2. Naming Chemical Compounds: A Review Ionic Compounds Covalent Compounds

3. Classifying Compounds The system for naming an ionic compound is different from that for naming a covalent compound, so before a compound can be named, it must be classified as ionic or covalent. Classifying a compound is not an easy task, but for the purposes of naming them, we employ a simple test: If the answer is yes, use the system for naming ionic compounds. If the answer is no, use the system for naming covalent compounds. Is there a metal or a polyatomic ion present?

4. Predicting Charges on Monatomic Ions KNOW THESE !!!! +1 +2 -3 -2 -1 0 Cd +2

5. Naming Ionic Compounds 1.Name the cation 2.Name the anion, drop the ending, add ide CaF 2 Mg 3 N 2 magnesium nitride K2OK2OK2OK2O potassium oxide calcium fluoride

6. Learning Check Complete the names of the following binary compounds: Na 3 Nsodium ________________ KBrpotassium________________ Al 2 O 3 aluminum ________________ MgS_________________________ nitride bromide oxide magnesiumsulfide

7. Name these Binary Ionic Compounds NaCl ZnI 2 Al 2 O 3 BeS LiBr K 3 P sodium chloride zinc iodide aluminum oxide beryllium sulfide lithium bromide potassium phosphide

8. Naming Ionic Compounds Transition Metals There are, however, two complicating factors: I. Some metals form more than one ion. II. Identifying polyatomic ions I. Metals that form more than one ion, such as iron, add a Roman numeral to the name to indicate the charge: Fe 2+ is called iron (II) and Fe 3+ is called iron (III) Assume a Roman numeral is required for any metal except 1. metals in groups IA and IIA on the periodic table 2. aluminum, cadmium, silver, and zinc

9. Naming Ionic Compounds (continued) If a Roman numeral is required, the charge on the metal ion must be determined from the charge on the negative ion.

10. Examples: CrO Since we know that O is a - 2 charge, Cr must be a +2 to balance it out. Chromium (II) oxide FeCl 3 Since we know that Cl is a - 1 charge, Fe must be a +3 to balance it out. Iron (III) chloride

11. Learning Check Complete the names of the following binary compounds with variable metal ions: FeBr 2 iron (_____) bromide CuClcopper (_____) chloride SnO 2 ___(_____ ) ______________ Fe 2 O 3 ________________________ Hg 2 S________________________ II I tinIVoxide iron (III) oxide mercury (I) sulfide

12. Now complete these… FeCl 2 iron (II) chloride Fe 2 O 3 iron (III) oxide PbS 2 lead (IV) sulfide Cu 3 Ncopper (I) nitride Cl has a 1- charge, and there are 2 of them for a total of 2-, so the Fe must be 2+ O has a 2- charge, and there are 3 of them for a total of 6-, so the Fe must have a total charge of 6+ split equally between the two iron atoms, so each must have a 3+ charge S has a 2- charge, and there are 2 of them for a total of 4-, so the Pb must be 4+ N has a 3- charge, so the Cu must have a total charge of 3+ split equally between the 3 copper atoms, so each must have a 1+ charge

13. Polyatomic ions PO 4 3- phosphate ion C 2 H 3 O 2 - acetate ion HC 2 H 3 O 2 Acetic Acid NO 3 -1 nitrate ion NO 2 -1 nitrite ion

14. Naming Ionic Compounds (continued) I. Polyatomic ions each have specific names which must be memorized so they can be recognized on sight. FormulaName C 2 H 3 O 2 1- acetate CO 3 2- carbonate HCO 3 1- bicarbonate NH 4 1+ ammonium A few of the more common polyatomic ions FormulaName NO 3 1- nitrate OH 1- hydroxide PO 4 3- phosphate SO 4 2- sulfate With Polyatomic Ions 1.Name the + ion or polyatomic ion 2.Name the – ion or polyatomic ion

