Compounds Ionic Compounds (Page 7 in notes.we skipped it intentionally last day) All are solids at SATP (Standard Ambient Temperature and Pressure) of 25 o C and 100 kPa. When they dissolve in water, they form aqueous solutions that: are colored or colorless conduct electricity ie. they are electrolytes (show examples) Ionic Compounds These compounds form after an electron transfer: usually from a metal to a nonmetal the resulting ions (cations and anions) are attracted to each other (since they are oppositely charged) and they form ionic bonds Start to draw Sodium chloride example on board. Stop before writing compound Ionic Compounds Together all of the ions present form an ionic crystal lattice in which the net charge is zero Ionic Compounds Eg: (1) in a sample of sodium chloride, NaCl, for every Na + ion there is one Cl- ion Eg (2) in a sample of calclium chloride, CaCl 2, for every Ca 2+ ion there are 2 Cl- ions Formula Unit:an expression of the simplest whole number ratio of cations to anions Complete Examples on Board (Sodium Chloride and Calcium Chloride) extra page? Writing Empirical Formulas for Ionic Compounds (Page 8) Empirical formulas show the ratios of different ions found in an ionic compound. Example: Compound: KCl (Potassium Chloride) Ratio: one K+ : one Cl- Emperical Formula: K 1 Cl 1 is the same as KCl Even though a sample of potassium chloride has trillions and trillions each ion, we write the formula as the smallest possible ratio, which is 1:1 General Rules (of writing formulas) 1. Write each ion symbol with charge. 2. Determine # of +ve and ve ions needed to create a compound with a balanced charge. Total positive charge = total negative charge. 3. Assign subscripts to each ion (subscript indicates the number of that ion present in the formula). 4. Re-write the symbol of each ion with subscript. Do not include ion charges in final formula. Writing Empirical Formulas for Ionic Compounds Heed the Note section on the top of page 9 Examples: Monatomic: Silver chloride and Aluminum Oxide Polyatomic: Potassium carbonate and ammonium nitrate Multivalent: Iron(II) sulfide and Lead(IV) oxide Hydrate: Zinc chloride hexahydrate and Copper(II)sulphate pentahydrate Worksheets 8-11 Complete the first half of each section before completely finishing any worksheet! This is so you encounter a variety of problems now while I can help you. Quiz #1