Chem 105X
Fri. Sept. 16, 2011
The charge on a cesium ion is..
Cs atom 
+1
55 p+
55 p+
55 e54 e78 n
78 n
Cs+
e-
30
3
1
2
2
3
0
-2
-1
0
+1
+2
-1
1) Formulas and names
2) Mixed nomenclature
3) Calculations: moles - grams
1.
2.
3.
4.
5.
107
-2
Today
Being able to expose a misconception - and
then hopefully correct it - is one of the
benefits of using clickers.
In this case, it was suggested that the “-1”
answer came from thinking that cesium ions
arise via the process “cesium atom minus
an electron”.
That process is correct, however one would
not want to take “minus” literally!
1
A common error in
student “written”
answers:
They show units in
the answer, but not
in the work leading
up to the answer.
For full credit, units
are required BOTH
in the WORK and in
the ANSWER.
The “unit
conversion factor
method” is the best
way to solve many
practical science
and engineering
problems.
metric
2
Laboratory next week
Introduction to Measurement Glassware
and Use of Excel for Numerical Analysis
3
Name of element
REVIEW: Monatomic ions
Root of element+”ide”
1+ 2+
3- 2- 13+
Name of element + (I) or (II) ..
1+ to 4+
2+
4
Naming Ionic Compounds
Name  Formula
Formula  Name
5
Naming Ionic Compounds
 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’s always +2
NaF sodium fluoride
K2O potassium oxide
lithium nitride Li3N
CoI2 cobalt (II) iodide
ZnI2 zinc iodide
6
OWL and the text differ on name of the Ni2+ ion.
Kotz calls it “nickel (II)”
OWL names this ion “nickel” (because 2+ is essentially
the only ion formed by Ni)
On OWL, use “nickel”.
On exams, if Ni is used, EITHER NAME will be acceptable.
e.g.
NiBr2
is nickel bromide or nickel (II) bromide
7
Polyatomic ions - like a molecule, but with total charge > or < 0.
All but two contain O, so they are called “oxoanions”. At this point, without getting into a
lot of bonding theory etc, this is pretty much brute force memorization. However, there are
useful trends that make it pretty easy to remember these ions, names, and charges.
+1
-1
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)
-2
-3
CO32- (carbonate)
PO43- (phosphate)
SO32- (sulfite)
SO42- (sulfate)
CrO42- (chromate)
Cr2O72- (dichromate)
HPO42- (hydrogen
phosphate)
8
You need to KNOW NAMES and FORMULAS of the
polyatomic ions on previous table. This is your chemistry
vocabulary. p. 75 And Oxoanion Table on the course
website.
9
Ionic compounds with polyatomic ions
Need to RECOGNIZE POLYATOMIC ION(s) within the
formula.
NaNO2 contains one Na+ and one NO2(nitrite) ion per formula unit.
NH4NO2 contains one NH4+ (ammonium) and
one NO2- ion per formula unit.
10
Calcium phosphate
(Always)
Ca2+
(on board)
(Always) PO43-
Balance charge using
lowest integer ratio: 3:2
Ca3(PO4)2
11
Names include Roman numerals 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
12
REQUIRED
Copper (I) hydrogen carbonate
Leave on
board
Or Copper (I) bicarbonate
Therefore, this
must be the
Cu+ cation
HCO3- anion
CuHCO3
13
In the formula of iron (II) sulfate, what is the
subscript of Fe?
129
30
4
3
2
1
ho
w
n)
12
ts
1 (not shown)
2
3
4
1(
no
1.
2.
3.
4.
(Sulfate is SO42-. So for each sulfate, you just need
ONE Fe2+ to achieve electric neutrality (# + = # -.
I.e, FeSO4.)
14
The formula of the compound calcium chlorite is...
CaCl
CaCl2
CaClO2
Ca(ClO2)2
83
42
37
O2
)2
Ca
(C
l
lO
2
Ca
C
l2
Ca
C
l
6
Ca
C
1.
2.
3.
4.
(Chlorite is ClO2-. Calcium ion is Ca2+. So you need
TWO chlorites to achieve electric neutrality.
I.e, Ca(ClO2)2 .)
15
Binary (2-element) covalent compounds
16
Covalent compounds are
formed by non-metal elements.
17
“Binary” Covalent compounds - contain
2 elements. The relative number of
atoms is in general NOT
PREDICTABLE. (look at all the “carbon
oxides” known…)
CO
CO2
C2O
C3O
etc
Names: DO INCLUDE PREFIXES that
reflect the # of atoms. The 2nd atom is
named like the monatomic ion (but its
not an actual ion in the molecule…)
Carbon monoxide
Carbon dioxide
Dicarbon monoxide
Tricarbon monoxide
The element to RIGHT on the periodic
table goes 2nd in the name.
18
Interstellar dust clouds contain many unusual molecules..
http://en.wikipedia.org/wiki/List_of_molecules_in_interstellar_space
19
Mixed nomenclature
Detecting “covalent” vs. “ionic” compounds
OWL 2.8d
20
No metal or “NH4”! Therefore covalent
What is the name of the compound with the formula SO 3?
Sulfur trioxide
What is the name of the compound with the formula KNO 3?
Potassium nitrate
Group I metal is ALWAYS 1+!
Therefore ionic.
What is the formula for nickel chloride?
This transition metal is ALWAYS 2+!
Therefore ionic.
NiCl_2_
What is the formula for boron trichloride?
BCl_3_


No metal or “NH4”! Therefore covalent
21
Moles/grams calculations
22
Molar mass (also called molecular weight)
Molar mass = Sum of atomic weights of all atoms in formula
= mass of 1.00 mole of the compound in grams
Units: grams/mole
(abbreviated g/mol)
Molar mass of lithium phosphate = ?
Li3PO4
M(Li3PO4) = 3(6.941g/mol) + 30.934g/mol + 4(15.999g/mol)
M(Li3PO4) = 99.75 g/mol
23
Hint:
Use OWL’s periodic table and atomic masses when
doing chemical calculations in OWL.
(Atomic weights sometimes are different on different
tables, but OWL assumes you’re using the OWL
periodic table.)
24
Practice problem using mole and molar mass
25
Acetonitrile, CH3CN, is a common solvent, and interstellar
molecule. How many moles of acetonitrile (“AN”) are contained
in 2.50 kg AN?
H
On board

initial data  

 
  
 

2.50 kg AN  


...  final

 
  
 
H
C
C
N
H
Molar mass =
41.0527 g/mol

  ? moles AN


  moles AN 
  
  ? moles AN
2.50 kg AN  
 kg AN  


  1 mole AN 

  
  ? moles AN
2.50 kg AN  
 kg AN   41.0527 g AN 
The molar mass
26

  1 mole AN 
  
  ? moles AN
2.50 kg AN  
 kg AN   41.0527 g AN 
 1103 g AN   1 mole AN 
  
  ? moles AN
2.50 kg AN  
 kg AN   41.0527 g AN 
The metric
conversion factor
 1103 g AN   1 mole AN 
  
  60.8973 moles AN
2.50 kg AN  
 kg AN   41.0527 g AN 
60.9 moles AN
27
The End
28