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Chapter 5. The Periodic Law. Periodic Law. Mendeleev set up the periodic table, and IUPAC continues to do so, by grouping properties together (families are alike) In 1860, over 60 elements were discovered Mendeleev was able to correctly predict properties of unknown elements
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Chapter 5 The Periodic Law
Periodic Law • Mendeleev set up the periodic table, and IUPAC continues to do so, by grouping properties together (families are alike) • In 1860, over 60 elements were discovered • Mendeleev was able to correctly predict properties of unknown elements • See board for drawing of regions of periodic table and group names
Valence electrons • Valence- outermost shell • How to calculate maximum possible electrons in shell
Octet rule • Octet rule- except for the 1st shell (2 electrons), all shells need 8 electrons to be completely filled (“happy”) • See electron configuration for noble gases • See board for charges and electron configurations
Groups: Alkali Metals • H is not one, “social butterfly” that can be group 1 or 7 (halogen) • Silvery, soft, quick to bond, forms hydrogen gas (flammable) in water, most reactive metals, form strong bases • Ex. of base = Drano (sodium hydroxide)
Alkaline Earth Metals • Harder, denser, stronger than alkali, higher melting point, harder to bond, very reactive, also forms hydrogen gas in water, can form strong base • Example of base= milk of magnesia
Transition Metals • Good conductors, high luster (shine) • +1, +2, +3 charge • Aqua regia – “royal liquid” that dissolves even gold • Electron configuration of Fe (what is the outer shell?) • Cu and Cr electron configuration exceptions
Halogens, Lanthanides, Actinides • Halogens- most reactive nonmetals • Lanthanides- most manmade, shiny, like group 2 • Actinides- most manmade • Th-Np can be found naturally
Trends- Atomic radius • Radius- ½ distance between 2 identical atoms bonded together • See trend on board and problems
Ionization Energy • Ionization energy- energy needed to separate 1 electron from outermost shell • Ion can be + or – charged atom or group of bonded atoms • 1st ionization energy<2nd<3rd • See board for trend, problems
Electron Affinity • Electron affinity- how easy to gain electrons • See board for trend, problems
Electronegativity • Electronegativity- ability to attract already bonded electrons (homewreaker) • See trend, problems on board
Ionic radius trend • Cation- +, smaller than original • Anion is -, larger than original • See board for trend, problems