9/18/2009 1

Chem 105X

Wed. Sept. 18, 2009

Today

Tutors

Laboratory

1)Ionic and Covalent compounds

2)Formulas and names

3)Mixed nomenclature

4)Calculations:

a. moles-atoms-molecules, and all that

9/18/2009 2

Department of Chemistry and Biochemistry

Tutor is Jennifer Chambers

Room 170 Reichardt

Hours: Sept 21 thru Oct 2

Mon 12-2

Tues 2:45-3:45 and 5:15-8:00

Thurs 1-5:15

Fri 12-4

9/18/2009 4

Academic Advising Center’s

Supplemental Instruction (SI) Program

Robert Gorsline

Weekly review session

About 6 office hours, including some on

weekend.

(call 474-6396 for latest schedule)

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Laboratory next week

Introduction to Measurement Glassware and Use of Excel for Numerical Analysis

Please go to the Blackboard website for your lab procedure and pre-lab and lab report form. (demo)

9/18/2009 6

Review (1) monatomic ions1+

2+ 3- 2- 1-

1+ to 4+

Review (2) In compounds, Total + = Total -

9/18/2009 7

The compound between potassium and iodine

contains equal amounts of

K+

and I

- i..

. K

22+

and

I22.

.. K

2+ a

nd I2

- ...

K a

tom

s an

d I2

...84%

5%6%6%

1. K+ and I- ions

2. K22+ and I2

2- ions

3. K2+ and I2- ions

4. K atoms and I2 molecules

9/18/2009 8

The compound between potassium and iodine

contains equal amounts of

1. K+ and I- ions

2. K22+ and I2

2- ions

3. K2+ and I2- ions

4. K atoms and I2 molecules

Ionic compounds contain ions, not

atoms or molecules, which are

uncharged (neutral).

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Naming Ionic Compounds

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� Cation name first…..Anion name

second

� Names DO NOT reflect the relative

numbers

� The relative numbers are INFERRED

from the ION CHARGES

� Transition metals and Sn,Sb,Pb,Bi

require ROMAN NUMERAL to indicate

charge

� Zinc (Zn) does NOT require a roman

numeral – it is always 2+

NaF sodium fluoride

K2O potassium oxide

lithium nitride Li3N

CoI2 cobalt (II) iodide

ZnI2 zinc iodide

9/19/2008 11

OWL and the text differ on name of the Ni2+ ion.

Kotz calls it “nickel (II)”

OWL calls it just “nickel” (because this is essentially the

only ion formed by Ni)

On exam I, if Ni is used, the charge will be

specified, and EITHER NAME will be an

acceptable answer.

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Polyatomic ions - like a molecule, but with total charge > or < 0.

All but two contain O, so they are called “oxoanions”.

+1 -1 -2 -3

NH4+ OH- (hydroxide)

NO2- (nitrite)

NO3- (nitrate)

ClO- (hypochlorite)

ClO2- (chlorite)

ClO3- (chlorate)

ClO4- (perchlorate)

CN- (cyanide)

CH3CO2- (acetate)

MnO4- (permanganate)

HCO3- (hydrogen carbonate)

HSO4- (hydrogen sulfate)

H2PO4- (dihydrogen phosphate)

CO32- (carbonate)

SO32- (sulfite)

SO42- (sulfate)

CrO42- (chromate)

Cr2O7

2- (dichromate)

HPO42- (hydrogen

phosphate)

PO43- (phosphate)

9/18/2009 13

You need to KNOW NAMES and FORMULAS of the

polyatomic ions on previous table. This is your chemistry

vocabulary. Table 2.4 p. 74 And Oxoanion Table on the course website.

Go to website

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http://www.uaf.edu/chem/105Fa08/IonsTable/IonsIndex.htm

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What do these polyatomic anions look like? - Atoms tied together with covalent bonds in a definite geometry (as in a

molecule), but with 1 or more extra electrons.

- We’ll put off a discussion of the details of bonding until later in the semester, but here is a picture of the computed structure of HCO

3

-.

(see hydrogen carbonate

(bicarbonate) in HyperChem)

Approximate outer limit of electrons

The red color means that region is rich in

negative charge (slight excess of electrons). The

blue color indicates a region relatively poor in

electrons, “partially positive” is term sometime

used. The H of the OH group is like this.

