NAMING IONIC COMPOUNDS

Transcription

1 NAMING IONIC COMPOUNDS There are a few general rules that apply when naming ionic compounds. 1. Most ionic compounds are also called salts. 2. Most ionic compounds exist as solids and many dissolve to form aqueous solutions. 3. An ionic compound is made up of a metal and a nonmetal; metals are located on the left side of the periodic table and nonmetals are on the right side. 4. The cation (positive ion) is written first followed by the anion (negative ion). 5. Before naming compounds, you should first memorize the individual cations and anions.

2 Writing Chemical Formulas 1. The charge of the individual ions in a salt should add up to zero, the overall charge of the compound. For example NaCl is composed of Na+ ions and Cl- ions. For every one sodium ion you need one chloride ion (+1) + (-1) = 0 Ba 2+ and N 3- : You need 3 (+2 ) Barium ions to cancel out the 2 (-3) nitride ions so the overall charge of the compound is zero. 2. The individual ions should add up to the overall charge of the polyatomic ion. What is the charge of Mn in MnO 4 -? 1 Mn + 4 O = -1 so 1(Mn) + 4 (-2) = -1 so Mn - 8 = -1 so Mn = +7

3 Nomenclature of binary ionic compounds Symbol Element Root Anion Symbol Anion Name Br Bromine Brom Br - Bromide Cl Chlorine Chlor Cl - Chloride F Fluorine Fluor F - Fluoride H Hydrogen Hydr H - Hydride I Iodine Iod I - Iodide N Nitrogen Nitr N -3 Nitride O Oxygen Ox O -2 Oxide P Phosphorus Phosph P -3 Phosphide S Sulfur Sulf S -2 Sulfide

4 Nomenclature of binary ionic compounds Name the metal then the root of the nonmetal + ide ending: Sodium chloride Barium chloride NaCl BaCl 2 H 2 S Hydrogen sulfide Mg 3 N 2 NaF Sodium fluoride K 2 O Magnesium nitride Potassium oxide Notice that the cation is always mentioned first and then the anion. Notice that the anion always ends in -ide Notice that the number of elements in the compound is not mentioned in the name. Name the following ionic compounds: Na 2 O K 2 S MgBr 2 AlN Ba 3 As 2 CaCl 2 AgCl AlH 3 ZnI 2 Li 3 P

5 Nomenclature of binary ionic compounds Answers: Na 2 O = sodium oxide K 2 S = potassium sulfide MgBr 2 = magnesium bromide AlN = aluminum nitride Ba 3 As 2 = barium arsenide CaCl 2 = calcium chloride AgCl = silver chloride AlH 3 = aluminum hydride ZnI 2 = zinc iodide Li 3 P = lithium phosphide

6 Nomenclature of binary ionic compounds Some polyatomic anions that you must know: NO 3- = nitrate NO 2- = nitrite SO 2-4 = sulfate SO 2-3 = sulfite PO 3-4 = phosphate PO 3-3 = phosphite CO 2-3 = carbonate HCO 1-3 = hydrogen carbonate or bicarbonate OH - = hydroxide CN - = cyanide C 2 H 3 O - 2 = acetate C 2 O 2-4 = oxalate

7 Nomenclature of binary ionic compounds Naming salts composed of the polyatomic ions is the same as with the monatomic anions. Metal name then polyatomic name. NaOH sodium hydroxide Ba(NO 3 ) 2 barium nitrate H 2 SO 4 hydrogen sulfate CsNO 2 cesium nitrite Sometimes there is a common name: KHCO 3 potassium hydrogen carbonate or potassium bicarbonate Note: the polyatomic anions must be memorized. Name the following ionic compounds: NaHCO 3 K 2 SO 3 MgSO 4 KCN H 2 PO 4 Ca(OH) 2 NH 4 NO 3 Zn(NO 3 ) 2 Li 3 PO 4 HNO 3

8 Nomenclature of binary ionic compounds Answers: NaHCO 3 K 2 SO 3 MgSO 4 KCN H 2 PO 4 Ca(OH) 2 NH 4 NO 3 Zn(NO 3 ) 2 Li 3 PO 4 HNO 3 = sodium hydrogen carbonate or sodium bicarbonate = potassium sulfite = magnesium sulfate = potassium cyanide = hydrogen phosphate = calcium hydroxide = ammonium nitrate = zinc nitrate = lithium phosphate = hydrogen nitrate

