Electrolytes and Nonelectrolytes. Electrolytes and Nonelectrolytes. Electrolytes. Nonelectrolytes

Transcription

1 Chapter Chemical Compounds Ionic and Molecular Compounds Monatomic and Polyatomic Ions Formulas for Ionic Compounds Naming Ionic Compounds Naming and Writing Formulas for Molecular Compounds Acids and Bases Predicting Properties and Naming Compounds 1 Copyright The McGrawHill Companies, Inc. Permission required for reproduction or display. Electrolytes and Nonelectrolytes Electrolytes substances that release ions when dissolved in water This process is also called dissociation or ionization conduct electricity Nonelectrolytes substances that do NOT dissociate in water do NOT conduct electricity Example: methanol 2 Electrolytes and Nonelectrolytes 1

2 Strong and Weak Electrolytes Strong electrolytes dissociate completely into ions in water conduct electricity well Examples: NaCl and HCl Weak electrolytes do not dissociate completely into ions in water do not conduct electricity well Example: acetic acid 4 Strong and Weak Electrolytes 5 Ionic Compounds Are composed of a metal cation and a nonmetal anion Metals cations are positively charged ions Nonmetals anions are negatively charged ions Their cations and anions exist in proportions that give electrical neutrality These ions are arranged in a crystal lattice Also called salts Are one of the major categories of chemical compounds 6 2

3 Ionic Compounds Figure.8 7 Molecular Compounds Are composed of 2 or more nonmetals Have no overall charge Are the other major category of chemical compounds 8 Table.1 Ionic and Molecular Compounds Properties of Ionic and Molecular Compounds Ionic Compounds Molecular Compounds Crystalline solid Gas, liquid, or solid Hard, brittle solid Very high melting point Very high boiling point High density Strong electrolyte in aqueous solution Electrical conductivity is good when compound is molten Soft solid Low melting point Low boiling point Low density Weak or nonelectrolyte in aqueous solution Electrical conductivity poor in pure form 9

4 Practice Ionic and Molecular Compounds Based on their formulas, which of the following are ionic compounds? Which are molecular compounds? 1. O 2 2. CaO. Na N 4. NF Which of the following compounds has a higher boiling point? 1. KCl or CCl 4 2. SO or Na 2 SO 4. Cu PO 4 or P 4 O Practice Solutions Ionic and Molecular Compounds Based on their formulas, which of the following are ionic compounds? Which are molecular compounds? 1. O 2 molecular compound 2. CaO ionic compound. Na N ionic compound 4. NF molecular compound 11 Practice Solutions Ionic and Molecular Compounds Which of the following compounds has a higher boiling point? 1. KCl or CCl 4 KCl (ionic compounds have high boiling points) 2. SO or Na 2 SO 4 Na 2 SO 4. Cu PO 4 or P 4 O 10 Cu PO

5 Monoatomic Ions Are ions of a single atom Many are shown below on Figure.12 and Table.2 Most maingroup elements tend to form their ion charge based on how far away their group is from the noble gases Transition metals tend to form multiple charges 1 Polyatomic Ions An ion containing 2 or more atoms, usually of more than one element The most common are oxoanions, anions that contain oxygen attached to another element. Many are shown below on Figure.17 and Table.4 One polyatomic cation NH Table.4 Important Polyatomic Anions Ions with a 1 charge Nitrate Nitrite NO NO 2 Bicarbonate HCO Perchlorate ClO 4 Chlorate ClO Chlorite ClO 2 Hypochlorite ClO Cyanide CN Hydroxide OH Acetate C 2 H O 2 Permanganate MnO 4 Ions with a 2 charge Chromate Dichromate Cr 2 O 2 7 Sulfate Sulfite Carbonate SO 2 4 SO 2 CO 2 Oxalate C 2 O 2 4 Peroxide Phosphate Phosphite Borate CrO 4 2 O 2 2 Ions with a charge PO 4 PO BO 15 5

6 Writing Formulas for Ionic Compounds When writing a formula for an ionic compound, the sum of the positive charges must equal the sum of the negative charges. Total positive charge + total negative charge = zero net charge from cations from anions The crystal structures or lattices are composed of repeating units called formula units. 16 Practice Writing Ionic Formulas Write the formulas for compounds containing the following ions: 1. Calcium ion and nitride ion 2. Barium ion and nitrate ion. Potassium ion and sulfate ion 17 Practice Solutions Writing Ionic Formulas Write the formulas for compounds containing the following ions: 1. Calcium ion and nitride ion Ca 2+ N The least common denominator between +2 and is 6. Therefore, this compound needs calcium ions for every 2 nitride ions. Answer: Ca N 2 2. Barium ion and nitrate ion Ba 2+ NO The least common denominator between +2 and 1 is 2. Therefore, this compound needs 1 barium ion for every 2 nitrate ions. Answer: Ba(NO )