15. IONIC COMPOUNDS NH 4 +1 Cl -1 ammonium chloride NH 4 Cl

16. Naming Ionic Compounds with Polyatomic Ions: n ame these… Na 2 SO 4 sodium sulfate Fe(NO 3 ) 2 iron (II) nitrate Al 2 (CO 3 ) 3 aluminum carbonate Pb(OH) 4 lead (IV) hydroxide (NH 4 ) 3 PO 4 ammonium phosphate MgNO 2 magnesium nitrite C 2 H 3 O 2 1- acetate CO 3 2- carbonate HCO 3 1- bicarbonate NH 4 1+ ammonium NO 3 1- nitrate OH 1- hydroxide PO 4 3- phosphate SO 4 2- sulfate * Groups I & II, Al, Zn, Cd, and Ag need no Roman numeral. AgC 2 H 3 O 2 silver acetate

17. Naming Molecular Compounds CH 4 methane BCl 3 boron trichloride CO 2 Carbon dioxide All are formed from two or more nonmetals. Ionic compounds generally involve a metal and nonmetal (NaCl)

18. Naming Molecular (Covalant) Compounds Covalent compounds are named by adding prefixes to the element names. The compounds named in this way are binary covalent compounds. ‘Binary’ means that only two atom are present. ‘Covalent’ (in this context) means both elements are nonmetals. The first element is given a prefix ONLY if there is more than one atom of the element. (Do not use mono) The second element is ALWAYS given a prefix, and ends in –ide.

19. Naming Covalent Compounds Prefixes SubscriptPrefix 1mono- 2di- 3tri- 4tetra- 5penta- SubscriptPrefix 6hexa- 7hepta- 8octa- 9nona- 10deca- Note: When a prefix ending in ‘o’ or ‘a’ is added to ‘oxide’, the final vowel in the prefix is dropped.

20. Learning Check Fill in the blanks to complete the following names of covalent compounds. CO carbon ______oxide CO 2 carbon _______________ PCl 3 phosphorus _______chloride CCl 4 carbon _____________ N 2 O_____nitrogen _____oxide 1mono 2di 3tri 4tetra 5penta 6hexa 7heptaa 8octa 9nona 10deca * Second element in ‘ide’ from * Drop –a & -o before ‘oxide’ mon dioxide tri tetrachloride di mon

21. Naming Binary Covalent Compounds try these… N 2 S 4 dinitrogen tetrasulfide NI 3 nitrogen triiodide XeF 6 xenon hexafluoride CCl 4 carbon tetrachloride P 2 O 5 diphosphorus pentoxide SO 3 sulfur trioxide 1mono 2di 3tri 4tetra 5penta 6hexa 7heptaa 8octa 9nona 10deca * Second element in ‘ide’ from * Drop –a & -o before ‘oxide’

22. Naming Compounds: Practice SiF 4 silicon tetrafluoride Na 2 CO 3 sodium carbonate N 2 O dinitrogen monoxide K 2 O potassium oxide Cu 3 PO 4 copper (I) phosphate CoI 3 cobalt (III) iodide AnalysisIf “Yes” * Is the cation a metal? (If so, does it need a Roman numeral? The compound is ionic: name each ion present (DO NOT USE PREFIXES) * Is there a polyatomic ion present? * Are both elements nonmetals? The compound is covalent: use prefixes (NO CHARGES EXIST) PI 3 phosphorus triiodide two nonmetals  covalent  use prefixes metal present  ionic  no prefixes Na  group I  no Roman numeral two nonmetals  covalent  use prefixes metal present  ionic  no prefixes K  group I  no Roman numeral metal present  ionic  no prefixes Cu  not group I, II, etc.  add Roman numeral (PO 4 is 3-, each Cu must be 1+) metal present  ionic  no prefixes Co  not group I, II, etc.  add Roman numeral (I is 1-, total is 3-, Co must be 3+) two nonmetals  covalent  use prefixes NH 4 Cl potassium oxide NH 4  polyatomic ion present  ionic  no prefixes

23. Writing Chemical Formulas: A Review Ionic Compounds Covalent Compounds

24. Classifying Compounds Classifying a compound using its name is not as difficult as using its formula. The names of covalent compounds will be easily recognized by the presence of the prefixes (mono-, di-, tri-, etc.). If no prefixes are present in the name, the compound is ionic. (Exception: some polyatomic ion names always contain prefixes (such as dichromate) but those will be memorized and recognized as ions.)

