BINARY IONIC COMPOUNDS Naming and Writing formulas Ionic

BINARY IONIC COMPOUNDS Naming and Writing formulas

Ionic Compounds: • Formed by combining a cation with an anion. • Held together by an ionic bond • The attractive force between ions of opposite charge. • Crystal lattice structure: • Repeating ordered pattern of positive and negative ions • Represented by a formula unit • Displays the lowest ratio of ions in the crystal • Example: Ca. Cl 2 •

Examples of crystal structures

Naming Binary ionic compounds • Binary = 2 elements (metal w/ one nonmetal) • Step #1: • Name the cation first. • Step #2: • Name the anion using the –ide ending. • Example: • 1) Ba. F 2 • Barium fluoride • *subscript does not effect the naming

Learning Check 1. Name the following ionic compounds: • Answers: a. Na. O a. Sodium oxide b. Mg. I 2 b. Magnesium iodide c. Ca. Br 2 c. Calcium bromide d. Li 2 S d. Lithium sulfide

WRITING FORMULAS Binary Ionic Formulas

How do we know the Ion’s Charge? • Group 1 = +1 • Group 2 = +2 • Group 13 metals = +3 (Al, Ga and In) • Group 15 Nonmetals = -3 (N & P) • Group 16 Nonmetals = -2 • Group 17 = -1 • For Groups 3 -12 and Sn & Pb: • • • Roman Numerals equal positive charge* Example: Iron (III) = Fe+3 Copper (II) = Cu +2

Goal = Balance charges • The sum of the positive charges must equal the sum of the negative charges. • Overall charge equals zero! zero • Example: • Why is calcium chloride’s formula Ca. Cl 2 not just Ca. Cl? • Ca+2 • Cl-1 • You need 2(-1) chloride ions to balance the 1(+2) calcium ion.

Writing formulas: Criss-cross Method Write formulas for ions with charges. • Cation first, anion second. • Criss-Cross charges making them subscripts • Reduce if necessary. Always need lowest ratio of ions • • Example: • Magnesium fluoride

More examples • Lithium oxide • Aluminum selenide • Calcium sulfide • Iron (III) bromide

Review - Learning Check • Write the formulas for the following binary ionic compounds: 1. Manganese (III) oxide 2. Strontium sulfide 3. Calcium iodide 4. Chromium (VI) fluoride

Learning Check Answers 1. Manganese (III) oxide Mn 2 O 3 • 2. Strontium sulfide • Sr. S • 3. Calcium iodide • Ca. I 2 • 4. Chromium (VI) fluoride • Cr. F 6 •

NAMING IONIC COMPOUNDS WITH TRANSITION METALS Groups 3 -12 and Sn & Pb

Naming Compounds with Transition Metals • A roman numeral must appear in name when dealing with transition metals and Sn & Pb. • Work backwards from formula to determine charge on cation. ØExceptions: Zn+2, Ag+, Cd+2 • Example: Ni. Cl 2

Practice Problems: Name the following compounds 1. Cr 2 O 3 1. Chromium (III) oxide 2. Mn. S 2. Manganese (II) sulfide 3. Zn. Cl 2 4. Fe. I 3 3. Zinc chloride 4. Iron (III) iodide