7 Practice Solutions Writing Ionic Formulas Write the formulas for compounds containing the following ions:. Potassium ion and sulfate ion K + SO 4 2 The least common denominator between +1 and 2 is 2. Therefore, this compound needs 2 potassium ions for every 1 sulfate ion. Answer: K 2 SO 4 19 Practice Naming Ionic Compounds Now that you have translated the ion names into an ionic formula, translate the formula into the ion names. 1. NaCl 2. NaNO 2. MgCl 2 4. Mg(NO ) 2 5. BaO 6. Li N 20 Practice Solutions Naming Ionic Compounds Now that you have translated the ion names into an ionic formula, translate the formula into the ion names. 1. NaCl sodium ion and chloride ion (name: sodium chloride) Na + and Cl 2. NaNO 2 sodium ion and nitrite ion (name: sodium nitrite) Na + and NO 2. MgCl 2 magnesium ion and chloride ion (name: magnesium chloride) Mg 2+ and Cl 21 7

8 Practice Solutions Naming Ionic Compounds Now that you have translated the ion names into an ionic formula, translate the formula into the ion names. 4. Mg(NO ) 2 magnesium ion and nitrate ion (name: magnesium nitrate) 5. BaO barium ion and oxide ion (name: barium oxide) 6. Li N lithium ion and nitride ion (name: lithium nitride) 22 Naming Ionic Compounds Naming metals Monatomic cations are named according to the periodic table Transition metals (and Sn and Pb) require a Roman numeral in parenthesis to designate their charge (using the Stock System) MainGroup Do nothing more Metals according to periodic table Transition Write Roman numeral telling charge 2 Naming Ionic Compounds Naming nonmetals Monatomic anions 1. according to the periodic table 2. Drop the ending. Add an ide Polyatomic anions according to the Polyatomic Ion Chart (Table.4) Monatomic Drop ending and add ide Nonmetals Polyatomic according to Table

9 Naming Ionic Compounds Summary Main Group Metals 25 Naming Ionic Compounds Summary Transition Metals NH Common s for Metals with Variable Charges An older naming system exists for transition metals (and Sn and Pb) based on the roots of the original Latin names. The smaller charge has an ous ending. The larger charge has an ic ending. 27 9

10 Common s for Metals with Variable Charges Table.7 s of Ionic Compounds Containing Metals with Variable Charges Compound Ion Stock Old FeCl 2 Fe +2 iron(ii) chloride ferrous chloride FeCl Fe + iron(iii) chloride ferric chloride Cu 2 O Cu +1 copper(i) oxide cuprous oxide CuO Cu +2 copper(ii) oxide cupric oxide SnO Sn +2 tin(ii) oxide stannous oxide SnO 2 Sn +4 tin(iv) oxide stannic oxide 28 Practice Naming Molecular Compounds s of Some Common Molecular Compounds Formula CO CO 2 CCl 4 carbon monoxide carbon dioxide carbon tetrachloride Formula SO N 2 O 4 PF 5 sulfur trioxide dinitrogen tetroxide phosphorus pentafluoride Do you see the pattern? Try naming these compounds as well. 1. SO 2 2. NF. P 4 O Practice Solutions Naming Molecular Compounds s of Some Common Molecular Compounds Formula CO CO 2 CCl 4 carbon monoxide carbon dioxide carbon tetrachloride Formula SO N 2 O 4 PF 5 sulfur trioxide dinitrogen tetroxide phosphorus pentafluoride Try naming these compounds as well 1. SO 2 sulfur dioxide 2. NF nitrogen trifluoride. P 4 O 10 tetraphosphorus decoxide 0 10

11 Naming Molecular Compounds We will name binary molecular compounds Binary Compounds A compound containing atoms or ions of only two elements To name molecular compounds, we: 1. the leftmost element as we would a maingroup metal according to the periodic table. 2. the rightmost element as we would a monatomic anion drop the ending of the name (from the periodic table) and add an ide.. Use Greek prefixes to denote the number of atoms of each element. 1 Naming Molecular Compounds Table.9 Common Greek Prefixes Prefix Prefix mono 1 hexa 6 di 2 hepta 7 tri octa 8 tetra 4 nona 9 penta 5 deca 10 2 Naming Molecular Compounds Summary 11