9/18/2009 16

Ionic compounds with polyatomic ions obey same rules.

BUT: Need to RECOGNIZE THE ION(s) FROM THE

TABLE within the formula!

NH4NO2 contains one NH4+ and one NO2

- ion

per formula unit.

NaNO2 contains one Na+ and one NO2- ion

per formula unit.

9/18/2009 17

Naming also follows the same rules, including using roman

numeral for transition and lower main group atoms (but not zinc).

Calcium phosphate

(Always) Ca2+ (Always) PO43-

Balance charge using

lowest integer ratio: 3:2

Ca3(PO4)2

9/18/2009 18

Naming also follows the same rules, including using roman

numeral for transition and lower main group atoms (but not zinc).

Iron (III) nitrite

(Always) Fe3+ (Always) NO2-

Balance charge using

lowest integer ratio: 1:3

Fe (NO2)3

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CuHCO3

HCO3- anion

Therefore, this

must be the

Cu+ cation

Copper (I) hydrogen carbonate

Or Copper (I) bicarbonate

REQUIREDREQUIRED

9/18/2009 20

1.0 mole of sodium chloride contains

how many moles of IONS?

1. 2. 3. 4.

35%

1%6%

58%

1. 1.0

2. 2.0

3. 3.0

4. 4.0

9/18/2009 21

1.0 mole of sodium chloride contains

how many moles of IONS?

1. 1.0

2. 2.0

3. 3.0

4. 4.0

Na Cl-

Na Cl-

Na Cl-

Na Cl-

Na Cl-

Na Cl-

Na Cl-

Na Cl-

Na Cl-

Na Cl-

Na Cl-

Na Cl-

A dozen formula

units of NaCl

contains 24 ions

1.0 mole of NaCl contains a mole (6.02x1023) NaCl

formula units. That is, a mole of each ion; total = 2

moles.

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1.0 mole of sodium carbonate contains

how many moles of IONS?

1. 2. 3. 4.

3%

17%

58%

21%1. 1.0

2. 2.0

3. 3.0

4. 4.0

9/18/2009 23

1.0 mole of sodium carbonate contains

how many moles of IONS?

1. 1.0

2. 2.0

3. 3.0

4. 4.0

Na2CO3

9/18/2009 24

Covalent compounds form among non-metal atoms (several exceptions).

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“Binary” Covalent compounds - contain 2 kinds of atoms. The relative number of atoms is in general NOT PREDICTABLE.

So we just work back and forth between name and formula.

Names: DO INCLUDE PREFIX REFLECTING No. of atoms. The 2nd

atom is named like the monatomic ion (but its not an actual ion in the molecule…)

The element to RIGHT on the periodic table goes 2nd.

CO

CO2

C2O2

C3O2

etc

Carbon monoxide

Carbon dioxide

Dicarbon dioxideTricarbon dioxide

9/18/2009 26

Mixed nomenclature

Detecting “covalent” vs. “ionic” compoundsOWL 2.8c

9/18/2009 27

What is the name of the compound with the formula SO3?

What is the name of the compound with the formula KNO3?

What is the formula for nickel chloride?

What is the formula for boron trichloride?

Sulfur trioxide

NiCl_2_

No metal or “NH4”! Therefore covalent

Group I metal is ALWAYS 1+! Therefore ionic.

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This transition metal is ALWAYS 2+!

Therefore ionic.

No metal or “NH4”! Therefore covalent

Potassium nitrate

BCl_3_

9/18/2009 28

What ions – and their relative numbers - are

present in Li2SO4?

1. Two Li2+ and one SO44-

2. Two Li+, one S2-, and two O2 molecules

3. One Li22+, one S2-, and one O4 molecule

4. Two Li+ and one SO42-

5. One Li22+ and one SO4

2-

6. Need more information

9/18/2009 29

What ions – and their relative numbers - are present in Li2SO4?

1. Two Li2+ and one SO44-

2. Two Li+, one S2-, and two O2 molecules

3. One Li22+, one S2-, and one O4 molecule

4. Two Li+ and one SO42-

5. One Li22+ and one SO4

2-

6. Don’t know

(1) In any compound, a Group I metal M always forms M+ ion(2) “SO4” is the sulfate ion SO4

2- (simply by

memorization at this point)(3) No molecules “inside” polyatomic ions.