2. Naming Compounds What's in a name? That which we call a rose By any other name would smell as sweet." - William Shakespeare, Romeo and Juliet (II, ii)

3. Prior to the 1700s, there was no systematic method of naming compounds. Substances were named in variety of ways, such as the use of compounds, the property of the compound, or the source of the substance. These names give little, if any, information about the composition of the compound.

4. Common Name: Quick lime/ Lime IUPAC Name: Calcium Oxide Chemical Formula: CaO Use or property: Neutralizing acidified lakes

5. Common Name: Baking Soda IUPAC Name: Sodium bicarbonate Chemical Formula: NaHCO 3 Use or property: Making baked goods rise

6. Common Name: Laughing gas IUPAC Name: Dinitrogen monoxide Chemical Formula: N 2 O Use or property: Used in dentistry as anaesthetic

7. Common Name: Table salt IUPAC Name: Sodium Chloride Chemical Formula: NaCl Use or property: Enhancing flavour

8. Common Name: Quartz sand IUPAC Name: Silicon dioxide Chemical Formula: SiO 2 Use or property: manufacturing glass

9. Valence electrons are the number of electrons in the outer energy level of an atom. “ Valence ” describes the number of electrons gained, lost or shared to achieve stability. For first 20 elements valence starts at 1 (alkali metals), climbs to 4 (group 4) and falls back to 1 (halogens) By knowing the valence of elements you can determine the formula of compounds E.g. what compound would form from C + S? Step 1 - write valences: Step 2 – balance valences by adding atoms: Step 3 – write # of each atom as a subscript Background: valences and formulas C S 4 2 C S 4 2 2 CS 2

10. a) Al,Br b) K,S c) Zn,O d) Mg,N e) C,Cl f) Na,O AlBr 3 K2SK2SZnOMg 3 N 2 CCl 4 Na 2 O Al Br 3 1 1 AlBr 3 K S 1 2 1 K 2 S Zn O 2 ZnO Mg N 2 3 2 Mg 3 N 2 C Cl 4 1 1 CCl 4 Na O 1 2 1 Na 2 O

11. Ionic compounds Rules for naming Names end in -ide. Example: sodium chloride 1. Write metal name first then non metal 2. Change the ending of the non metal to “ ide ” 3. Do not capitalized unless starting a sentence Give formulae & name: Ca + I, O + Mg, Na + S = Ca 2 I 1 = CaI 2 = calcium iodide = Mg 2 O 2 = MgO = magnesium oxide = Na 1 S 2 = Na 2 S = sodium sulfide

12. Multiple Valence Some metals have more than one valence. For these metals, you can use the Latin or IUPAC method Latin is older (not useful for some compounds) IUPAC is more commonly used

13. Latin naming As before, the metal name if written first and the non metal ends in -ide The metal is named with it ’ s Latin or English root and ends in “– ic ” or “– ous ” to denote valence E.g. Cu 1 is cuprous, E.g. Cu 2 is cupric Lower = ous, Higher = ic Give formulas and Latin names for: Cu 2 + Cl = Cu 2 Cl 1 = CuCl 2 = cupric chloride Cu 1 + Cl = Cu 1 Cl 1 = CuCl = cuprous chloride

14. High with the “i” Low with the “o”

15. Name the following: FeCl 2 –Fe -> +2 –Cl -> -1 CuO –Cu -> +2 –O -> -2 –Ferrous chloride - Cupric oxide

16. Metal comes first, ending of non metal is “ ide ” The valence of the metal is indicated in brackets using roman numerals E.g. Cu 1 is copper(I), Cu 2 is copper(II) Numbers refer to valences not to #s of atoms Try: Cu 2 +Cl, Zn 2 + Cl, Co 2 +Cl, Hg+S (do both) Cu 2 +Cl = Cu 2 Cl 1 = CuCl 2 = copper(II) chloride Zn 2 +Cl = Zn 2 Cl 1 = ZnCl 2 = zinc chloride Co 2 +Cl = Co 2 Cl 1 = CoCl 2 = cobalt(II) chloride Hg+S = Hg 1 S 2 = Hg 2 S = mercury(I) sulfide Hg+S = Hg 2 S 2 = HgS = mercury(II) sulfide IUPAC naming

17. Groups of atoms can also have valences “ Polyatomic ions ” are groups of atoms that interact as a single unit. E. g. OH 1, (SO 4 ) 2. Ba 3 (PO 4 ) 2 = Compounds containing polyatomic ions So far we have given valences to single atoms Li + O Li 1 O 2  Li 2 O barium phosphate Naming compounds with polyatomic ions is similar to naming other ionic compounds Put the metal name first, then the name of the polyatomic second. You should note that compounds with polyatomic ions have names ending in -ate or -ite not -ide Name: Ca(OH) 2, CuSO 4, NH 4 NO 3, Co 2 (CO 3 ) 3

18. - calcium hydroxide - copper(II) sulfate - ammonium nitrate - cobalt(III) carbonate Ca(OH) 2 CuSO 4 NH 4 NO 3 Co 2 (CO 3 ) 3 Compounds containing polyatomic ions

19. Naming covalent compounds -ide ending, each element has “ prefix ” 1mono 2di 3tri 4tetra 5penta 6hexa 7hepta 8octa 9nona 10deca prefix refers to # of atoms - not valence N 2 O 4 = dinitrogen tetroxide Exception: drop mono for first element CO 2 = carbon dioxide The first vowel is often dropped to avoid the combination of “ao” or “oo”. CO = carbon monoxide (monooxide) SO 2 = sulfur dioxide (doxide) Name: CCl 4, P 2 O 3, IF 7 P 4 O 10 = tetraphosphorus decoxide

20. Write and name the following covalent compounds (IUPAC) carbon tetrachloride diphosporus trioxide iodine heptafluoride CCl 4 P 2 O 3 IF 7

21. Write the formulas for the following covalent compounds (IUPAC) dicarbon tetrasulfide pentaphosphous dioxide iodine octafluoride C 2 Cl 4 P 5 O 2 IF 8