12 Acids and Bases Acids Are substances that when dissolved in water provide hydrogen ions (H + ) An example of the dissociation (or ionization) of an acid: H 2 O HCl(g) H + (aq) + Cl (aq) Bases Are substances that react with acids in aqueous solution to form water An example of the ionization of a base: H NaOH(s) 2 O Na + (aq) + OH (aq) 4 Naming Acids Table.11 s of Some Common Acids Formula HF(aq) HCl(aq) HI(aq) H 2 S(aq) H 2 CO (aq) HNO (aq) Hydrofluoric acid Hydrochloric acid Hydroiodic acid Hydrosulfuric acid Carbonic acid Nitric acid Formula H 2 SO 4 (aq) H 2 SO (aq) HClO 4 (aq) HClO (aq) HClO 2 (aq) HClO(aq) Sulfuric acid Sulfurous acid Perchloric acid Chloric acid Chlorous acid Hypochlorous acid 5 Naming Acids Since most acids have a hydrogen as their 1 st element in the molecular formula, the acids are named according to the anion, not the cation (H + ). Binary acids are named as hydro followed by the root of the element (2 nd element or anion) name with an ic suffix and the word acid placed at the end of the name. Acids containing polyatomic ions (as the anion) are named by taking the root of the polyatomic ion name, replacing ate with ic or replacing ite with ous and adding the word acid at the end. 6 12

13 Naming Acids Summary 7 Practice Naming Molecular Compounds the following binary molecular compounds: 1. OF 2 2. SiCl 4. P 4 O 6 the following acids: 1. HBr(aq) 2. HMnO 4 (aq). H PO (aq) 8 Practice Solutions Naming Molecular Compounds the following binary molecular compounds: 1. OF 2 oxygen difluoride 2. SiCl 4 silicon tetrachloride. P 4 O 6 tetraphosphorus hexoxide the following acids: 1. HBr(aq) hydrobromic acid 2. HMnO 4 (aq) permanganic acid. H PO (aq) phosphoric acid 9 1

14 Naming Compounds Summary 40 Naming Compounds Summary Type of Compound Ionic Molecular Acids Naming Cation named first followed by anion 1 st atom in formula (the element farther down or to the left in the periodic table) named 1 st with the second element named as if it were an anion. Greek prefixes are used to designate the number of atoms in a molecule. Binary acids are named as hydro followed by the root of the element name with an ic suffix and the word acid placed at the end of the name. Acids containing polyatomic ions are named by taking the root of the polyatomic ion name, replacing ate with ic or replacing ite with ous and adding the word acid at the end. 41 Practice Naming Compounds the following compounds: 1. Al 2 S 2. HNO 2 (aq). HI(aq) 4. P 2 O 5 5. Cu(OH) 2 6. H 2 SO (aq) 7. K 2 O 8. CS 2 9. (NH 4 ) 2 CO 10. Fe(C 2 H O 2 ) 42 14

15 Practice Solutions Naming Compounds the following compounds: 1. Al 2 S aluminum sulfide 2. HNO 2 (aq) nitrous acid. HCl(aq) hydrochloric acid 4. P 2 O 5 diphosphorus pentoxide 5. Cu(OH) 2 copper(ii) hydroxide 6. H 2 SO (aq) sulfurous acid 7. K 2 O potassium oxide 8. CS 2 carbon disulfide 9. (NH 4 ) 2 CO ammonium carbonate 10. Fe(C 2 H O 2 ) iron(iii) acetate 4 Practice Naming Compounds Write the compound formulas for the following names: 1. Lead(II) chloride 2. Magnesium phosphate. Nitrogen triiodide 4. Hydrofluoric acid 5. Tin(IV) oxide 6. Calcium nitride 7. Cyanic acid 8. Dichlorine pentoxide 9. Sodium hydrogen carbonate 10. Hydrogen peroxide 44 Practice Solutions Naming Compounds Write the compound formulas for the following names: 1. Lead(II) chloride PbCl 2 2. Magnesium phosphate Mg (PO 4 ) 2. Nitrogen triiodide NI 4. Hydrofluoric acid HF(aq) 5. Tin(IV) oxide SnO 2 6. Calcium nitride Ca N 2 7. Cyanic acid HCN(aq) 8. Dichlorine pentoxide Cl 2 O 5 9. Sodium hydrogen carbonate NaHCO 10. Hydrogen peroxide H 2 O