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How to Name Chemical Compounds In order to apply the proper nomenclature to chemical compounds, the compound itself needs to be identified as to type or class Question #1 What type of compound is it? Ionic? Molecular? - Organic? Acid? Hydrate? Identifying the Compounds Ionic – usually a compound composed of a metal & a nonmetal; a metal & a polyatomic anion; a polyatomic cation and a nonmetal; or a polyatomic cation & a polyatomic anion. Molecular – usually a compound composed of two nonmetals -organic compound (one containing carbon and frequently hydrogen; excludes CO, CO2, and carbonates) Identifying the Compounds Inorganic acids – these compounds contain hydrogen available for donation in a chemical reaction; their formulas generally start with H (hydrogen) and are followed by a nonmetal or polyatomic anion Hydrated compounds – these compounds appear as a salt or ionic compound with water molecules attached; meaning there is a dot (•), possibly a numerical coefficient, and the formula of water, H2 O Ionic Compound - Question #1 What is the positive ion? Metal from Group 1 (IA), Group 2 (IIA), Group 13 (IIIA) {first three elements} or Zn, Cd, or Ag? A metal not found in Group 1 (IA), Group 2 (IIA), Group 13 (IIIA) {first three elements} or Zn, Cd, Ag? A positive polyatomic ion? Naming Positive Ions For metals from Group 1 (IA), Group 2 (IIA), or Group 13 (IIIA) {first three elements} Zn, Cd, or Ag Write the name of the metallic element Naming Positive Ions For metals NOT found in Group 1 (IA), Group 2 (IIA), Group 13 (IIIA) {first three elements} or Zn, Cd, Ag Traditional name – apply an “-ic” suffix to the ion of greater charge and an “-ous” suffix to the ion of lesser charge. Stock System name – place a Roman numeral in parentheses, ( ), immediately after the element’s name. The Roman numeral indicates the charge on the metal ion in that compound. Identifying the Charge on the Cation In order to apply the Stock or traditional name, the charge on the metallic cation must be determined. How???? 1) Determine total negative charge in formula of the compound 2) Recognize, there is equal positive charge 3) Divide the positive charge by number of metal ions Naming Positive Ions For polyatomic cations Write the polyatomic ion’s name Ionic Compounds - Question #2 What is the negative ion? Nonmetal – elements located to the right of the staircase on the periodic table A negative polyatomic ion Naming Negative Ions For a nonmetallic anion – modify the name of the nonmetallic element with the attachment of an “-ide” suffix For a polyatomic anion - Write the name of the polyatomic ion. Molecular Compound – Question #1 Are you using the traditional or the Stock naming system? Traditional Naming of Molecular Compounds Attach a prefix to the name of each element that indicates the number of atoms of that element present in a molecule of the compound. In ADDITION, modify the more negative element’s name for the attachment of the “-ide” suffix Note: The more negative element has greater electronegativity or ionization energy A Reminder The “mono-” prefix is usually dropped from the more positive element Stock System Name of Molecular Compounds Represent the “apparent charge” of the more positive element with a Roman numeral in parentheses. Note: The more positive element has lower electronegativity or ionization energy. In ADDITION, modify the more negative element’s name for the attachment of the “-ide” suffix Molecular Naming Confusion….. When naming molecular compounds, name using the traditional system or the Stock system, but NOT a combination or hybrid of both systems!!!! Organic Compounds What type of organic compound is it? Alkane CnH2n+2 Alkene CnH2n Alkyne CnH2n-2 Alcohol R-OH (where R is any alkyl group) Prefixes are determined based upon number of carbon atoms MethEthPropButPentHexHeptOctNonDec- 1 2 3 4 5 6 7 8 9 10 Naming Alkanes In order to name an alkane, determine the number of carbon atoms in the chain and select the correct prefix. Attach the suffix “-ane” to the prefix. CH4 – methane C2H6 - ethane Naming Alkenes In order to name an alkene, determine the number of carbon atoms in the chain and select the correct prefix. Attach the suffix “-ene” to the prefix. If the double bond is not on a terminal carbon, use a number and dash to indicate its position in the molecule so the smallest number is used. Naming Alkenes C2H4 – ethene 3-heptene Naming Alkynes In order to name an alkyne, determine the number of carbon atoms in the chain and select the correct prefix. Attach the suffix “-yne” to the prefix. If the triple bond is not on a terminal carbon, use a number and dash to indicate its position in the molecule so the smallest number is used. Naming Alkynes C2H2 ethyne 2-hexyne Naming Alcohols In order to name an alcohol, determine the number of carbon atoms in the chain and select the correct prefix. Attach the suffix “-anol” to the prefix. If the –OH (hydroxyl group) is not on a terminal carbon, use a number and dash to indicate its position in the molecule so the smallest number is used. Naming Alcohols CH3OH methanol 2-butanol Acids – Question #1 Is the acid a binary acid/nonoxyacid; or is it an oxyacid? Oxyacid – contains hydrogen combined with an oxyanion Binary acid – contains hydrogen and a nonmetal Nonoxyacid – contains hydrogen and other polyatomic anion Binary or Non-oxyacids Acids The form for naming a binary or non-oxyacid is hydro – root of nonmetal/anion - ic Naming an Oxyacid The form for naming an oxyacid is Anion prefix - anion root - (-ic)/(-ous) If the polyatomic anion has a prefix (e.g. per- or hypo-) it is retained. What about - ic and – ous? If the oxyanion ends with an “-ate,” the “–ate” is replaced by the “-ic” suffix. If the oxyanion ends with an “-ite,” the “-ite” is replaced by the “–ous” suffix. Hydrated Compounds Question #1 What is the ionic compound or salt to which water is attached? Identify the ionic compound (salt) and name according to the rules discussed under ionic nomenclature Hydrated Compounds – Question #2 How many waters are attached to EACH formula unit of the ionic compound or salt? Look at the numerical coefficient of water Attach a prefix to the term “–hydrate” to indicate the number of waters present per formula unit. Prefixes to attach to hydrate Prefixes to attach to hydrate in indicating waters per formula unit. MonoDiTriTetraPentaHexaHeptaOctaNonaDeca-