Naming Ionic Compounds, Cations and Anions "What's in a name? That which we call a rose, by any other name, would smell as sweet." Romeo and Juliet (II, ii, 1-2)
COMPOUNDS FORMED FROM IONS Na+ + Cl- NaCl CATION + ANION COMPOUND A neutral compound requires equal number of (+) and (-) charges. Let’s learn how to name the ions. Then, we can name their compounds.
Ionic Naming Practice NaCl CaCl 2 MgO Al 2 O 3 FeBr 2 CuCl SnO 2 Fe 2 O 3 Hg 2 S Sodium chloride Calcium chloride Magnesium oxide Aluminium oxide Iron (II) Bromide Copper (I) Chloride Tin (IV) Oxide Iron (III) Oxide Mercury (II) Sulfide [notice the subscript number under the oxygen = the number for Iron’s Roman Numerals]
Ionic Naming Warm Up NaBr BeCl 2 K 2 O Al 2 S 3 AgBr 2 CdCl 2 SnO FeO CuS Sodium bromide Beryllium chloride Potassium oxide Aluminium sulfide Silver Bromide Cadmium (II) Chloride Tin (II) Oxide Iron (II) Oxide Copper (II) Sulfide
1. Cation first, then anion 2. Monatomic cation = elemental name Ca 2+ = calcium ion 3. polyatomic anion = name of polyatomic CO32 = carbonate Thus CaCO3 = calcium carbonate Overview of Naming Ternary Ionic Compounds: Take Home Message: Same method as with binary ionics except a polyatomic anion is in place of the monatomic anion!
Ternary Ionic Formulas Calcium Sulfate Ca2+ and SO4-2 CaSO4 Iron (III) hydroxide Fe+3 and OH- Fe(OH)3 Ammonium carbonate NH4+ and CO3–2 (NH4)2CO3 The (2+) and (2-) charges cancel each other out So, we need one of each The (3+) needs (3-) to cancel but OH is only a (1-) So, we need three OH ions The (2-) needs (2+) to cancel but NH4 is only a (1+) So, we need two NH4 ions
Learning Check 1. aluminum nitrate a) AlNO3 b) Al(NO)3 c) Al(NO3)3 2. copper (II) nitrate a) CuNO3 b) Cu(NO3)2 c) Cu2(NO3) 3. Iron (III) hydroxide a) FeOH b) Fe3OH c) Fe(OH)3 4. Tin (IV) hydroxide a) Sn(OH)4 b) Sn(OH)2 c) Sn4(OH)
1. Cation first, then anion 2. Monatomic cation = elemental name calcium = Ca2+ 3. monatomic anion = “-ide” name sulfide = S2- Thus calcium sulfide = CaS Overview of Formula Writing Steps: Take Home Message: It’s just that easy! But, beware the charge balance!!!!!!
You Try it: Write these out on your notes Write the formula: Potassium bromide Barium fluoride Copper (II) oxide Calcium nitride Aluminum carbonate Beryllium hydroxide KBr K+ & Br- BaF2 Ba2+ & F- CuO Cu2+ & O2- Ca3N2 Ca2+ & N3- Al2(CO3)3 Al3+ & CO32- Be(OH)2 Be2+ & OH- *Notice any relationship between the charges of the anions and the subscripts on the cations? Vice-versa?