1. Chapter 7 Part 2 Chemical Nomenclature CHM 1010 PGCC Barbara Gage “Chemical Nomenclature as we know it is born with the publication of Méthode de nomenclature chimique by Antoine-Laurent Lavoisier, Claude-Louis Berthellot, Antoine de Fourcroy, and Guyton de Morveau. The names proposed were based on the elements origin or function. (Image produced courtesy of the Library & Information Centre, Royal Society of Chemistry)” http://www.rsc.org/chemsoc/timeline//pages/1787.html

2.  System of rules for naming pure substances  Elements – element name used even if the substance is di- or polyatomic O 2 = oxygen S 8 = sulfur  Compounds - naming differs depending on whether a substance is held together primarily by ionic or covalent bonds. CHM 1010 PGCC Barbara Gage Chemical Nomenclature

3. CHM 1010 PGCC Barbara Gage -- 1+ 2+3+1-2-3- Generally metals form cations and non-metals form anions.

5.  Cations (positively charged ions) and anions (negatively charged ions) will associate with each other and form a neutral binary compound to reduce energy.  1 Na + 1 Cl - NaCl  1 Ca 2+ 1 O 2- CaO  3 K + 1 N 3- K 3 N  2 Al 3+ 3 S 2- Al 2 S 3 CHM 1010 PGCC Barbara Gage Binary Ionic Compounds

6. Naming binary ionic compounds The name of the cation is the same as the name of the metal. Many metal names end in -ium. The name of the anion (negatively charged ion) takes the root of the nonmetal name and adds the suffix -ide. Calcium and oxygen form calcium oxide. Aluminum and sulfur form aluminum sulfide. The name of the cation (positively charged ion) is written first, followed by that of the anion. CHM 1010 PGCC Barbara Gage

7. Naming Ionic Binary Compounds

8. Naming Binary Ionic Compounds PROBLEM: Name the ionic compound formed from the following pairs of elements: PLAN: (a) magnesium and nitrogen SOLUTION: Use the periodic table to decide which element is the metal and which the nonmetal. The metal (cation) is named first and we use the -ide suffix on the nonmetal name root. (b) iodine and cadmium (c) strontium and fluorine(d) sulfur and potassium (a) magnesium nitride (b) cadmium iodide (c) strontium fluoride (d) potassium sulfide From Silberberg, Principles of Chemistry CHM 1010 PGCC Barbara Gage

9. Determining Formulas of Binary Ionic Compounds PROBLEM: Write simplest formulas for the compounds named in Sample Problem 2.5. PLAN: SOLUTION: Compounds are neutral. We find the smallest number of each ion which will produce a neutral formula. Place subscripts to the right of the element symbol. (a) Mg 2+ and N 3- ; three Mg 2+ (6+) and two N 3- (6-); Mg 3 N 2 (b) Cd 2+ and I - ; one Cd 2+ (2+) and two I - (2-); CdI 2 (c) Sr 2+ and F - ; one Sr 2+ (2+) and two F - (2-); SrF 2 (d) K + and S 2 - ; two K + (2+) and one S 2 - (2-); K 2 S CHM 1010 PGCC Barbara Gage

10.  The “B” group elements may form cations with more than one charge.  To specify which cation forms a compound, a roman numeral equal to the charge is added to the cation name. Fe 2+ = iron (II) Fe 3+ = iron (III) CHM 1010 PGCC Barbara Gage Binary Ionic Compounds

11. CHM 1010 PGCC Barbara Gage

12. Sample Problem 2.7Determining Names and Formulas of Ionic Compounds of Elements That Form More Than One Ion PLAN: SOLUTION: Compounds are neutral. We find the smallest number of each ion which will produce a neutral formula. Use subscripts to the right of the element symbol. PROBLEM: Give the systematic names for the formulas or the formulas for the names of the following compounds: (a) tin(II) fluoride(b) Cr I 3 (c) manganese (IV) sulfide (d) CrO 3 (a) Tin (II) is Sn 2+ ; fluoride is F - ; so the formula is SnF 2. (b) The anion I is iodide( I - ); 3I - means that Cr(chromium) is +3. Cr I 3 is chromium(III) iodide (c) Manganese (IV) is Mn 2+ ; oxide is S 2-, therefore the formula is MnS 2. (d) Cr is chromium; the anion O is oxide(2-); the compound is cobalt (VI) oxide. Modified from Silberberg, Principles of Chemistry

