2. Chemical Formulas and Chemical Compounds Heart cell rhythm depends on the opening and closing of a complex series of valves on the cell membrane, called ion channels. Some valves let certain ions ike potassium (K+) flow out, others let different ions like sodium (Na+) flow in. There are also pumps that actively move ions one direction or another.Notes 7

3. IonsIons Cation: A positive ionCation: A positive ion Mg 2+, NH 4 +Mg 2+, NH 4 + Anion: A negative ionAnion: A negative ion Cl , SO 4 2 Cl , SO 4 2  Ionic Bonding: Force of attraction between oppositely charged ions.Ionic Bonding: Force of attraction between oppositely charged ions.

4. Predicting Ionic Charges Group 1: Lose 1 electron to form 1+ ions H+H+H+H+ Li + Na + K+K+K+K+

5. Predicting Ionic Charges Group 2: Loses 2 electrons to form 2+ ions Be 2+ Mg 2+ Ca 2+ Sr 2+ Ba 2+

6. Predicting Ionic Charges Group 13: Loses 3 Loses 3 electrons to form 3+ ions B 3+ Al 3+ Ga 3+

7. Predicting Ionic Charges Group 14: Lose 4 Lose 4 electrons or gain 4 electrons? Neither! Group 14 elements rarely form ions.

8. Predicting Ionic Charges Group 15: Gains 3 Gains 3 electrons to form 3- ions N 3- P 3- As 3- Nitride Phosphide Arsenide

9. Predicting Ionic Charges Group 16: Gains 2 Gains 2 electrons to form 2- ions O 2- S 2- Se 2- Oxide Sulfide Selenide

10. Predicting Ionic Charges Group 17: Gains 1 Gains 1 electron to form 1- ions F 1- Cl 1- Br 1- Fluoride Chloride Bromide I 1- Iodide

11. Predicting Ionic Charges Group 18: Stable Noble gases do not form ions! Stable Noble gases do not form ions!

12. Predicting Ionic Charges Groups 3 - 12: Many transition elements Many transition elements have more than one possible oxidation state. have more than one possible oxidation state. Iron(II) = Fe 2+ Iron(III) = Fe 3+

13. Predicting Ionic Charges Groups 3 - 12: Some transition elements Some transition elements have only one possible oxidation state. have only one possible oxidation state. Zinc = Zn 2+ Silver = Ag +

14. Binary Ionic Compounds Binary ionic compounds means two ions,Binary ionic compounds means two ions, one that is positive in charge (cation)one that is positive in charge (cation) one that is negative in charge (anion)one that is negative in charge (anion) that react to form a compound.that react to form a compound.

15. Naming Ionic Binary Compounds 1.The ion with the positive charge (cation) is always written before the ion with the negative charge (anion) 2.The first word is the name of the element of which the cation originally came. (Example: Na + would be called Sodium) 3.The last word is the name of the element of which the anion originally came. (Example: Cl - would become chlorine, but the first part of the word is used and -ide is added to the end, so the last word would be Chloride.) 4.Put the two words together and that is the name of the compound. (Example: Na + and Cl - would become Sodium Chloride.)

16. Naming Ionic Compounds 1. Cation first, then anion1. Cation first, then anion 2. Monatomic cation = name of the element2. Monatomic cation = name of the element Ca 2+ = calcium ionCa 2+ = calcium ion 3. Monatomic anion = root + -ide3. Monatomic anion = root + -ide Cl  = chlorideCl  = chloride CaCl 2 = calcium chlorideCaCl 2 = calcium chloride

17. Naming Ionic Compounds (continued) - some metal forms more than one cation- some metal forms more than one cation -use Roman numeral in name-use Roman numeral in name PbCl 2PbCl 2 Pb 2+ is cationPb 2+ is cation PbCl 2 = lead(II) chloridePbCl 2 = lead(II) chloride Metals with multiple oxidation states

18. Polyatomic Ions Polyatomic Ions are ions that contain a number of ions.Polyatomic Ions are ions that contain a number of ions. There is no way to learn how to write their names, except to commit them to memoryThere is no way to learn how to write their names, except to commit them to memory

