Naming and Understanding Chemical Formulas and Compounds

1. CCl4 MgCl2 • Guess at the names for these two compounds • Predict whether each is ionic or molecular compound • Understanding the difference in bonding, explain what the formula means for each. Draw pictures to help.

2. Ch. 7: Chemical Formulas and Compounds 7.1 Chemical Names and Formulas

3. Chemical Formulas • molecular compound • number of atoms of each element contained in a single molecule of the compound • NO2, CH2Cl2,

4. Chemical Formulas • ionic compound • represents one unit • simplest ratio of the compound’s anions and cations • MgO, Mg(OH)2, NH4Br

5. Monatomic Ions • ions formed from a single atom • Not all representative elements easily form ions • Some atoms form covalent bonds instead • Others form ions without noble gas configurations • d and p-block metals • many form 2+ or 3+, some +1 or +4

6. Monatomic Ions • type of ion can be determined by looking at the number of valence electrons in the neutral atom • atom is more stable with a full shell • zero valence • eight valence • determine which is easier for the atom to achieve

7. cation positive if the atom looses electrons B Mg Rb Al Na anion negative if the atom gains electrons N F S O Br Monatomic Ions

8. cations positive ion written first in formula by element’s name add a Roman Numeral if it can form more than 1 type of ion that is called the STOCK SYSTEM anions negative ion written second in formula by element’s root name + -ide ending Naming Monatomic Ions

9. Practice: Monatomic Ions • Identify the ion created by each atom and give the name for it: • Ga • Se • Ca • I • N • Li

10. Binary Ionic Compounds • compounds made of two different ions • Crossing Over • write two ion types with correct charges • make the anion’s charge, the cation’s subscript • make the cation’s charge, the anion’s subscript • simplify the ratio if possible • combine the names of the two ions

11. Al and O Mg and Br Cu and Br Practice Naming

12. iron (III) sulfide cadmium oxide potassium nitride tin (IV) sulfide Practice Writing Formulas

13. Cmpds with Polyatomic Ions • the cation or anion could be a group of covalently bonded atoms instead of one atom • most polyatomic ions are oxyanions: • polyatomic ions containing oxygen • more than one polyatomic anion can exist for one element • sulfate ion: SO42- sulfite ion: SO32-

14. KNO3 Cu(OH)2 NH4Br CaSO4 Practice Naming

15. sodium permanganate iron (II) chlorite ammonium acetate calcium carbonate Practice Writing Formulas

16. Write the formula for • barium nitrate • zinc phosphate

17. Traditional vs. Stock • Stock System • using Roman Numerals in names of metal ions with more than one charge • more important and used more often • Traditional • add –ic or –ous ending to metal name • lower charge: -ous, higher charge: -ic • Shown on the chart below Stock System chart

18. stannous chloride SnCl2 chromic sulfate Cr2(SO4)3 plumbic nitrate Pb(NO3)4 aurous oxide Au2O ferric phosphate FePO4 cuprous chlorate CuClO3 Examples

19. CuCl2 cupric chloride Pt3(PO4)2 plantinous phosphate AuBr aurous bromide PbO plumbous oxide SnO2 stannic oxide Fe(NO3)2 ferric nitrate Examples

20. Acids Acids will be focused on greatly later on in the year Can be identified by H being first in the formula All acids contain hydrogen and an anion Can be polyatomic anion : HNO3 Can be monatomic anion: HBr Name is based on the anion root

21. Binary Acids Only H and monatomic anion Naming Hydro- prefix Root of element name -ic ending Example: HBr, hydrobromic acid H2S, hydrosulfic acid

22. Ternary Acids Naming Polyatomic ion name If it has –ate ending, change to –ic If it has –ite ending, change to –ous Examples: HNO3: from nitrate, so nitric acid H2SO3: from sulfite, so sulfurous acid

23. Practice HBr Binary HClO3 Ternary H2C2O4 ternary H3AsO3 Ternary H2Se Binary H2S binary

24. Writing Formulas for Acids Determine if it is binary (has hydro-prefix) or ternary (no hydro- prefix) Find the anion contained in the acid (binary- element, ternary- polyatomic ion) add enough H+1 ions to balance the charge of the anion to the front

