Naming (1).pdf

Naming CHEM 1211 Ionic Compounds Ionic bonds are the chemical bonds that hold cations and anions together in an ionic compound. Formulas are balanced. – Total positive charge must equal total negative charge.  Naming Ionic Compounds Cation (positive...

Naming CHEM 1211 Ionic Compounds Ionic bonds are the chemical bonds that hold cations and anions together in an ionic compound. Formulas are balanced. – Total positive charge must equal total negative charge.  Naming Ionic Compounds Cation (positive Anion (negative charge) formed (1st) charge) formed (2nd) from metal from nonmetal Na2S sodium sulfide (add –ide ending to 3 nonmetal) Note: do not change the name of a polyatomic ion Sc3+ Zn2+ Ag+ Name to Formula- Ionic Example: aluminum oxide 1. Write the symbol for the metal cation and its charge. Al3+ 2. Write the symbol for the nonmetal anion and its charge. O2- 3. Charge (without sign) becomes subscript for other ion. Al2 O3 4. Reduce subscripts to smallest whole number ratio. Al2O3 5. Check that total positive charge cancels total negative charge. (2 x +3) + (3 x -2) = 0 Ionic Compounds Name the following compounds. 1. KCl potassium chloride 2. CaO calcium oxide 3. MgBr2 magnesium bromide Metals with Variable Charges Some metals form ions of different charges. Can use charge of anion to determine charge of cation. Roman numerals used in name to indicate charge. Rest of the naming rules are the same. Example: Au2S3 gold(III) sulfide Metals with Variable Charges Name the following: 1. TiCl4 titanium (IV) chloride 2. CrO3 chromium (VI) oxide 3. Fe3N2 iron (II) nitride Polyatomic Ions Single ions that contain multiple atoms. Name cation first, followed by anion. Example: NH4Cl ammonium chloride Example: Ba3(PO4)2 barium phosphate Polyatomic Ions Elements in the same group form similar polyatomic ions – ClO3 - = chlorate – BrO3- = bromate – IO3- = iodate If the polyatomic ion begins with H, add the prefix “hydrogen” before the name & increase charge by +1 – CO3 2- = carbonate – HCO3 - = hydrogen carbonate Polyatomic Ions Name the following compounds. 1. NH4OH ammonium hydroxide 2. Ca(C2H3O2)2 calcium acetate 3. Cu(NO3)2 copper (II) nitrate  Polyatomic Ions Formula Name Add 1 O ClO4- perchlorate Begin with –ate ion ClO3- chlorate Remove 1 O ClO2- chlorite Remove 2 O ClO- hypochlorite Hydrates Ionic compounds containing a specific number of water molecules for each formula unit Water of hydration often “driven off” by heating In formula, attached waters follow “· ” – CoCl2 ∙6H2O – cobalt (II) chloride hexahydrate Add suffix “_____hydrate” to name – CaSO4 ∙½H2O = calcium sulfate hemihydrate Hydrates Molecular Compounds First element Second named with prefix element + element name name with H2O prefix + element name + ide dihydrogen monoxide Prefixes indicate the number of each atom. 15 – Omit “mono” for first element Drop last “a” in prefix if element name begins with a vowel. Molecular Compounds Composed of two or more nonmetals Bonds are covalent Molecular Compounds Name the following molecular compounds. 1. BF3 – boron trifluoride 2. NO2 – nitrogen dioxide 3. PCl5 – phosphorus pentachloride 4. I2F7 – diiodine heptafluoride Acids Molecular compounds that form H+ when dissolved in water – To indicate the compound is dissolved in water, write (aq) after formula – Not named as the acid unless dissolved in water Have a sour taste Dissolve many metals – Ex: Mg, Fe, Zn Formula generally starts with “H” – Ex: HCl, H2SO4  Naming Acids and Bases Binary Acids positive negative charge when(1st) charge when (2nd) dissociated dissociated HCl(aq) hydro chloric acid (add acid to end of name) (use prefix (add –ic ending 19 hydro-) to anion) Oxyacids If the polyatomic ion name ends in “-ate”, change it to “-ic” If the polyatomic ion name ends in “-ite”, change it to “-ous” Add the word acid to the end of all acid names Example of Naming an oxyacid: H2SO4 1. Identify the anion: SO4 2- 2. Name the anion with the correct ending: sulfate  sulfuric 3. End with the word acid: sulfuric acid Naming Oxyacids Most acids contain more than two different elements. If one of the elements is oxygen then you have an oxyacid. It helps to think of these as hydrogen ions (H+) combined with an oxyanion. NO3− nitrate ion NO2− nitrite ion HNO3 nitric acid HNO2 nitrous acid if suffix is −ate change to −ic if suffix is −ite change to −ous 21 Note: Prefixes (like per- or hypo-) carry over.