Lecture 69/12/05 Seminar today at 4 pm

Compounds & Molecules COMPOUNDS - combination of 2 or more elements in definite ratios Has unique characteristics from element H 2 O MOLECULES are the smallest unit of a compound that retains the characteristics of the compound. Ionic Compounds vs. Molecular Compounds

CATIONS – Positive ion Li → 1 e - + Li +

ANION – Negative ion F + 1 e - → F -

Predicting Charges on Monatomic Ions

Naming cations For metals:(name + ion) Al 3+ - Aluminum ion For metals with multiple possible charges: Use Roman numeral in parenthesis for charge -ous (lower charge) vs. –ic (higher charge) Copper (II) = cupric ion Copper (I) ion = cuprous ion NH 4 + is ammonium ion

Naming anions Monatomic ion: (-ide) Carbide (C 4- ) Nitride (N 3- ) Phosphide (P 3- ) Oxide (O 2- ) Fluoride (F - ) Halides

Naming Polyatomic anions Oxoanions Per... ate... ate... ite hypo... ite Increasing O content NO 3 - and NO 2 - ClO 4 - and ClO 3 - and ClO 2 - and ClO -

Ionic Compounds Composed of ions but neutral Na + and Cl - Ca 2+ and CO 3 2- Ca 2+ and Cl - Ti 4+ and O 2-

Electrostatic Forces - Coulomb’s Law

As ion charge increases, the attractive force _____. As the distance between ions increases, the attractive force ____.

Importance of Coulomb’s Law NaCl Na + and Cl -, m.p. 804 o C MgO Mg 2+ and O 2- m.p o C

Is a compound ionic? 1. Most metal-containing compounds are ionic. 2. Likely non-ionic if no metals 3. Look for polyatomic molecules like NH Ammonium ion IS NOT an ionic compound, but can be used to form an ionic compound