25. Writing Formulas for Ionic Compounds Formulas for ionic compounds are written by balancing the positive and negative charges on the ions present. Write the formula for the ionic compound that will form between Ba 2+ and Cl . Solution: 1. Balance charge with + and – ions 2. Write the positive ion of metal first, and the negative ion Ba 2+ Cl  Cl  3. Write the number of ions needed as subscripts BaCl 2

26. Learning Check Write the correct formula for the compounds containing the following ions: 1. Na +, S 2- a) NaS b) Na 2 Sc) NaS 2 2. Al 3+, Cl - a) AlCl 3 b) AlCl c) Al 3 Cl 3. Mg 2+, N 3- a) MgN b) Mg 2 N 3 c) Mg 3 N 2

27. Solution 1. Na +, S 2- b) Na 2 S 2. Al 3+, Cl - a) AlCl 3 3. Mg 2+, N 3- c) Mg 3 N 2

28. Writing Formulas for Ionic Compounds (continued) Helpful Rules to Remember NameReasoningFormula ammonium sulfate NH 4 has a 1+ charge & SO 4 has a 2- charge, so 2 ammonium ions are required for each sulfate. (NH 4 ) 2 SO 4 zinc chloride Zn has a 2+ charge & Cl has a 1- charge, so 2 chloride ions are required for each zinc ion. ZnCl 2 copper (II) phosphate Cu has a 2+ charge & PO 4 has a 3- charge, so 3 copper (II) ions are required for every two phosphate ions. Cu 3 (PO 4 ) 2 Examples A metal ion is always positive. The Roman numeral indicates the charge, not the subscript. The positive and negative charges must cancel (total charge must = 0). If more than one polyatomic ion is needed, put it in parentheses, and place a subscript outside the parentheses.

29. Learning Check 1. aluminum nitrate a) AlNO 3 b) Al(NO) 3 c) Al(NO 3 ) 3 2. copper(II) nitrate a) CuNO 3 b) Cu(NO 3 ) 2 c) Cu 2 (NO 3 ) 3. Iron (III) hydroxide a) FeOHb) Fe 3 OHc) Fe(OH) 3 4. Tin(IV) hydroxide a) Sn(OH) 4 b) Sn(OH) 2 c) Sn 4 (OH)

30. 1.Copper (II) chlorate 2.Calcium nitride 3.Aluminum carbonate 4.Potassium bromide 5.Barium fluoride 6.Cesium hydroxide Write the formula:

31. Writing Formulas for Covalent Compounds The names of covalent compounds contain prefixes that indicate the number of atoms of each element present. Remember:  The compounds named in this way are binary covalent compounds (they contain only two elements, both of which are nonmetals).  When in covalent compounds, atoms do not have charges. Subscripts are determined directly from the prefixes in the name. If no prefix is present on the name of the first element, there is only one atom of that element in the formula (its subscript will be 1). A prefix will always be present on the name of the second element. The second element will use the form of its name ending in ide.

32. Writing Formulas for Binary Covalent Compounds Try these… nitrogen dioxide NO 2 diphosphorus pentoxide P2O5P2O5 xenon tetrafluoride XeF 4 sulfur hexafluoride SF 6 1mono 2di 3tri 4tetra 5penta 6hexa 7heptaa 8octa 9nona 10deca * Second element in ‘ide’ from * Drop –a & -o before ‘oxide’

33. Writing Formulas: Practice carbon tetrafluorideCF 4 Na 3 PO 4 sodium phosphate Cu 2 SO 4 copper (I) sulfate AnalysisIf “Yes” The compound is covalent: the prefixes give the subscripts. * Are there prefixes present The compound is ionic: subscripts must be determined by balancing charges prefixes  covalent  prefixes indicate subscripts metal  ionic  balance charges  3 Na 1+ needed for 1 PO 4 3- metal present  ionic  balance charges  2 Cu 1+ needed for 1 SO 4 2- Al 2 S 3 aluminum sulfide metal present  ionic  balance charges  2 Al 3+ needed for 3 S 2- N 2 O 5 dinitrogen pentoxide prefixes  covalent  prefixes indicate subscripts NH 4 NO 3 ammonium nitrate polyatomic ion present  ionic  balance charges  1 NH 4 1+ needed for 1 NO 3 1- PbO 2 lead (IV) oxide metal present  ionic  balance charges  1 Pb 4+ needed for 2 O 2- Fe 2 (CO 3 ) 3 iron (III) carbonate metal present  ionic  balance charges  2 Fe 3+ needed for 3 CO 3 2-