CHEM101 Lecture Notes - Lecture 8: Valence Electron, Electron Affinity, Periodic Function

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CHEM101 Full Course Notes
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CHEM101 Full Course Notes
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Chem 101 - lecture 8 - trends of the periodic table. Note: read 8. 3 and skip electron affinity p. 343. Non - metals will gain electrons while metal elements will lose electrons to achieve noble gas configuration. In atoms: 4s is lower in energy than 3d. The same pattern holds for 5s vs. 4d. In ions: 3d has a much lower energy than 4s. Therefore, the first electron to be removed are 4s electron. Thus the pattern in ions vs. atoms is reversed. Fe - [ar] 4s2 3d6 is the ground state configuration for iron. Fe2+ - [ar] 3d6 (the 4s electrons are removed first) Chemical and physical properties are a periodic function of atomic number. Most periodic properties can be explained by core and valence electrons. Core electrons (inner electrons) do not participate in bonding. Valence electrons (outer electrons) take part in bonding. This means that electrons are arranged in shells.