Chapter 7 Outline

1. The Pauli Exclusion Principle. The basic idea of the Pauli Exclusion principle is that two electron's can't be in the same place with the same spin. Each orbital can hold two electrons, one with the spin up and the other with the spin down. This fits in with the quantum numbers n, l and m_l in the previous chapter. The quantum number m_s is for the electron spin. m_s can have a value of +1/2 (up) or -1/2 (down).
2. Atomic Subsheel Energies and Electron Assignments. The electron configuration for atoms are grouped into shells, you can think of these like layers of an onion. The shells are related to the principal quantum number (n). The l quantum number is related to the types of orbitals within each shell. These shells are ordered in increasing energy. Electrons fill the shells from the lowest energy up. This chapter will show you how to determine the electronic structure of an atom. This structure is based upon the energy of the orbitals and the order in which they are filled. Understanding the electronic structure of an atom will provide many clues about how it will behave. If you understand the electronic structure, you can figure out the chemistry that will happen. This is an extremely powerful tool for understanding chemistry. This insight will allow you to figure out chemical reactions instead of trying to memorize all of them. Since there are billions of possible chemical reactions, the effort that you put into this chapter will pay off (unless you think you can memorize about 1000 reactions for this class, and several thousand more if you take organic).
3. Atomic Electron Configurations of Atoms. This section discusses how to determine the elecron configuration for an atom. You should be able to fill in an energy level diagram, write the orbiatl box notation, write the spectocopic notation, and write the sets of quantum numbers for any element. Careful examination of Table 8.2 shows that there are a number of exceptions to the general trends for electron configuration. YOU ARE NOT RESPONSIBLE FOR KNOWING ALL THE EXCEPTIONS. You do need to know that there are exceptions.
4. Electron Configurations of Ions. This section discusses how to determine the electron configuration for an ion.
5. Atomic Properties and Periodic Trends. This section connects the electronic configuration of atoms to the periodic table developed by Meldeleev 28 years before J.J. Tomson discovered the electron. You should be able to predict trends in atomic size, ionization energy, electron affinity, and ion size.
6. Periodic Trends and Chemical Properties. The electronic configuration of atoms also gives rise to the periodic trends in chemical properties of elements.

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