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Nomenclature

Nomenclature

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Nomenclature

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  1. Nomenclature A systematic method of writing chemical formulas and naming compounds

  2. Chemical symbols • Symbols are used to represent elements • Either one capital letter, or a capital letter with a lower case letter • Know names and symbols of elements: • 1 – 30, plus • Rb, Cs, Sr, Ba, Ag, Au, Cd, Hg, Pt, Sn, Pb, Br, I, and U

  3. Chemical formulas • Formulas are used to represent compounds • All formulas have more than one symbol • Two or more capital letters • All chemical names have two words • No need to capitalize words in name

  4. I. Binary Ionic nomenclature • Binary = two elements • Ionic means cation and anion • Cations (+ ions) are usually metals • Anions (- ions) are usually nonmetals • Therefore: • Two elements, one metal and one nonmetal

  5. a) naming them • Name the metal • Name the nonmetal, changing the ending to “ide” • Example: name MgCl2 • Mg = magnesium • Cl = chlorine, so write “chloride” • Name is magnesium chloride

  6. Name these • NaF • Na is sodium • F is fluorine, so write fluoride • sodium fluoride • Al2O3 • Al is aluminum • O is oxygen, so write oxide • aluminum oxide

  7. Name these • Ca3P2 • Ca is calcium • P is phosphorus, so write phosphide • calcium phosphide • K3N • K is potassium • N is nitrogen, so write nitride • potassium nitride

  8. Name these • BaS • Ba is barium • S is sulfur, so write sulfide • barium sulfide • SrI2 • Sr is strontium • I is iodine, so write iodide • strontium iodide

  9. Name these • Mg3N2 • Mg is magnesium • N is nitrogen, so write nitride • Magnesium nitride • BeI2 • Be is beryllium • I is iodine, so write iodide • beryllium iodide

  10. Nomenclature A systematic method of writing chemical formulas and naming compounds

  11. I. Binary Ionic nomenclature • Binary = two elements • Ionic means cation and anion • Cations (+ ions) are usually metals • Anions (- ions) are usually nonmetals • Therefore: • Two elements, one metal and one nonmetal

  12. a) naming them • Name the metal • Name the nonmetal, changing the ending to “ide” • Example: name MgCl2 • Mg = magnesium • Cl = chlorine, so write “chloride” • Name is magnesium chloride

  13. Name these • BaS • Ba is barium • S is sulfur, so write sulfide • barium sulfide • SrI2 • Sr is strontium • I is iodine, so write iodide • strontium iodide

  14. b) Writing formulas • Notice: subscripts in the name did not effect the naming of these compounds • So, where do the subscripts come from? • Why are they there? • The subscripts are there to balance charges **ALL IONIC COMPOUNDS ARE NEUTRAL** • The subscripts tell us how many of each element are present in the finished formula Example: Al2S3 means 2 aluminums and three sulfurs in one “formula unit”

  15. b) Writing formulas • Write the symbol for each ion • the element and its charge • Balance the charges • The total (+) charge must equal the total (-) charge • “criss cross” • Re-write the formula without any charges

  16. Write the formula for: • barium phosphide • barium is Ba, the charge is 2+ (column 2A) • phosphide was phosphorus, so P; charge is 3- (column 5A) • Ba2+P3- • Criss-cross to balance charges (2+ with 3-) • Ba3P2

  17. Write the formula for: • sodium bromide • Sodium is Na, the charge is 1+ (column 1A) • Bromide was bromine, so Br; charge is 1- (column 7A) • Na+Br- • Charges are already balanced (1+ with 1-) • Re-write as NaBr

  18. Write the formula for: • calcium iodide • calcium is Ca, the charge is 2+ (column 2A) • iodide was iodine, so I; charge is 1- (column 7A) • Ca2+I- • Criss-cross to balance charges (2+ with -) • Ca1I2 • Re-write as CaI2

  19. Write the formula for: • potassium phosphide • potassium is K, the charge is 1+ (column 1A) • phosphide was phosphorus, so P; charge is 3- (column 5A) • K+P3- • Criss-cross to balance charges (+ with 3-) • K3P1 • Re-write as K3P

  20. Write the formula for: • magnesium oxide • magnesium is Mg, the charge is 2+ (column 2A) • oxide was oxygen, so O; charge is 2- (column 6A) • Mg2+O2- • Charges are already balanced (2+ with 2-) • Re-write as MgO

  21. Special case • Zinc (Zn) is always a 2+ ion • Silver (Ag) is always a 1+ ion • These must be memorized

  22. II. Transition metal ionic nomenclature • Transition metals form several possible cations • Example: manganese (Mn) is found as 2+, 3+, 4+, 5+, 6+ and 7+ ion! • There is no compound just called “manganese oxide” – there are at least four compounds that are different manganese oxides • Different charges result in differentsubscripts

  23. II. Transition metal ionic nomenclature • Iron is commonly found as both Fe2+ and Fe3+ • Fe2+ is called iron(II) • Fe3+ is called iron(III) • and,… • Cu+ is called copper(I) • Cu2+ is called copper(II), etc…

  24. II. Transition metal ionic nomenclature • Lead (Pb) and tin (Sn) behave like the transition metals, and therefore follow the same rules • Pb2+ is lead(II) • Sn4+ is tin(IV) • Zinc and silver DO NOT follow these rules, because zinc is always Zn2+ and silver is always Ag+

