Ch. 7 Chemical Bonding

7-1: Ionic Bonding Ionic bond: occurs when a positively charged ion is attracted to a negatively charged ion. In general, one atom takes electrons from another. Ionic compound: composed entirely of ions Cation: positively charged ion Anion: negatively charged ion

Properties of Ionic Compounds tend to dissolve in water have high melting points due to strong bonds are brittle when molten (liquid), are good conductors

Octet Rule: atoms tend to gain, lose or share electrons in order to acquire a full set of valence electrons Lewis Dot Diagrams Examples

Types of Ions Monatomic: have only one atom If it is a cation, the name of the ion is the name of the atom. Ex: Ca+2 = calcium ion Transition metals can have more than one charge. If the cation is a transition metal, it will have a number to distinguish charge. Ex: Fe can have a +2 or +3 charge, so ion names are iron (II) and iron (III) If it is an anion it will end in –ide. Ex: F-1 = fluoride (nor fluorine!)

Cations (fill in the missing info) Atom Ion Name Ion Rule # Calcium Ca+2 1 Lithium Copper Copper (I) 2 Cu+2 Iron Iron (III) Fe+3

Anions (fill in the missing info) Atom Ion Name Ion Rule Oxygen Oxide 3 Fluorine F- S-2

Binary Ionic Compounds: Form from the ions of only two elements. To name them, just put the name of the cation and anion together. Ex: BaCl2 = ions are barium and chloride, so the name is barium chloride Ex: MnF2 = ions are manganese (II) and fluoride, so manganese (II) fluoride

Polyatomic Ions: Ions that contain more than one atom

Polyatomic Ion Name Ion symbol and charge Ammonium NH4+ Hydroxide OH- Acetate C2H3O2- Nitrate NO3- Carbonate CO3-2 Sulfate SO4-2 Phosphate PO4-3 Hypochlorite ClO-1 Bicarbonate HCO3-

Naming using polyatomics Again, just give the names of the ions Ex: NH4Cl = ammonium and chloride, so ammonium chloride Ex: MgSO4 = magnesium and sulfate, so magnesium sulfate Ex: CuNO3 = copper (I) and nitrate, so copper (I) nitrate