Chapter 9

1. Chapter 9 Naming Compounds Writing Formulas

2. Systematic Naming • There are too many compounds to remember the names of them all. • Compound is made of two or more elements. • Put together atoms. • Name should tell us how many and what type of atoms.

3. Periodic Table • More than a list of elements. • Put in columns because of similar properties. • Each column is called a group.

4. Representative elements 1A 0 5A 7A 2A 3A 4A • The group A elements • The tall columns 6A

5. Metals

6. Transition metals • The Group B elements

7. Non-metals • Dull • Brittle • Nonconductors- insulators

8. Metalloids or Semimetals • Properties of both • Semiconductors

9. Atoms and ions • Atoms are electrically neutral. • Same number of protons and electrons. • Ions are atoms, or groups of atoms, with a charge. • Different numbers of protons and electrons. • Only electrons can move. • Gain or lose electrons.

10. Anion • Anegative ion. • Has gained electrons. • Non metals can gain electrons. • Charge is written as a superscript on the right. F1- Has gained one electron O2- Has gained two electrons

11. Cations • Positive ions. • Formed by losing electrons. • More protons than electrons. • Metals form cations. K1+ Has lost one electron Ca2+ Has lost two electrons

12. Two Types of Compounds • Molecular compounds • Made of molecules. • Made by joining nonmetal atoms together into molecules.

13. Two Types of Compounds • Ionic Compounds • Made of cations and anions. • Metals and nonmetals. • The electrons lost by the cation are gained by the anion. • The cation and anions surround each other. • Smallest piece is a FORMULA UNIT.

14. Two Types of Compounds Ionic Molecular Smallest piece Formula Unit Molecule Types of elements Metal and Nonmetal Nonmetals Solid, liquid or gas State solid Melting Point High >300ºC Low <300ºC

15. Chemical Formulas • Shows the kind and number of atoms in the smallest piece of a substance. • Molecular formula- number and kinds of atoms in a molecule. • CO2 • C6H12O6

16. Formula Unit • The smallest whole number ratio of atoms in an ionic compound. • Ions surround each other so you can’t say which is hooked to which.

17. Charges on ions • For most of Group A elements, location on the Periodic Table can tell what kind of ion they form • Elements in the same group have similar properties. • Including the charge when they are ions.

18. Charge in groups 1A, 2A and 3A is the group number 1+ in 5A, 6A and 7A is the group number - 8 2+ 3+ 3- 2- 1-

19. F Can also use electron dots K • If it has a few it loses them • If it has many, it gains enough for octet + -

20. Naming ions • Cation- if the charge is always the same (Group A) just write the name of the metal. • Most transition metals can have more than one type of charge. • Indicate the charge with Roman numerals in parenthesis. • Co2+ Cobalt(II) ion

21. Naming ions • A few, like silver, zinc and cadmium only form one kind of ion • Don’t get roman numerals • Ag+ silver ion • Zn2+ zinc ion • Cd2+ cadmium ion

22. Name these • Na1+ Sodium ion • Ca2+ Calcium ion • Al3+ Aluminum ion • Fe3+ Iron(III) ion • Fe2+ Iron(II) ion • Pb2+ Lead(II) ion • Li1+ Lithium ion

23. Write Formulas for these K1+ • Potassium ion Mg2+ • Magnesium ion Cu2+ • Copper(II) ion Cr6+ • Chromium(VI) ion Ba2+ • Barium ion Hg2+ • Mercury(II) ion

24. Naming Anions • Anions are always the same • Change the element ending to – ide • F1- Fluoride ion

25. Name these • Cl1- Chloride ion • N3- Nitride ion • Br1- Bromide ion Oxide ion • O2- Gallium ion • Ga3+

26. Write these • Sulfide ion S2- • Iodide ion I1- • Phosphide ion P3- • Strontium ion Sr2+

27. Polyatomic ions • Groups of atoms that stay together and have a charge. • Covalently bonded • You must memorize these. (pg 257)

28. 1- ions • Acetate C2H3O21- • Nitrate NO31- • Nitrite NO21- • Hydroxide OH1- • Permanganate MnO41- • Cyanide CN1-

29. 1- ions • Perchlorate ClO41- • Chlorate ClO31- • Chlorite ClO21- • Hypochlorite1-