  25. a) Writing formulas • Follow the same rules as the other ionic compounds • Iron(II) oxide is • Fe2+O2- • Charges balance, so formula is FeO • Iron(III) oxide is • Fe3+O2- • Criss cross to balance charges • Fe2O3

  26. Write the formula for: • vanadium(III) oxide • vanadium is V, the charge is 3+(roman numeral III) • oxide was oxygen, so O; charge is 2- (column 6A) • V3+O2- • Criss cross to balance charges (3+ with 2-) • Re-write as V2O3

  27. Write the formula for: • Cobalt (II) iodide • Cobalt is Co, the charge is 2+(roman numeral II) • iodide was iodine, so I; charge is 1- (column 7A) • Co2+I- • Criss cross to balance charges (2+ with 1-) • Re-write as CoI2

  28. Write the formula for: • Lead(IV) sulfide • lead is Pb, the charge is 4+ (roman numeral IV) • sulfide was sulfur, so S; charge is 2- (column 6A) • Pb4+S2- • Criss cross to balance charges (4+ with 2-) • Re-write as Pb2S4 • Reduce subscripts!! PbS2

  29. b) Writing names • Same rules as other ionic compounds, except… • You must write a roman numeral in parentheses after the name of the metal to show what the positive charge on the metal is • Only do this with transition metals • And Pb, Sn • But not Zn, Ag

  30. Name these • NiCl2 • Ni is nickel, and it is a transition metal • Cl is chlorine, so write chloride • nickel( ? ) chloride • But, what is the roman numeral? • Note: uncriss cross subscripts to determine charges • Ni2+Cl- • nickel(II) chloride

  31. Name these • CuS • Cu is copper, and it is a transition metal • S is sulfur, so write sulfide • copper( ? ) sulfide • But, what is the roman numeral? • Note: no subscripts, so charges are balanced • S is always 2-, so the copper in this compound must be 2+ ! • copper(II) sulfide

  32. Name these • Cu3N • Cu is copper, and it is a transition metal • N is nitrogen, so write nitride • copper( ? ) nitride • But, what is the roman numeral? • Note: subscripts, so charges are not balanced • copper(I) nitride

  33. Name these • Co3P2 • Co is cobalt, and is a transition metal • P is phosphorus, so write phosphide • cobalt(?) phosphide • But, what is the roman numeral? • Note: un-crisscross subscripts to determine charges • Co2+P3- • cobalt(II) phosphide

  34. Name these • PbO2 • Pb is lead, and it behaves like transition metals • O is oxygen, so write oxide • lead( ? ) oxide • But, what is the roman numeral? • Note: subscripts show charges are not balanced • lead(II) oxide, right? • NO!

  35. Name these • PbO2 • Careful - O is oxide – and is always 2- • So the total (-) charge is 4-! • So, what is the roman numeral? • To balance the 4- charge, you need a 4+ charge • lead(IV) oxide, right? • YES!

  36. Be careful… • When the charges become subscripts that can be reduced • Examples: • 4+/2- SnO2 is tin(IV) oxide • 6+/3- CrP2 is chromium(VI) phosphide • 6+/2- MnS3 is manganese(VI) sulfide

  37. Nomenclature A systematic method of writing chemical formulas and naming compounds

  38. III. Polyatomic Ionic nomenclature • Polyatomic ions are groups of atoms covalently bonded together, that act as a single ion • Think of them as lego blocks that have been glued together • Each have a name and charge that must be memorized

  39. Polyatomic ions • Nitrate: NO31- • bicarbonate: HCO31- Image source: wikipedia

  40. Polyatomic ions • carbonate: CO32- • acetate: C2H3O21-or CH3COO- Image source: wikipedia

  41. 1+ ions Ammonium NH4+ 1- ions Nitrate NO3- Hydroxide OH- Bicarbonate HCO3- Permanganate MnO4- Acetate C2H3O2- Polyatomic ions

  42. 2- ions Sulfate SO42- Carbonate CO32- 3- ions phosphate PO43- Polyatomic ions

  43. a) Writing names • Same as before: • Write the name of the cation • Write the name of the anion • Simply write the polyatomic ion’s name as it is, without any changes • Still only two words in the name

  44. NaNO3 • More than two capital letters, so there must be at least one polyatomic ion in the formula • Na is sodium, so… • The entire “NO3 part” must have a one word name: • Nitrate is NO3- • sodium nitrate

  45. Al2(SO4)3 • More than two capital letters, so there must be at least one polyatomic ion in the formula • Al is aluminum, so… • The entire SO4 part must have a one word name: • Sulfate (SO42-) • aluminum sulfate

  46. (NH4)3PO4 • Obviously more than two elements • Look for polyatomic ions • “NH4” is ammonium • “PO4” is phosphate • Ammonium phosphate

  47. b) Writing formulas • Follow the same rules as the other ionic compounds • Iron(II) sulfate is • Fe2+SO42- • Charges balance, so formula is FeSO4

  48. b) Writing formulas • Iron(III) sulfate is • Fe3+ SO42- • Criss cross to balance charges • But: we don’t want Fe2SO43 • There aren’t 43 oxygens! • Use parentheses around polyatomic ion • Fe2 (SO4)3

  49. Write the formula for: • Chromium(III) carbonate • Cr3+ CO32- • Crisscross to balance charges • Cr2(CO3)3

  50. Write the formula for: • Magnesium hydroxide • Mg2+ OH- • Crisscross to balance charges • Mg(OH)2 • you need parentheses around the hydroxide because it is a polyatomic ion, even though it has no subscripts of it’s own.