moles/stoichiometry.....aim 1

how are compounds represented?

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aim 2.....

 

HW From textbook “CHEMISTRY a Contemporary Approach” 

·         Read “Chemical formulas” p146-154

·         Do all exercises p148-154

·         Do questions for review 1, 3, 6, 9, 11, 13, 14, 15 p162&163

 

A chemical compound can be represented by a specific chemical formula and assigned a name based on the IUPAC (International Union of Pure and Apply Chemistry)

 

Binary ionic compounds

When a metal and a nonmetal form a binary ionic compound, the metallic element is usually written first and the name of the nonmetal ends in -ide.

Example/problems

 

Name

Ions

Formula

potassium chloride

K+ and Cl-

KCl

calcium chloride

Ca2+ and Cl-

CaCl2

 

Na+ and S2-

Na2S

 

BaS

magnesium oxide

Al3+ and S2-

Li3N

beryllium oxide

 

 

 

 

 

 

 

 

 

 

 

 

Ionic compounds with more than two elements have at least one polyatomic ion . See table E

Example

Sodium carbonate as the name suggests is composed of sodium and carbonate. Sodium is Na+ and carbonate is  CO32-  To keep neutrality, 2 metallic ions Na+ are bonded to one CO32- carbonate.

Sodium carbonate = Na2CO3

Example

Magnesium nitrate as the name suggests is composed of magnesium and nitrate. Magnesium is Mg2+ and nitrate is NO3-   To keep neutrality, 2 nitrates are needed for every Mg2+  

Magnesium nitrate = Mg(NO3)2

 

Note: When more than one polyatomic ion are needed parenthesis are used

 

Problems

Name

Ions

Formula

NaNO3

Al3+ and NO3-

ammonium phosphate

Al2(SO3)3

zinc nitrate

     

 

 

 

 

 

 

 

 

 

 

Covalent compounds

When two nonmetals form a covalent compound, the name of the less electronegative element is usually written first and the name of the compound ends in -ide.

Example/problems

Prefix

Number

Formula

Name

mono-

1

CO

Carbon monoxide

di-      

2

CO2

Carbon dioxide

tri-     

3

SO3

Sulfur trioxide

tetra-  

4

N2O4

 

penta-  

5

P2O5

 

hexa-  

6

SCl6

 

hepta-

7

IF7

 

octa-

8

U3O8

 

nona-

9

 

 

deca-    

10

P4O10

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The stock system

When a metal atom has more then one positive oxidation number the stock system is used. In the stock system, a roman numeral follows the positive ion to indicate its oxidation number. The stock system is used for ionic and also covalent compounds.

Example

Iron (II) nitrate is made of iron and nitrate but the iron has more than one oxidation number therefore; the Roman numeral II indicates the oxidation state of iron or +2

Iron (II) nitrate = Fe(NO3)2

Problems

 

 Name

Ions

Formula

 

Fe3+ and NO3-

Fe(NO3)3

copper (I) chlorite

 

 

copper (II) chlorite

 

Cu(ClO2)2

N+ and O2-

N2O5

nitrogen (III) oxide

NO

N4+ and O2-

lead (IV) chromate

 

Problems

Write the chemical formula corresponding to the name of the compound

 

magnesium oxide

lithium bromide

calcium nitride
     

magnesium sulfide

aluminum nitride

cesium sulfide
     

beryllium oxide

strontium sulfide

boron fluoride
     

lithium chloride

beryllium bromide

sodium oxide
     

sodium sulfate

copper (II) chloride

barium nitrate

     

tin (II) fluoride

mercury (I) bromide

tin (II) oxide
     

copper (II) sulfide

lead (II) bromide

tin (IV) iodide
     

cobalt (II) phosphide

tin (II) sulfide

mercury (I) sulfide
     

copper (II) iodide

tin (IV) fluoride

iron (II) phosphide
     

sulfur tetrachloride

xenon trioxide

carbon dioxide
     

boron trifluoride

tetraarsenic decoxide

silicon tetrachloride
     

carbon monoxide

sulfur trioxide

dinitrogen trioxide
     

bismuth trichloride

silver carbonate

potassium hydrogen phosphate
     

lithium carbonate

magnesium hydrogen sulfate

sodium hypochlorite
     

iron (III) nitrate

potassium perchlorate

lead (IV) hydrogen carbonate
     

 

Problems   

Write the name below the chemical formula.

MgS

KBr

Ba3N2
     

K2S

LiBr

Sr3P2
     

Cs2O

RbI

MgO
     

CuS

PbBr4

Pb3N2
     

CuCl2

CuBr

PbO
     

Hg2O

Hg2I2

AuCl3
     

CrS

Cu2S

SnCl2
     

HgF2

CuS

SnI4
     

Hg2Cl2

CuO

Sn3N2
     

SF6

XeF4

PCl3
     

UF6

OF2

ClO2
     

BrCl5

SCl4

PF3
     

Na2CrO4

Ba(CN)2

K2SO4
     

Pb(OH)4

Cu2Cr2O7

Cu(ClO3)2
     

 TEST YOUR UNDERSTANDING

6/07

9 What is the name of the polyatomic ion in the compound Na2O2?    (1) hydroxide         (2) oxalate              (3) oxide                (4) peroxide

36 Which formula represents lead(II) chromate?    (1) PbCrO4             (2) Pb(CrO4)2        (3) Pb2CrO4           (4) Pb2(CrO4)3

1/06

8 What is the chemical formula for sodium sulfate?    (1) Na2SO3     (2) Na2SO4     (3) NaSO3    (4) NaSO4

6/06

6 What is the IUPAC name for the compound FeS?    (1) iron(II) sulfate     (2) iron(III) sulfate     (3) iron(II) sulfide    (4) iron(III) sulfide

8/06

6 A compound is made up of iron and oxygen, only. The ratio of iron ions to oxide ions is 2:3 in this compound. The IUPAC name for this compound is    (1) triiron dioxide     (2) iron(II) oxide     (3) iron(III) oxide    (4) iron trioxide

1/05

68 Write an IUPAC name for the compound N2O5.

6/05

36 Which substance has a chemical formula with the same ratio of metal ions to nonmetal ions as in potassium sulfide? 	(1) sodium oxide (2) sodium chloride (3) magnesium oxide (4) magnesium chloride

1/04

6 What is the correct formula for iron (III) phosphate? (1) FeP (3) FePO4 (2) Fe3P2 (4) Fe 3(PO4)2

6/03

19. Which formula correctly represents the composition of iron (III) oxide? (1) FeO3  (2) Fe2O3 (3) Fe3O (4) Fe3O2

26. In which substance does chlorine have an oxidation number of +1? (1) Cl2  (2) HCl  (3) HClO  (4) HClO2

8/03

6 What is the correct IUPAC name for the compound NH4Cl?  (1) nitrogen chloride (2) nitrogen chlorate (3) ammonium chloride (4) ammonium chlorate

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