higher an electron is placed on the energy ladder, the larger the diameter of the circular path or orbit of that electron. Energy Levels Electrons are found in principal energy levels, designated by the principal quantum number (n). (Bohr) n = 1, 2, 3, 4, 5... etc. Every principal energy level is divided into sublevels. (Schrdinger) Electrons are found in these sublevels in cloud-like regions called orbitals. There are 4 kinds of orbitals (s, p, d and f), each with a different shape. An orbital is not the path of an electron, merely the location we will most like find it. We identify the orbital of an electron using the Time-Dependant Schrdinger Equation. What the ?!?!?!? OK WAIT A MINUTE HOW DOES THAT TELL ME WHERE AN ELECTRON IS IN AN ATOM?!?!?!?!?!?!? Solving the Schrdinger Equation tells us where we are likely to find the electron. An orbital is NOT the path of an electron, only the region of space where we are most likely to find the electron. In order to solve the equation we need to use a special set of coordinates called quantum numbers. Consider, solve y = x 2 3x 5 You find these values. Regions of space where we are likely to find an electron in an atom. Any orbital can hold a MAXIMUM of 2 electrons. In each block of the periodic table we label the rows with number/letter combinations; the number written in the front is the principal quantum number, n. Max e - per n is 2n 2 s The s orbital Spherical in shape The lowest energy orbital for any given principal energy level (n) The p orbitals are dumbbell-shaped and there are 3 for any given principal energy level, n. There are 5 d orbitals at every principal energy level beginning at n = 3. There are 7 f orbitals beginning at n = 4. Electrons exist in orbitals. Each orbital can hold a maximum of 2 electrons. The ways in which electrons are arranged around the nuclei of atoms are called electron configurations. Three rules govern the filling of atomic orbitals by electrons, these rules are Aufbau principle, the Pauli exclusion principle and Hunds rule. Electron Configurations The first method of communicating the position of electrons is known as an energy level diagram. This method shows the energy levels along a vertical axis and then each orbital (and sub orbital) is represented by a dash with its type below it. To be proper, the vertical height of the dash represents the energy level and thus orbitals requiring a higher energy level should be higher. Electrons are represented by arrows (with only half a head). For now, you should now that when two electrons occupy an s orbital or a sub orbital they are said to have opposite spin. This will be explained later, but it is indicated by one arrow pointing up and the other pointing down on the dash. Draw out the orbital diagrams for the following elements; Hydrogen Helium Carbon Oxygen Xenon Cesium Quantum Numbers are used to solve the Schrdinger Equation and obtain atomic orbitals. Remember: electrons fill orbitals following the Aufbau Principle (diagram) We write e- configurations as follows: 1s 2 2s 2 2p 2 (for carbon) The first number indicates the principal quantum number, n The letter indicates the type of orbital (s, p, d, f) The superscript number indicates the number of electrons in that sub-level Write the electron configuration of S: 1s 2 2s 2 2p 6 3s 2 3p 4 Write the electron configuration of Fe: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 6 Write the electronic configurations for the following elements: Mn, P, He, Ar, Xe, Pt, K, Ti, Ga, B, W, U An abbreviated notation is used known as Noble Gas notation. Since all but the last few subshells are identical to those of one or another of the noble gases, we can make use of this. Phosphorus, for instance, differs from neon (1s 2 2s 2 2p 6 ) only by the presence of a third shell. Thus, the electron configuration of neon is pulled out, and phosphorus is written as follows: Phosphorus [Ne] 3s 2 3p 3 This convention is useful as it is the electrons in the outermost shell which most determine the chemistry of the element. Write out the Noble Gas notation for the following elements: Vanadium Aluminum carbon Oxygen Xenon Cesium Download Orbital Viewer here.here