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Chapter 9

Chapter 9. Naming Compounds Writing Formulas. 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. Periodic Table. More than a list of elements.

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Chapter 9

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  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

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