13.  Some atoms form bonds that hold atoms together in a structure that has an overall charge (rather than as a neutral compound. These ions are called polyatomic ions.  CO 3 2- carbonate SO 4 2- sulfate  Compounds with polyatomic ions are named with the cation and anion name.  Na 2 SO 4 – sodium sulfate CHM 1010 PGCC Barbara Gage Polyatomic Ions

14. CHM 1010 PGCC Barbara Gage

15. Determining Names and Formulas of Ionic Compounds Containing Polyatomic Ions PLAN: SOLUTION: Note that polyatomic ions have an overall charge so when writing a formula with more than one polyatomic unit, place the ion in a set of parentheses. PROBLEM: Give the systematic names or the formula or the formulas for the names of the following compounds: (a) Fe(ClO 4 ) 2 (b) sodium sulfite (a) ClO 4 - is perchlorate; iron must have a 2+ charge. This is iron(II) perchlorate. (b) The anion sulfite is SO 3 2- therefore you need 2 sodiums per sulfite. The formula is Na 2 SO 3.

16.  Some compounds have water molecules attached as part of their structure. These are termed hydrates.  CuSO 4. 5H 2 O copper (II) sulfate pentahydrate CHM 1010 PGCC Barbara Gage Hydrates Numerical Prefixes for Hydrates and Binary Covalent Compounds Number Prefix Number Prefix Number Prefix 1mono 2di 3tri 4tetra 5penta 6hexa 8octa 9nona 10deca

17.  When certain binary gases dissolve in water they form acids with the same formula. The name is changed to add –ic acid to the anion HCl (g)  HCl (aq) hydrogen chloride hydrochloric acid CHM 1010 PGCC Barbara Gage Binary Acids

18.  HF (aq)hydrofluoric acid  HCl (aq)hydrochloric acid  HBr (aq)hydrobromic acid  HI (aq)hydroiodic acid  HCN (aq)hydrocyanic acid CHM 1010 PGCC Barbara Gage Binary Acids

19.  Acids containing oxygen; most do not exist in the same form without water HNO 3 nitric acid HNO 2 nitrous acid H 2 SO 4 sulfuric acid H 2 CO 3 carbonic acid H 3 PO 4 phosphoric acid HC 2 H 3 O 2 or CH 3 COOH acetic acid CHM 1010 PGCC Barbara Gage Oxyacids

20.  Non-metals form bonds by sharing electrons rather than transferring them.  The resulting bond is referred to as a covalent bond.  The element farthest to the left or lower on the periodic table is generally written first. Subscripts are replaced by numerical prefixes in the name. CHM 1010 PGCC Barbara Gage Covalent Binary Compounds

21.  CO 2 carbon dioxide  N 2 Odinitrogen oxide  P 2 S 5 diphosphorus pentasulfide  SiCl 4 silicon tetrachloride  For compounds where two vowels occur together when the prefix is added, the vowel from the prefix can be dropped (except for iodine).  N 2 O 5 dinitrogen pentaoxide CHM 1010 PGCC Barbara Gage Covalent Binary Compounds

22. CHM 1010 PGCC Barbara Gage Naming Binary Covalent Compounds

23. CHM 1010 PGCC Barbara Gage Determining Names and Formulas of Binary Covalent Compounds SOLUTION: PROBLEM:(a) What is the formula of carbon disulfide? (b) What is the name of PCl 5 ? (a) Carbon is C, sulfide is sulfur S and di-means 2 - CS 2. (b) P is phosphorus, Cl is chloride, the prefix for 5 is penta-. Phosphorus pentachloride.

24. CHM 1010 PGCC Barbara Gage