2-1 C & D: Names and Formulas of Compounds

1. 2-1 C & D: Names and Formulas of Compounds

2. Ionic Compound Formation • Ionic compounds are made up of positive and negative ions. • All of the positive and negative ions organize in a pattern. • Negative-positive attract. • Negative-negative and positive-positive repel. • Ionic compounds form from the inside out as solid crystals. • Ionic compounds are like a solid stack of bricks. • A salt shaker contains thousands of small pieces of NaCl.

3. Covalent Compound Formation • Covalent molecules share electrons. • There is generally no order to the formation of covalent molecules. • These molecules clump together as solids, liquids or gases. • Covalent molecules are like a play-pit full of plastic balls. • Each plastic ball = 1 covalent molecule of H2O

4. Names & Formulas of Ionic Compounds Remember: Ionic compounds are composed of ions (1 positive and 1 negative) To Name an Ionic Compound: • Name the cation: - it’s the same as on the periodic table • Name the anion -drop the end of the element name and add “ide”

5. Examples: • NaCl • KBr • CaF2 4. MgO

6. Ionic Compound Formulas • Symbols represent the elements in the compound • Subscript numbers following the symbol show how many of each element are present. Example: Sr3P2 - Contains 3 atoms Sr (strontium) and 2 atoms P (phosphorus)

7. Writing Ionic Compound Formulas • The ion charge shows what ion each element forms to complete their valence shell of electrons • Al has an ion charge of +3, therefore it loses 3 electrons • Br has an ion charge of -1, therefore it gains one electron • For Al and Br to form a compound Al needs to give away 3 electrons and Br needs to accept them. • But wait!!! Br only needs to accept one, so how does this work??

8. Writing Ionic Compound Formulas • Each Br can accept only 1 electron, so 3 Br atoms are needed to combine with 1 Al • The overall formula needs to show this  AlBr3

9. Writing Ionic Compound Formulas • What would the Ionic Formula be for a compound made of Aluminum and Sulphur? • Al has an ion charge of +3 • S has an ion charge of -2

10. For all elements to end up with full valence shells, 2 atoms of Al and 3 of S are required. • Formula = Al2S3

11. Shortcut to write the formula: • Write the symbol and ion charge of the cation • Write the symbol and ion charge of the anion • “Swap and drop” the charges and write as subscripts • Reduce numbers (if possible)

12. Examples: Aluminum sulphide Al+3 S-2 Al S Al2S3

13. Examples: Magnesium Oxide Mg+2 O-2 Mg O Mg2O2 REDUCE!! MgO

14. Practice: • Write formulas for the following ionic compounds: Zn+2 with I-1

15. Practice: • Write formulas for the following ionic compounds: Al+3 with P-3

16. Practice: • Write formulas for the following ionic compounds: Ca+2 with O-2

17. Practice: • Write formulas for the following ionic compounds: Barium phosphide

18. Practice: • Write formulas for the following ionic compounds: Lithium fluoride

19. Practice: • Write formulas for the following ionic compounds: Aluminum nitride

20. Assignment: • Complete the practice problems on pages 187 and 188 • Complete Nomenclature Packet Worksheet 1

21. Compounds Containing a Multivalent Metal • Multivalent metals have more than one possible ion charge. • The name must indicate which ion charge is used in the formation of the compound • We use roman numerals to indicate ion charge: I = 1 VI = 6 II = 2 VII = 7 III = 3 VIII = 8 IV = 4 IX = 9 V = 5 X = 10

22. Compounds Containing a Multivalent Metal Examples: V4+ = Vanadium (IV) Ni3+ = Nickel (III) • Writing formulas is identical to other ionic compounds, simply use the roman numeral to determine the ion charge of the cation!

