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Unformatted text preview: 1 1 Lecture 9 square4 Ionic vs Molecular compounds ( select information from Chapter 7) square4 Introduction to Nomenclature (Chapter 8) square4 Naming ionic compounds 1 Points to note: square4 valence electrons are in the outer most regions of the atom square4 ions form by losing or gaining electrons square4 When an electron is lost it is one of the valence electrons that is lost square4 special stability is associated with a filled shell electron configuration (noble gas electron configuration) square4 some extra stability with a half filled shell 2 The Octet Rule see Chapter 7.3 square4 In forming compounds, atoms of elements lose, gain, or share electrons in such a way as to produce a noble gas electron configuration for each of the atoms involved. square4 Octet: a noble gas electron configuration has 8 valence electrons (except for He) Ne: 1s 2 2s 2 2p 6 3 Types of Compounds Ionic Compounds Molecular Compounds From the combination of anions and cations NaCl MgBr 2 From the combination of neutral atoms H 2 O CCl 4 Dissolved in water, ions dissociate and move freely in solution Solutions of ionic compounds tend to conduct electricity When dissolved in water the molecules remain in their units Solutions of molecular compounds tend not to conduct electricity 4 2 2 Ionic Compounds square4 Ionic compounds are made up of cations and anions , in such a way that the charge balances to give a neutral compound square4 Formation of Ions in relation to position in the periodic table: general observation: metals tend to form cations non metals tend to form anions Why? 5 Ion Formation and the Periodic Table square4 Group IA, the Alkali Metals Na → Na + + e- 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 All the Alkali Metal elements will tend to lose 1 electron to form a +1 cation that has the same electron configuration as the preceding Noble gas element 6 square4 Group IIA, the Alkaline Earth Metals Ca...
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