19. Common Polyatomic Ions (VIP) IonNameIonName NH 4 + AmmoniumO 2 -2 Peroxide NO 2 - NitriteCrO 4 -2 Chromate NO 3 - NitrateCr 2 O 7 -2 Dichromate SO 3 -2 SulfiteMnO 4 - Permanganate SO 4 -2 SulfateC2H3O2-C2H3O2- Acetate HSO 4 - Hydrogen SulfateClO 4 - Perchlorate OH - HydroxideClO 3 - Chlorate CN - CyanideClO 2 - Chlorite PO 4 -3 PhosphateClO - Hypochlorite HPO 4 - Hydrogen PhosphateHCO 3 - Hydrogen Carbonate H 2 PO 4 - Dihydrogen PhosphateCO 3 -2 Carbonate

20. Writing Ionic Compound Formulas Example: Ammonium sulfate 1. Write the formulas for the cation and anion, including CHARGES! NH 4 + SO 4 2- 2. Check to see if charges are balanced. 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! ( ) 2

21. Writing Ionic Compound Formulas Example: Iron(III) chloride 1. Write the formulas for the cation and anion, including CHARGES! Fe 3+ Cl - 2. Check to see if charges are balanced. 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! 3

22. Writing Ionic Compound Formulas Example: Aluminum sulfide 1. Write the formulas for the cation and anion, including CHARGES! Al 3+ S 2- 2. Check to see if charges are balanced. 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! 23

23. Writing Ionic Compound Formulas Example: Magnesium carbonate 1. Write the formulas for the cation and anion, including CHARGES! Mg 2+ CO 3 2- 2. Check to see if charges are balanced. They are balanced!

24. Writing Ionic Compound Formulas Example: Zinc hydroxide 1. Write the formulas for the cation and anion, including CHARGES! Zn 2+ OH - 2. Check to see if charges are balanced. 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! ( ) 2

25. Writing Ionic Compound Formulas Example: Barium nitrate 1. Write the formulas for the cation and anion, including CHARGES! Ba 2+ NO 3 - 2. Check to see if charges are balanced. 3. Balance charges, if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Not balanced! ( ) 2

26. Writing Ionic Compound Formulas Example: Aluminum phosphate 1. Write the formulas for the cation and anion, including CHARGES! Al 3+ PO 4 3- 2. Check to see if charges are balanced. They ARE balanced!

27. Binary Covalent Compounds Binary covalent compounds are those that do not involve metals or ions.Binary covalent compounds are those that do not involve metals or ions. An example of the difference between a covalent compound is that CO 2 is a covalent compound, but NaCl is not, because it contains Na +, a metal and an ion.)An example of the difference between a covalent compound is that CO 2 is a covalent compound, but NaCl is not, because it contains Na +, a metal and an ion.)

28. Naming Binary Compounds - Compounds between two nonmetals- Compounds between two nonmetals -First element in the formula is named first.-First element in the formula is named first. -Second element is named as if it were an anion.-Second element is named as if it were an anion. -Use prefixes-Use prefixes -Only use mono on second element --Only use mono on second element - P 2 O 5 = CO 2 = CO = N 2 O = diphosphorus pentoxide carbon dioxide carbon monoxide dinitrogen monoxide

29. Rules for naming a binary covalent compound 1.The first element in the formula uses the whole name of the element, much like binary ionic compounds. (Example: In NO, the first word would be Nitrogen.) 2.The second element in the formula only uses the first half of the word and -ide is added in place of the removed ending, much like binary ionic compounds. (Example: In NO, the first part of the second word would be - oxide.) 3.So the person reading the name can determine what the subscript is on each element, a prefix is added to show how many of each element are used. The first word of the formula does not use momo, so CO (Carbon Monoxide), NOT (Monocarbon Monoxide).

