Ionic Bonds Chapter 8, Section 1

Vocabulary Anion Cation Chemical bon Formula unit Ionic bond Lattice energy Monatomic ion Oxidation number Polyatomic ion Alloy Delocalized electrons Electrolyte Electron sea model Metallic bond Oxyanion

Ionic Compounds What are Chemical Bonds Force that holds 2 atoms together Attraction between + nucleus and – electron Attraction between + ion and – ion Valence electrons make bonds

Ionic compounds What are chemical bonds? (cont) Elements react to form a stable octet (noble gas configuration). The + and – charges act like opposite poles of a magnet. Opposites attract strongly Likes repel strongly Strength diminishes with distance

Ionic Compounds How are positive ions formed? Atom loses one or more VALENCE electrons Called a CATION Ion becomes more stable by losing electrons (octet rule) Not a change in atom, Just an ion Loses all electrons in outer shell Reactivity depends on ease of losing electrons Transition metals usually form 2+ or 3+ ions shown with a (II) or (III)

Ionic Compounds How are positive ions formed? Group 1A loses 1 valence electron Group 2A loses 2 valence electrons Group 3A (13) loses 3 valence electrons Group 4A (14) does not generally make ionic compounds

Ionic Bonds How are positive ions formed ? (Cont) Transition metals give up the 4s electrons to make pseudo- noble gasses

Ionic Bonds How do negative ions form? Atoms gain negative electrons Nonmetals have a great attraction for electrons Adding electron fills up the shell = stable Called an ANION Naming: change name to end in –ide Gaining enough electrons to fill outer shell (octet rule) 7A gains 1 6A gains 2 5A gains 3

Ionic Compounds Ionic compounds are Metal+ and Nonmetal- Metals make Cations Groups 1A (1) – 3A (13) and all Group D elements Form + ions Nonmetals make Anions Group 5A (15) - 7A (17) Nobel Gasses (Group 8A/18) do not form compounds. Why?