23. Compounds Containing a Multivalent Metal Example: • Copper (I) nitride

24. Compounds Containing a Multivalent Metal Example: • Manganese (IV) oxide

25. Compounds Containing a Multivalent Metal Example: • Chromium (III) bromide

26. Compounds Containing a Multivalent Metal • Naming these types of compounds requires an extra step • I will show you two different methods, the first requires that you must UNCRISSCROSS!!

27. Compounds Containing a Multivalent Metal Example: Name PdS2 1. Look up the metal on the periodic table and confirm that it is multivalent. 2. Uncrisscross so that the subscripts become charges once again Pd1S2 Pd2+ S1-

28. Compounds Containing a Multivalent Metal • Check the ion charge of the non-metal to make sure it’s correct. If not, multiply both charges to make it correct. Pd2+ S1- - wait!! Sulfur should have an ion charge of -2!! -to fix this, multiply both ion charges by 2 Pd4+ S2-

29. Compounds Containing a Multivalent Metal • Name the metal, using roman numerals to indicate its ion charge Palladium (IV) • Name the non-metal, swapping ending for –ide. Palladium (IV) Sulphide

30. Compounds Containing a Multivalent Metal The second method uses a “teeter-totter” to figure out the charge of the multivalent metal Example: Name PdS2

31. Compounds Containing a Multivalent Metal Practice! Name this compound: SnBr2

32. Compounds Containing a Multivalent Metal Practice! Name this compound: VCl5

33. Compounds Containing a Multivalent Metal Practice! Name this compound: Ni2S3

34. A site for extra practice http://www.pafaculty.net/biology/keith/KR_Graph_site/ionic_nomenclature_page.htm

35. Assignment: • Complete the practice problems on pages 190 and 191 • Complete Nomenclature Packet Worksheet 2

36. Polyatomic Ions • Some special molecules lose or gain electrons as a group • These ionic molecules are called polyatomic ions

37. Polyatomic Ions • You can recognize that a compound has a polyatomic ion in it because it will be made up of MORE THAN 2 TYPES OF ATOMS! • The name is still made up of ONLY 2 PARTS! Naming: Example: NaNO3 • Name the cation Sodium 2. Name the polyatomic ion Nitrate Sodium Nitrate

38. Practice: • Name the following compound K2Cr2O7

39. Practice: • Name the following compound Fe(OH)3

40. Writing Formulas • Write the symbol and ion charge for both parts of the name • Criss Cross the charges - put brackets around the polyatomic ion if necessary 3. Reduce if possible Example: Calcium Bicarbonate Ca2+ HCO3- Ca HCO3 Ca(HCO3)2

41. Practice: • Write the formula for the following compound Ammonium chloride

42. Practice: • Write the formula for the following compound Manganese (III) chlorate

43. Complete the Practice Problems on Page 193 • Complete Nomenclature Packet Worksheet #3 • Complete Nomenclature Packet Worksheet #4 – Be careful, this one mixes up all the different types of ionic compounds!

44. Binary Covalent Molecules • These are molecules made up of 2 types of non-metals. • The systems for naming and writing formulas for these compounds is very different than the ionic compounds we’ve looked at so far

45. Binary Covalent Molecules • The names of these compounds tell you exactly how many of each atom are present. • There is no need to look up charges or crisscross!! The Prefixes:

46. Binary Covalent Molecules Naming Molecules: • Name the left element • Add a prefix in front of the element symbol indicating how many atoms of that element are present (unless there is only one, then don’t use a prefix) • Name the second element • Add a prefix in front of the element symbol indicating how many atoms of the 2nd element are present (use mono as the prefix if there is only one)

47. Examples: CO N2O3

48. Binary Covalent Molecules Writing Formulas: • Look at prefix and name of first element. Write the element symbol followed by a subscript number showing how many of that element are present. • Look at prefix and name of second element. Write the element symbol followed by a subscript number showing how many of that element are present. • DO NOT REDUCE!!!!!!!

49. Binary Covalent Molecules Examples: Nitrogen tribromide

50. Binary Covalent Molecules Examples: Disulfur decafluoride