9 Early Names of Elements Present Name Symbol Former Name Antimony Sb Stibium Copper Cu Cuprum Gold Au Aurum Iron Fe Ferrum Lead Pb Plumbum Mercury Hg Hydrargyrum Potassium K Kalium Silver Ag Argentum Sodium Na Natrium Tin Sn Stannum Tungsten W Wolfram

10 Nomenclature of binary ionic compounds The previous examples only named type 1 or fixed oxidation state cations. When naming type 2 or variable oxidation state cations the rules change. CuOH copper(i) hydroxide Fe(NO 3 ) 3 iron(iii) nitrate CuSO 4 copper(ii) sulfate Sn(NO 2 ) 4 tin(iv) nitrite Sometimes a common name exists: CuOH cuprous hydroxide Fe(NO 3 ) 3 ferric nitrate When naming type 2 cations, the systematic method (IUPAC) requires the use of roman numerals after the elemental name to represent the oxidation state of the cation. The common name uses the ic ending for the higher oxidation state and ous ending for the lower oxidation state. Many times the old latin or greek name is used as the root. Name the following ionic compounds: CuHCO 3 FeSO 3 CuSO 4 Cr(CN) 3 Cr(PO 4 ) 2 Sn(OH) 2 W(NO 2 ) 5 Ti(CO 3 ) 2 CoPO 4 PbCl 2

11 Nomenclature of binary ionic compounds Answers: CuHCO 3 = copper(i) hydrogen carbonate or cuprous bicarbonate FeSO 3 = iron(ii) sulfite or ferrous sulfite CuSO 4 = copper(ii) sulfate or cupric sulfate Cr(CN) 3 = chromium(iii) cyanide Cr(PO 4 ) 2 = chromium (VI) phosphate Sn(OH) 2 = tin(ii) hydroxide or stannous hydroxide W(NO 2 ) 5 = tungsten(v) nitrite Ti(CO 3 ) 2 = titanium(iv) carbonate CoPO 4 = cobalt(iii) phosphate or cobaltic phosphate PbCl 2 = lead(ii) chloride or plumbous chloride

12 PRACTICE PROBLEMS # 9a Below the formula, give the systematic name for the following compounds. If a common name exist, write it below the systematic name. 1. KBr 2. BaO 3. Na 2 O potassium bromide Barium oxide Sodium oxide 4. BiF 3 5. Cr 2 S 3 6. Ti(NO 3 ) 4 Bismuth (III) fluoride Chromium (III) sulfide The problem set continues on the next page. Titanium (IV) nitrate or titanic nitrate

13 GROUP STUDY PROBLEM # 9a Below the formula, give the systematic name for the following compounds. If a common name exist, write it below the systematic name. 1. CaI 2 2. Cs 2 S 3. Al 2 S 3 4. CdI 2 5. SnCl 2 6. Zn(NO 3 ) 2 7. Fe 2 O 3 8. Fe(OH) 2 9. PbSO 4 The problem set continues on the next page.

14 PRACTICE PROBLEMS #9b Below the name, write the formula for the following compounds. Lithium chloride b) Aluminum sulfide e) Copper(II) oxide Li f) + Cl - Al 3+ S 2- LiCl Iron(III) chloride i) Al 2 S 3 Calcium bicarbonate l FeCl 3 Ca(HCO 3 ) 2 CuO Potassium nitrite Potassium perchlorate KNO 2 KClO 4 Ammonium carbonates s )Iron(II) phosphate w) (NH 4 ) 2 CO 3 Fe 3 (PO 4 ) 2

15 GROUP STUDY PROBLEM #9b Below the name, write the formula for the following compounds. a) Barium oxide b) Sodium bromide c) Copper(I) oxide d) Iron(II) chloride e) Potassium nitrite f) Calcium hydroxide g) Silver nitrate h) Ammonium chloride i) Lithium phosphate j) Sodium nitrite k) Sodium bicarbonate l) Calcium Carbonate m) Sodium sulfate n) Iron(III) hydroxide o) Copper(II) hypochlorite p) Sodium sulfite