30. Prefixes in Chemical Names mono1 di2 tri3 tetra4 penta5 hexa6 hepta7 octa8 nona9 deca10

31. Calculating Formula Mass Calculate the formula mass of magnesium carbonate, MgCO 3. 24.31 g + 12.01 g + 3(16.00 g) = 84.32 g

32. Calculating Percentage Composition Calculate the percentage composition of magnesium carbonate, MgCO 3. From previous slide: 24.31 g + 12.01 g + 3(16.00 g) = 84.32 g 100.00

33. Formulas  molecular formula = (empirical formula) n [n = integer]  molecular formula = C 6 H 6 = (CH) 6  empirical formula = CH Empirical formula: the lowest whole number ratio of atoms in a compound. Molecular formula: the true number of atoms of each element in the formula of a compound.

34. Formulas (continued) Formulas for ionic compounds are ALWAYS empirical (lowest whole number ratio). Examples: NaClMgCl 2 Al 2 (SO 4 ) 3 K 2 CO 3

35. Formulas (continued) Formulas for molecular compounds MIGHT be empirical (lowest whole number ratio). Molecular: H2OH2O C 6 H 12 O 6 C 12 H 22 O 11 Empirical: H2OH2O CH 2 O C 12 H 22 O 11

36. Empirical Formula Determination 1.Base calculation on 100 grams of compound. 2.Determine moles of each element in 100 grams of compound. 3.Divide each value of moles by the smallest of the values. 4.Multiply each number by an integer to obtain all whole numbers.

37. Empirical Formula Determination Adipic acid contains 49.32% C, 43.84% O, and 6.85% H by mass. What is the empirical formula of adipic acid?

38. Empirical Formula Determination (part 2) Divide each value of moles by the smallest of the values. Carbon: Hydrogen: Oxygen:

39. Empirical Formula Determination (part 3) Multiply each number by an integer to obtain all whole numbers. Carbon: 1.50 Hydrogen: 2.50 Oxygen: 1.00 x 2 352 Empirical formula: C3H5O2C3H5O2

40. Finding the Molecular Formula The empirical formula for adipic acid is C 3 H 5 O 2. The molecular mass of adipic acid is 146 g/mol. What is the molecular formula of adipic acid? 1. Find the formula mass of C 3 H 5 O 2 3(12.01 g) + 5(1.01) + 2(16.00) = 73.08 g

41. Finding the Molecular Formula The empirical formula for adipic acid is C 3 H 5 O 2. The molecular mass of adipic acid is 146 g/mol. What is the molecular formula of adipic acid? 3(12.01 g) + 5(1.01) + 2(16.00) = 73.08 g 2. Divide the molecular mass by the mass given by the emipirical formula.

42. Finding the Molecular Formula The empirical formula for adipic acid is C 3 H 5 O 2. The molecular mass of adipic acid is 146 g/mol. What is the molecular formula of adipic acid? 3(12.01 g) + 5(1.01) + 2(16.00) = 73.08 g 3. Multiply the empirical formula by this number to get the molecular formula. (C 3 H 5 O 2 ) x 2 = C 6 H 10 O 4

43. The Mole 1 dozen = 1 gross = 1 ream = 1 mole = 12 144 500 6.02 x 10 23 There are exactly 12 grams of carbon-12 in one mole of carbon-12.

44. Avogadro’s Number 6.02 x 10 23 is called “Avogadro’s Number” in honor of the Italian chemist Amadeo Avogadro (1776-1855). Amadeo Avogadro I didn’t discover it. Its just named after me!

45. Calculations with Moles: Converting moles to grams How many grams of lithium are in 3.50 moles of lithium? 3.50 mol Li = g Li 1 mol Li 6.94 g Li 24.3

46. Calculations with Moles: Converting grams to moles How many moles of lithium are in 18.2 grams of lithium? 18.2 g Li = mol Li 6.94 g Li 1 mol Li 2.62

47. Calculations with Moles: Using Avogadro’s Number How many atoms of lithium are in 3.50 moles of lithium? 3.50 mol Li = atoms Li 1 mol Li 6.02 x 10 23 atoms Li 2.11 x 10 24

48. Calculations with Moles: Using Avogadro’s Number How many atoms of lithium are in 18.2 g of lithium? 18.2 g Li = atoms Li 1 mol Li6.02 x 10 23 atoms Li 1.58 x 10 24 6.94 g Li1 mol Li (18.2)(6.02 x 10 23 )/6.94