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Naming and Writing Formulas for Ionic Compounds

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Objectives 1.Name and write the symbols for common anions, cations, and polyatomic ions. 2.Determine the formula of an ionic compound between any two given ions. 3.Name ionic compounds, given their formulas. 4.Correctly use Roman numerals when naming compounds containing transition metals with more than one oxidation number. 5.Write formulas for ionic compounds, given their names. Back to main menu

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Naming and Writing Formulas for Ionic Compounds In forming a chemical compound, an atom can gain, lose or share one or more valence electrons. Back to main menu

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Positive Ions A cation is an atom or group of atoms with a positive charge. A cation has fewer electrons than a neutral atom of the element. Back to main menu

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Symbols of Ions for Cations The metals in groups 1, 2 and 13 lose electrons when they form ions. Group 1 forms +1 ions. Group 2 forms +2 ions Group 13 forms +3 ions. Back to main menu

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Naming and Writing Symbols for Cations Back to main menu ElementSymbol of IonName of Ion Calcium Sodium Aluminum Ca 2+ Calcium ion Na + Sodium ion Al 3+ Aluminum ion

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Metals with More than One Common Oxidation Number The metals in groups 3-12 are called transition metals. They often have more than one common oxidation number (ionic charge). Back to main menu

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Metals with More than One Common Oxidation Number Here are some of the more commonly used transition metals and their oxidation numbers. Notice that a Roman numeral is used to indicate the charge on the ion when naming the ions formed. Back to main menu Fe 2+ Iron(II) ionFe 3+ Iron(III) ion Cu + Copper(I) ionCu 2+ Copper(II) ion Hg 2 2+ Mercury(I) ionHg 2+ Mercury(II) ion Pb 2+ Lead(II) ionPb 4+ Lead(IV) ion Sn 2+ Tin(II) ionSn 4+ Tin(IV) ion Cr 2+ Chromium(II) ionCr 3+ Chromium(III) ion Cr 6+ Chromium(VI) ion Mn 2+ Manganese(II) ionMn 3+ Manganese(III) ion Co 2+ Cobalt(II) ionCo 3+ Cobalt(III) ion Ni 2+ Nickel(II) ionNi 3+ Nickel(III) ion Ag + Silver ion Zn 2+ Zinc ion Cd 2+ Cadmium ion

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Negative Ions An anion is an atom or group of atoms with a negative charge. An anion has more electrons than a neutral atom of the element. Group 17 forms -1 ions. Group 16 forms -2 ions. Group 15 forms -3 ions. The names of monatomic anions end in ide. Back to main menu

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Naming and Writing Formulas for Anions Back to main menu ElementSymbol of IonName of Ion Chlorine Nitrogen Oxygen Cl - Chloride ion N 3- Nitride ion O 2- Oxide ion

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You Try It Complete the following table. S 2- Back to main menu Symbol of Ion Name of IonNumber of Electrons Lost or Gained Sulfide ion Cu + Barium ion Al 3+ Iron(III) ion Li + Phosphide ion 2 e - gained Copper(I) ion 1 e - lost Ba 2+ 2 e - lost Aluminum ion 3 e - lost Fe 3+ 3 e - lost Lithium ion 1 e - lost P 3- 3 e - gained

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Predicting Formulas of Ionic Compounds Ionic compounds are composed of charged particles called ions. They are electrically neutral. This means that the total positive charge is equal to the total negative charge. Binary ionic compounds usually consist of a metal, such as an alkali metal, bonded to a nonmetal, such as a halogen. Empirical formulas are used to represent ionic compounds. An empirical formula is the simplest ratio in which the atoms combine to form a compound. Back to main menu

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Predicting Formulas of Ionic Compounds Examples: Write the formulas for the compounds formed between the following pairs of ions. Back to main menu a. K +, Cl - b.Mg 2+, S 2- c.Na +, S 2- d.Al 3+, S 2- e.Sn 4+, O 2- KCl MgS Na 2 S Al 2 S 3 SnO 2

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You Try It Write the formulas for the following binary ionic compounds. Hint: First determine the symbols for the ions involved. Always write the cation first. The first one has been done for you as an example. Back to main menu a.Sodium bromide b.Magnesium sulfide c.Copper(I) chloride d. Calcium bromide e.Strontium fluoride Na +, Br - Mg 2+, S 2- Cu +, Cl - Ca 2+, Br - Sr 2+, F - NaBr MgS CuCl CaBr 2 SrF 2

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You Try It Write the formulas for the following binary ionic compounds. Hint: First determine the symbols for the ions involved. Always write the cation first. The first one has been done for you as an example. Back to main menu f.Sodium oxide g.Lead(II) bromide h.Zinc sulfide i.Aluminum oxide j.Chromium(VI) nitride Na +, O 2- Pb 2+, Br - Zn 2+, S 2- Al 3+, O 2- Cr 6+, N 3- Na 2 O PbBr 2 ZnS Al 2 O 3 CrN 2