25. Practice sulfuric acid nitrous acid hydrofluoric acid hydrosulfuric acid phosphoric acid formic acid

26. Write the formula for sodium sulfate and determine the number of atoms in one unit.

27. Ch. 7: Chemical Formulas and Names Oxidation States 7.2

28. Oxidation States Also called oxidation numbers For an individual atom of one type Used to indicate approximate electron distribution in covalent bonding What contains covalent bonding? molecular compounds polyatomic ions Not “real” charges since electrons are shared

29. Oxidation States Shared electron are counted as “belonging” to the more electronegative element Since it has a greater attraction for the electrons The electrons are actually located closer to that atom Periodic Trend for electronegativity: increases as you go up and go to the right

30. Assigning Oxidation States Atoms in a pure element have an oxidation state of zero. Na, O2, Fe, etc. The more electronegative element is assigned a negative oxidation state while the less electronegative has a positive state CF4: C is less electronegative: + F is more electronegative: -

31. Assigning Oxidation States Fluorine always has a -1 oxidation state Since it is the most electronegative element Oxygen usually has a -2 Except in peroxides where it has a -1 Hydrogen usually has a +1 But when it is paired with a metal, it has a -1: ex. LiH

32. Assigning Oxidation States Sum of the oxidation states must equal zero in a neutral compound N2O5 O: -2 x 5 = -10 N: +5 x 2 = +10 Sum of states in a monatomic/polyatomic ion must equal the charge of the ion NO3-1 O: -2 x 3 = -6 N: + 5 x 1 = +5

33. Practice UF6 H2SO4 ClO31- CO2

34. Determine the Oxidation States Br2 NH3 CaSO3 HSO3- B2H6

35. Using Oxidation States in Naming Can use Stock System (Roman Numerals) to names molecular compounds too The Roman Numeral in between names is the oxidation state of the first element Do NOT simplify the ratio for molecular compounds Only use either prefixes OR Roman Numerals, not a combination

36. Stock System Naming PCl3 Cl: -1, P: +3 Phosphorus (III) chloride PCl5 Cl: -1, P: +5 Phosphorus (V) chloride N2O O: -2, N: +1 Nitrogen (I) oxide

37. Stock System Naming CO BrF5 CO2

38. Writing Formulas Nitrogen (II) oxide N: 2+ O: -2 NO Lead (IV) oxide Pb: +4 O: -2 Pb2O4 PbO2 Sulfur (IV) fluoride S: +4 F: -1 SF4 Chlorine (III) fluoride Cl: +3 F: -1 ClF3

39. Writing Formulas Phosphorus (V) oxide Boron (III) hydride Hydrogen (I) oxide carbon (IV) sulfide

40. Name the following compounds Na2CO3 H2SO4 N2O4

41. Ch. 7: Chemical Formulas and Compounds 7.3 Uses of Chemical Formulas

42. Meaning of Formulas the subscripts in a formula give you: simplest ratio of atoms OR the number of atoms in a molecule What type of compound has a formula that is always the simplest ratio? What type of compound forms a molecule? ALWAYS provides you with a ratio of moles of atoms Example: C13H18O2 13 moles of C : 18 moles of H : 2 moles of O

43. Example If I have 2.00 moles of C13H18O2, how many moles of each atom would I have?

44. Formula Mass mass of a molecule, ion, or formula unit sum of mass of all atoms in the chemical formula in amu Ex: H2O 18.01528 amu formula mass = molecular mass for molecular compound

45. Example Find formula mass of potassium chlorate. KClO3

46. Molar Masses mass of one mole of pure substance numerically equal to formula mass units: g/mol Find molar mass of barium nitrate. Ba(NO3)2

47. Molar Mass in Conversions can be used as a conversion factor between grams and moles What is the mass in grams of 2.50 mol of oxygen gas?

48. Example Ibuprofen, C13H18O2, is the active ingredient in many pain relievers. Find molar mass:

49. Example If the tablets in a bottle contain a total of 33 g of ibuprofen, how many moles are in one bottle? How many molecules of ibuprofen are in the bottle?

50. Example What is the number of moles of carbon in that bottle? What is the total mass in grams of carbon in the bottle?