ION QUIZ

Today you will need your periodic table/ion sheet and your packet Warmup (3 minutes) What is a valence electron? Draw the Lewis dot structures of magnesium and fluorine. What does the term “neutral” mean (in terms of math and science)?

Is the red guy a cation or an anion? Is the red guy a metal or a nonmetal? Chemistry puts the "cation" in education. What's a cation afraid of? A dogion!

Ion: An atom (or group of atoms) that has lost or gained e- to follow the Octet Rule and is now electrically charged Metal atoms lose e- to form positive ions called cations: K+ Ca 2+ NH4+ Nonmetal atoms gain e- to form negative ions called anions: Cl- S2- CO32- Superscript written to the upper right shows the charge If the charge is +1 or -1, you don’t have to include the “1” Called an “oxidation number” Mg2+ F-

Write the (reduction) equation showing how flourine becomes an ion Ionization F + e-  F- Neutral but unstable fluorine atom, F Same # electrons as neon, but NOT an atom of neon! Write the (oxidation) equation showing how magnesium becomes an ion Mg  Mg2+ + 2e- Same # e- as…which element?

What patterns do you see? Are there any exceptions to these patterns? 1A metals: +1 ions 2A metals: +2 ions 7A nonmetals: -1 ions 6A nonmetals: -2 ions

Special ions (refer to handout) Some transition metals lose different numbers of electrons when they become ions They can have different charges as a cation, and must be written with roman numerals representing their charge (exception: Al3+) Examples? Polyatomic ions: group of more than one atoms with a charge (+ or -) Example: Why do chemists like nitrates so much? They're cheaper than day rates.

Ionic Bonds Na+ Cl- Nonmetal atoms remove e- from metal atoms. The two atoms become oppositely charged ions that attract each other, resulting in an ionic bond. An ionic compound forms. Cl- Read through EX 1 on “Writing and Naming Ionic Compounds” Handout that shows the crisscross method.

another example: iron(II)phosphate Fe2+ PO43- Fe2(PO4)3 NOOOOOOO! EX 2: Write the formula for the ionic compound calcium oxide Step 1: Write each ion with the correct charge. Look at periodic table group or cheat sheet for help. Ca2+ O2- Step 2: “Criss-cross” number associated with each charge (do not include the + or -) Ca2O2 Step 3: Remove any subscripts of 1. Eliminate both subscripts if they are the same. Write the formula. CaO EX 3: Write the formula for the ionic compound aluminum carbonate Al3+ CO32- Al2CO33 ???? Al2(CO3)3 another example: iron(II)phosphate Fe2+ PO43- Fe2(PO4)3 NOOOOOOO! Fe3(PO4)2

PO43- Fe 2+ Fe 2+ PO43- Fe 2+ 6- 6+ Ionic compounds aren’t present as individual molecules, they exist as large crystals with many many of the same ions. The subscripts show the RATIOS of the two ions --- one formula unit of this compound has 3 iron(II)’s and 2 phosphates. Fe 2+ Fe 2+ Fe 2+ PO43- PO43- PO43- PO43- 3:2 is simplified from 6:4 or 30,000:20,000 Fe 2+ Fe 2+ Fe 2+

Name  Formula potassium nitride copper (I) bromide potassium phosphide magnesium fluoride K3N CuBr K3P MgF2

Name these 2 compounds: CoS Figure out which ions form the compound because the ion charge could be important. Since S forms S2-, Co must be Co2+ b. Name the ions, cation first, then anion c. Change ending to –ide if it’s a pure element. cobalt (II)sulfide d. Transition metals always get a roman numeral to indicate their charge! Na2SO3 sodium sulfite Common mistakes: sodium(II)sulfite sodium(I)sulfite sodium sulfide/sulfate

Formula  Name Na2O CuS LiBr CuCl Sodium Oxide Copper (II) Sulfide Lithium Bromide Copper (I) Chloride

Name  Formula Ammonium Phosphate Iron (II) Nitrate Sodium Sulfate Silver Acetate (NH4)3PO4 Fe(NO3)2 Na2SO4 AgC2H3O2

Formula  Name Fe(OH)3 Mg(NO2)2 NiCO3 Cd(HCO3)2 Iron (III) Hydroxide Magnesium Nitrite Nickel (II) Carbonate Cadmium (II) hydrogen carbonate or Cadmium (II) bicarbonate

Name  Formula Sodium Dichromate Tin (II) Chromate Magnesium Permanganate lead (IV) bisulfate Na2Cr2O7 SnCrO4 Mg(MnO4)2 Pb(HSO4)4

Work on your packet! Make sure you have the Precipitation Lab with you next class!