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Naming Binary Ionic Compounds Binary ionic compounds are named by writing the name of the cation followed by the name of the anion (-ide ending). Back to main menu a.Na 2 S b.LiF c.BaCl 2 Sodium sulfide Lithium fluoride Barium chloride

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Roman Numerals Sometimes it is necessary to use a Roman numeral when naming an ionic compound. Back to main menu When do you use a Roman numeral when naming an ionic compound? You use a Roman numeral when the metallic element forms more than one common ion. This is common of the transition metals. CuCl is CuCl 2 is Copper(I) Chloride Copper(II) Chloride

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Roman Numerals Never use a Roman numeral when the metallic element is from Group 1, Group 2, or for aluminum, cadmium, zinc or silver. Back to main menu Circle the compounds below that would need a Roman numeral when naming them. SnCl 2 Fe 2 O 3 BaCl 2 LiF MgS CaO SrF 2 CoI 3

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Roman Numerals How do I determine the charge of the Roman numeral? Back to main menu To determine the charge of the Roman numeral you have to first identify the ions making up the compound.

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Roman Numerals Examples. Back to main menu Fe 2 O 3 Iron(III) oxide Ions Chemical Formula Name of Compound Fe 3+, O 2- Cu +, S 2- CoI 2 Tin(IV) oxide FeS Cu 3 N Cu 2 SCopper(I) sulfide Co 2+, I - Cobalt(II) iodide Sn 4+, O 2- SnO 2 Fe 2+, S 2- Iron(II) sulfide Cu +, N 3- Copper(I) nitride

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You Try It Write formulas for the following compounds. Remember to determine the ions involved first. Back to main menu Name of CompoundIons Formula of Compound Lithium oxide Tin(IV) sulfide Barium nitride Sodium fluoride Li 2 OLi +, O 2- Sn 4+, S 2- SnS 2 Na +, F - Ba 2+, N 3- Ba 3 N 2 NaF

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You Try It Name the following compounds. Back to main menu a.CaS b.FeN c.K 2 O d.PbO Calcium sulfide Iron(III) nitride Potassium oxide Lead(II) oxide

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Naming and Writing Formulas for Ternary Ionic Compounds Ternary ionic compounds contain more than two elements. They usually contain one or more polyatomic ions. Back to main menu Common Polyatomic Ions 1 - Charge2 - Charge3 - Charge PerchlorateClO 4 - CarbonateCO 3 2- PhosphatePO 4 3- ChlorateClO 3 - SulfateSO 4 2- PhosphitePO 3 3- ChloriteClO 2 - SulfiteSO 3 2- HypochloriteClO - ChromateCrO 4 2 1 + Charge NitrateNO 3 - DichromateCr 2 O 7 2- AmmoniumNH 4 + NitriteNO 2 - OxalateC 2 O 4 2- IodateIO 3 - SilicateSiO 3 2- BromateBrO 3 - Hydrogen PhosphateHPO 4 2- PermanganateMnO 4 - HydroxideOH - CyanideCN - AcetateC2H3O2-C2H3O2- Dihydrogen phosphateH 2 PO 4 - Hydrogen Sulfite (bisulfate) HSO 3 - Hydrogen sulfate (bisulfate) HSO 4 - Hydrogen carbonate (bicarbonate) HCO 3 -

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Writing Formulas for Ternary Ionic Compounds Writing the formulas for ternary ionic compounds is just like writing the formula for binary ionic compounds. You write the symbol and charge of the ions involved and then balance the charges. Back to main menu

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Writing Formulas for Ternary Ionic Compounds Examples: Back to main menu a.K +, NO 3 - b.Ba 2+, PO 4 3- KNO 3 Ba 3 (PO 4 ) 2

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You Try It 1.Write the formulas for the following ternary ionic compounds, given the ions involved. Back to main menu a.Ca 2+, SO 4 2- b.K +, PO 4 3- c.NH 4 +, N 3- d.Al 3+, SO 4 2- CaSO 4 K 3 PO 4 (NH 4 ) 3 N Al 2 (SO 4 ) 3

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You Try It 2.Write the formulas for the following ternary ionic compounds given their names. Back to main menu Lithium hypochlorite Sodium sulfite Calcium acetate Barium phosphate Copper(II) nitrite LiClO Na 2 SO 3 Ca(C 2 H 3 O 2 ) 2 Ba 3 (PO 4 ) 2 Cu(NO 2 ) 2 Li +, ClO - Na +, SO 3 2- Ca 2+, C 2 H 3 O 2 - Ba 2+, PO 4 3- Cu 2+, NO 2 -

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You Try It 3.To name a compound, write the name of the cation followed by the name of the anion. Back to main menu a. Ca(NO 3 ) 2 b. K 2 SO 4 c. PbSO 3 d. NaC 2 H 3 O 2 e. (NH 4 ) 2 S Calcium nitrate Potassium sulfate Lead(II) sulfite Sodium Acetate Ammonium sulfide