Ionic Compounds Chapter 8

Forming Chemical Bonds Chemical Bond: The force that holds two atoms together. Valence Electrons Opposite forces attract Octet Rule

Positive Ions Lose e- becomes cation. Atoms can lose electrons to become more stable. Na+1 is more stable than Na.

Negative Ions Gain e- to become anions Gain electrons to gain more stable e- config Cl-1 is more stable than Cl

Formation of Ionic Bond Ionic Bond: electrostatic force that holds oppositely charged particles together in an ionic compound. Occurs between metals and nonmetals. Called ionic compounds.

Formation of Ionic Bond NaCl, 1 to 1 ratio of Na and Cl Na+1 and Cl-1 combine Oxidation numbers = 0 MgCl? CaO

Properties of Ionic Compounds + and – ions in regular pattern Forms crystals EX: salt Crystal lattice forms Strong bonds between them Have ↑ melting point and boiling point If aqueous solution can conduct electricity electrolyte.

Properties of Ionic Compounds Formation of ionic compounds is almost always exothermic. Lattice energy: amount of energy required to separate ions of an ionic compound. Smaller ions have more negative lattice energy. EX: LiCl more negative NaCl Larger charges have larger lattice energy. EX: MgO more negative MgCl

Formulas for Ionic Compounds Formula Unit: Simples ratio of ions in ionic compound Know your oxidation states for monatomic metals and nonmetals Also know your oxidation states for polyatomic metals and nonmetals Group Oxidation number 1 1+ 2 2+ 15 3- 16 2- 17

Oxidation Numbers Transition metals have multiple oxidation numbers. Oxidation number: # of e- transferred from an element to form an ion.

Naming Ionic Compounds Cation always named first. Cation name does not change. (Na1+, sodium) Ex: NaCl = sodium chloride Anion named by taking root and adding –ide. (O2-, oxide) Ex: CaO = Calcium Oxide

Naming Ionic Compounds Transition Metals with multiple oxidations must include their oxidation state in the name of the compound. [Fe2+, Iron (II)] EX: FeO = Iron (II) oxide EX: Fe2O3 = Iron (III) oxide If an atom contains a polyatomic ion simply name that ion. Know oxidation states of polyatomic ions. EX: NaOH = Sodium Hydroxide EX: AgNO3 = Silver Nitrite

Naming Ionic Compounds Older method of naming transition metals Root word followed by –ous, for lower oxidation, or –ic, higher oxidation EX: Cuprous ion = Copper (I) EX: Cupric ion = Copper (II) EX: Ferrous ion = Iron (II) EX: Ferric ion = Iron (III)

Naming Ionic Compounds Yes No

Metallic Bonds and Properties of Metals Metals do not bond ironically Form electron sea Electrons are not held by 1 atom Delocalized e-, free to move Metallic bond: attraction of metallic cation for delocalized e-.

Metallic Properties Very different melting points. Hg -38 C, W 3422 C. Ductile and malleable. Delocalized e- cause metals to be good conductors. Mobile e- interact with light releasing photons causing luster.

Metal Alloys Alloy: mixture of elements that have metallic properties. EX: steel, Brass Substantial Alloy: atoms of original metallic solid replaced by other metal atoms of similar size Interstitial Alloy: small holes in a metallic crystal are filled with smaller atoms