CHEM 1111 Chapter 4: Chapter 4 - Periodic Trends of the Elements
Document Summary
Periodicity: phenomenon of the regular, periodic occurrence of properties (mendeleev) Made possible to predict the properties of elements that had not yet been discovered. Exception: argon"s atomic mass > potassium"s atomic mass, but it"s listed first. Periods share same value of n in the first column (new line, new n) 3p5, 2p5. Main group elements: (aka representative elements) groups 1a through 7a. Transition metals: have incompletely filled d subshells or readily lose electrons to achieve incompletely filled d subshells. Exception: group 2b are technically not transition metals b/c they have completed d subshells. Lanthanides and actinides: incompletely filled f orbitals. Valence electrons: outermost electrons that determine how atoms interact with one another. Nuclear charge (z): simply the number of protons in nucleus of an atom. Effective nuclear charge (zeff): magnitude of positive charge that is experienced by an electron in the same atom. Only atom in which z=zeff is hydrogen.