30. 2- ions • Sulfate SO42- • Sulfite SO32- • Carbonate CO32- • Chromate CrO42- • Dichromate Cr2O72- • Silicate SiO32-

31. 3- ions • Phosphate PO43- • Phosphite PO33- 1+ ion • AmmoniumNH41+

32. Adding Hydrogen to Polyatomics • Hydrogen ions are 1+ • Attach to other polyatomic ions- changes charge by one • Sulfate SO42- • Hydrogen sulfate HSO41- • Phosphate PO43- • Hydrogen phosphate HPO42- • Dihydrogen phosphate H2PO41-

33. Naming Binary Ionic Compounds • Binary Compounds - 2 elements. • Ionic - a cation and an anion. • The name is just the names of the ions. • Cation first anion second • Easy with Group A elements. • NaCl = Na+ Cl- = sodium chloride • MgBr2 = Mg2+ Br- = magnesium bromide • Na2S

34. Naming Binary Ionic Compounds • The problem comes with the transition metals. • Cation name includes the charge. • The compound must be neutral. • same number of + and – charges. • Use the negative charge to find the charge on the positive ion.

35. Naming Binary Ionic Compounds • Write the name of CuO • Need the charge of Cu • O is 2- • copper must be 2+ • Copper(II) oxide • Name CoCl3 • Cl is 1- and there are three of them = 3- • Co must be 3+ • Cobalt(III) chloride

36. Naming Binary Ionic Compounds • Write the name of Cu2S. • Since S is 2-, the Cu2 must be 2+, so each one is 1+. • copper(I) sulfide • Fe2O3 • Each O is 2- 3 x 2- = 6- • 2 Fe must = 6+, so each is 3+. • iron(III) oxide

37. Naming Binary Ionic Compounds • Write the names of the following • KCl • Na3N • CrN • Sc3P2 • PbO • PbO2 • Na2Se

38. Ternary Ionic Compounds • Will have polyatomic ions • At least three elements (3 capital letters) • Still just name the ions • NaNO3 • CaSO4 • CuSO3

39. Ternary Ionic Compounds • (NH4)2O • Fe(OH)3 • LiCN • (NH4)2CO3 • NiPO4

40. Writing Formulas • The charges have to add up to zero. • Get charges on pieces. • Cations from name or periodic table. • Anions from periodic table or polyatomic. • Balance the charges by adding subscripts. • Put polyatomics in parenthesis if there is more than one of them

41. Writing Formulas • Write the formula for calcium chloride. • Calcium is Ca2+ • Chloride is Cl1- • Ca2+Cl1- would have a 1+ charge. • Need another Cl1- • Ca2+Cl21-

42. Crisscross • Switch the numerical value of the charges Ba2+ N3- 3 2 Ba3 N2 • Reduce ratio if possible

43. Write the formulas for these • Lithium sulfide • tin (II) oxide • tin (IV) oxide • Copper (II) sulfate • Iron (III) phosphide • gallium nitrate • Iron (III) sulfide • ammonium sulfide

44. Write the formulas for these • Ammonium chloride • barium nitrate

45. Things to look for • If cations have (), the number is their charge. Not how many. • If anions end in -ide they are probably off the periodic table (Monoatomic) • If anion ends in -ate or -ite it is polyatomic • The positive piece always gets written first • Hydrogen- it depends on where it’s at • If it is second, it’s a nonmetal -hydride

46. Molecular Compounds Writing names and Formulas

47. Molecular compounds • made of just nonmetals • smallest piece is a molecule • can’t be held together because of opposite charges. • can’t use charges to figure out how many of each atom

48. Easier • Ionic compounds use charges to determine how many of each. • Have to figure out charges. • Have to figure out numbers. • Molecular compounds name tells you the number of atoms. • Uses prefixes to tell you the number

49. Prefixes • 1 mono- • 2 di- • 3 tri- • 4 tetra- • 5 penta- • 6 hexa- • 7 hepta- • 8 octa- • 9 nona- • 10 deca-

50. Naming • To write the name write two words • Exception - we don’t write mono- if there is only one of the first element. • No ao oo double vowels when writing name, io, oi, and ai are okay. Prefix name Prefix name -ide