Naming Chemical Compounds: A Review

1. Naming Chemical Compounds: A Review Ionic Compounds CovalentCompounds

2. 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: Is there a metal or a polyatomic ion present? If the answer is yes, use the system for naming ionic compounds. If the answer is no, use the system for naming covalent compounds.

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

4. Naming Ionic Compounds • Name the cation • Name the anion, drop the ending, add ide Mg3N2 magnesium nitride K2O potassium oxide CaF2 calcium fluoride

5. Learning Check Complete the names of the following binary compounds: Na3N sodium ________________ KBr potassium ________________ Al2O3 aluminum ________________ MgS _________________________ nitride bromide oxide magnesium sulfide

6. Name these Binary Ionic Compounds sodium chloride zinc iodide aluminum oxide beryllium sulfide lithium bromide potassium phosphide NaCl ZnI2 Al2O3 BeS LiBr K3P

7. 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: Fe2+ is called iron (II) and Fe3+is called iron (III) Assume a Roman numeral is required for any metalexcept 1. metals in groups IA and IIA on the periodic table 2. aluminum, cadmium, silver, and zinc

8. 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.

9. Examples: Since we know that O is a -2 charge, Cr must be a +2 to balance it out . CrO Chromium (II) oxide Since we know that Cl is a -1 charge, Fe must be a +3 to balance it out. FeCl3 Iron (III) chloride

10. Learning Check Complete the names of the following binary compounds with variable metal ions: FeBr2 iron (_____) bromide CuCl copper (_____) chloride SnO2 ___(_____ ) ______________ Fe2O3 ________________________ Hg2S ________________________ II I tin IV oxide iron (III) oxide mercury (I) sulfide

11. Now complete these… iron (II) chloride FeCl2 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 iron (III) oxide Fe2O3 PbS2 S has a 2- charge, and there are 2 of them for a total of 4-, so the Pb must be 4+ lead (IV) sulfide Cu3N copper (I) nitride 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

12. Polyatomic ions NO3-1 nitrate ion PO43- phosphate ion NO2-1 nitrite ion HC2H3O2 Acetic Acid C2H3O2- acetate ion

13. Naming Ionic Compounds (continued) I. Polyatomic ions each have specific names which must be memorized so they can be recognized on sight. • With Polyatomic Ions • Name the + ion or polyatomic ion • Name the – ion or polyatomic ion A few of the more common polyatomic ions

14. NH4+1 Cl-1 IONIC COMPOUNDS NH4Cl ammonium chloride

15. Naming Ionic Compounds with Polyatomic Ions:name these… Na2SO4 sodium sulfate Fe(NO3)2 iron (II) nitrate Al2(CO3)3 aluminum carbonate Pb(OH)4 lead (IV) hydroxide (NH4)3PO4 ammonium phosphate MgNO2 magnesium nitrite AgC2H3O2 silver acetate

16. Naming Molecular Compounds All are formed from two or more nonmetals. CO2 Carbon dioxide Ionic compounds generally involve a metal and nonmetal (NaCl) BCl3boron trichloride CH4 methane

17. 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.

18. Naming Covalent Compounds Prefixes Note: When a prefix ending in ‘o’ or ‘a’ is added to ‘oxide’, the final vowel in the prefix is dropped.

19. Learning Check Fill in the blanks to complete the following names of covalent compounds. CO carbon______oxide CO2carbon_______________ PCl3phosphorus_______chloride CCl4carbon _____________ N2O _____nitrogen _____oxide mon dioxide tri tetrachloride di mon

20. Naming Binary Covalent Compoundstry these… N2S4 dinitrogen tetrasulfide NI3 nitrogen triiodide XeF6 xenon hexafluoride CCl4 carbon tetrachloride P2O5 diphosphorus pentoxide SO3 sulfur trioxide

21. SiF4 silicon tetrafluoride two nonmetals  covalent  use prefixes Naming Compounds: Practice Na2CO3 sodium carbonate metal present  ionic  no prefixes Na  group I  no Roman numeral N2O dinitrogen monoxide two nonmetals  covalent  use prefixes K2O potassium oxide metal present  ionic  no prefixes K  group I  no Roman numeral Cu3PO4 copper (I) phosphate metal present  ionic  no prefixes Cu  not group I, II, etc.  add Roman numeral (PO4 is 3-, each Cu must be 1+) CoI3 cobalt (III) iodide metal present  ionic  no prefixes Co  not group I, II, etc.  add Roman numeral (I is 1-, total is 3-, Co must be 3+) PI3 phosphorus triiodide two nonmetals  covalent  use prefixes NH4Cl potassium oxide NH4 polyatomic ion present  ionic  no prefixes

22. Writing Chemical Formulas: A Review Ionic Compounds CovalentCompounds

23. 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.)

24. 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 Ba2+ and Cl. Solution: 1. Balance charge with + and – ions 2. Write the positive ion of metal first, and the negative ion Ba2+ Cl Cl 3. Write the number of ions needed as subscriptsBaCl2

25. Learning Check Write the correct formula for the compounds containing the following ions: 1. Na+, S2- a) NaS b) Na2S c) NaS2 2. Al3+, Cl- a) AlCl3 b) AlCl c) Al3Cl 3. Mg2+, N3- a) MgN b) Mg2N3 c) Mg3N2

26. Solution 1. Na+, S2- b) Na2S 2. Al3+, Cl- a) AlCl3 3. Mg2+, N3- c) Mg3N2

27. Writing Formulas for Ionic Compounds (continued) Helpful Rules to Remember 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. Examples

28. Learning Check 1. aluminum nitrate a) AlNO3 b) Al(NO)3 c) Al(NO3)3 2. copper(II) nitrate a) CuNO3 b) Cu(NO3)2 c) Cu2(NO3) 3. Iron (III) hydroxide a) FeOH b) Fe3OH c) Fe(OH)3 4. Tin(IV) hydroxide a) Sn(OH)4 b) Sn(OH)2 c) Sn4(OH)

29. Write the formula: • Copper (II) chlorate • Calcium nitride • Aluminum carbonate • Potassium bromide • Barium fluoride • Cesium hydroxide

30. Writing Formulas for Covalent Compounds The names of covalent compounds contain prefixes that indicate the number of atoms of each element present. 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. • 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.

31. Writing Formulas for Binary Covalent CompoundsTry these… nitrogen dioxide NO2 diphosphorus pentoxide P2O5 xenon tetrafluoride XeF4 sulfur hexafluoride SF6

32. carbon tetrafluoride CF4 Writing Formulas: Practice prefixes  covalent  prefixes indicate subscripts Na3PO4 sodium phosphate metal  ionic  balance charges  3 Na1+ needed for 1 PO43- copper (I) sulfate Cu2SO4 metal present  ionic  balance charges 2 Cu1+ needed for 1 SO42- aluminum sulfide Al2S3 metal present  ionic  balance charges 2 Al3+ needed for 3 S2- dinitrogen pentoxide N2O5 prefixes  covalent  prefixes indicate subscripts ammonium nitrate NH4NO3 polyatomic ion present  ionic  balance charges  1 NH41+ needed for 1 NO31- lead (IV) oxide PbO2 metal present  ionic  balance charges 1 Pb4+ needed for 2 O2- iron (III) carbonate Fe2(CO3)3 metal present  ionic  balance charges 2 Fe3+ needed for 3 CO32-