Transcript Notes One Unit Four

Unit One
Notes #1 Unit One
•
•
•
•
•
•
•
Two Classes of Elements
Periodic Table Info?
What Are Stable Elements?
Oxidation/Reduction
Oxidation Numbers
Key Elements and Examples
Pgs 158-165
Draw a picture of an Atom
For a chemical RXN
to occur, two atoms
MUST collide. Since
the electrons are on
the outside, then it is
only the electrons
that are involved !!!
Electrons are either LOST
OR GAINED
Two Classes of Elements
• What are the Two Main Classes of Elements?
• Metals and Nonmetals (Stair-Step)
What information doe the
Periodic Table give us?
Atomic Number
# Protons = # of Electrons
Mass Number = # P + # N
Electron
structure
So any Atom as no charge
• The atomic number tells us the number of
protons (+ charges) AND the number of
electrons (- charges) .
• If you add all the charges up in an atom,
they will equal ZERO.
• An ATOM has NO NET Charge !!!
If we start with an Atom…..
• And it gains electrons, what happens to its’
charge?
• It becomes negative
• And it loses electrons, what happens to its’
chare?
• It becomes positive.
• If an atom becomes + or – we call it an
ION
We can only change the # of
electrons
• If we were to try to change the number of
protons, in the nucleus ….things have a
tendency of going BOOM ! That is a
nuclear reaction. So most chemical
reactions involve the LOSS or GAIN of
electrons
• OXIDATION = Loss of electrons
• REDUCTION = Gain of electrons
What Makes Elements Stable?
•
•
•
•
•
•
Eight Electrons…… we will see this often
Noble Gases (electronically stable)
He, Ne, Ar, Kr, Xe, and Rn
Lose or Gain to get 8e-1 (to become stable)
Do metals Lose or Gain electrons?
Do nonmetals Lose or Gain electrons?
(Lose)
(Gain)
Oxidation Numbers
• All elements Lose or Gain e-1.
• Some have multiple loss or gain possibilities.
Fe+2
Fe+3
S-2
S+4
S+6
Key Elements
•
•
•
•
•
•
•
•
(99%) H+1
H-1
(99%)O-2
O-1
(Always) Li+1, Na+1, K+1, Rb+1, Cs+1, Fr+1
(Always) Be+2, Mg+2, Ca+2, Ba+2, Sr+2, Ra+2
(Always) Al+3
(with only a metal) F-1, Cl-1, Br-1, I-1
(NO3-1) ion is always +5
(SO4-2) ion is always +6
Example One
• Find the oxidation numbers.
• Al2S3
• Algebra is useful!
2(Al) + 3(S)= 0
• Al+3 key element
• 2(+3) + 3(S)=0
• S= -2
Example Two
• Find the oxidation numbers.
• Ca(NO3)2
• Algebra is useful !
(Ca)+ 2(N)+ 6(O)= 0
• Ca+2 and O-2 key elements
• (+2)+2(N)+6(-2)=0
• (+2)+2(N)+(-12)=0
• 2(N)+(-10)=0
• 2(N)=10
• N= +5
Finding Oxidation #’s for Compounds
+1 -2
H2O
+1+4 -2
H2CO3
+1+5 -2
H3PO4
-3 +1+4 -2
(NH4)2CO3
+2 +5 -2
Ca3(AsO4)2
+3 +6 -2
Fe2(SO4)3
+2 +7 -2
Ba(ClO4)2
+1+5 -2
HNO3
+1+6 -2
H2SO4
+1 +6 -2
Hg2SO4
+1 +6 -2 +3 +4 -2
Na2Cr2O7 Al2(CO3)3
Now it is time for class work !!!
• A101: paper practice (Work Together)
• It will be due at beginning of class next
time
• Ready Set Break !!!
So Let’s Review
• When we are assigning oxidation
numbers:
If we are dealing with a molecule and there
is no charge, the sum of all the oxidation
numbers will add to zero.
If we are dealing with a Polyatomic ion, then
the sum of all of the oxidation numbers
adds up to that charge
+2 +5 -2
+6 -2
Ca3(PO4)2
Cr2O7 -2
CA101 Assigning oxidation #’s
Turn on Mac: double click on the MAC folder on the desktop. Open the
Redox folder and click on the yellow, red and blue icon.
Choose the top button: finding oxidation
Numbers in triatomic compounds.
You will do 15 problems and show all your algebra work on CA101 !!!!!
I will show you how today.
If you click on KEY ELEMENTS Your resource paper is online in
The program.
Please get A101 and CA 101
Stamped Today !!!
Once you are done we will intro
Formula Writing
Notes Two Unit One
•
•
•
•
•
Naming Inorganic Salts
Example One
Example One Thinking
Example Two
Computer Assignment One
Naming Inorganic Salts
•
•
•
•
•
•
•
•
•
•
•
•
•
TWO parts to the name
1) Cation Positive
2) Anion Negative
Cation Examples
Ca+2
Al+3
Fe+2
Na+1
Anion Examples
Cl-1
NO3-1
SO4-2
N-3
Example One
• Name the formula Fe2(CrO4)3
• Step #1 Find The + Ion(s).
Iron(II) Fe+2
Iron(III) Fe+3
Example One
• Step #2 Find The - Ion(s)
Chromate CrO4-2
Example One
Fe2(CrO4)3
Fe+2 Iron(II) Fe+3 Iron(III) CrO4-2Chromate
Iron(II) Chromate
Iron(III) Chromate
Fe+2
Fe+3
CrO4-2
X (+2) + Y (-2) = 0
X=1
Y=1
1 (+2) + 1 (-2) = 0
FeCrO4
CrO4-2
X (+3) + Y (-2) = 0
X=2
Y=3
2 (+3) + 3 (-2) = 0
Fe2(CrO4)3
Example Two
Al2(CO3)3
Al+3 Aluminum CO3-2 Carbonate
Aluminum Carbonate
Al+3
CO3-2
X (+3) + Y (-2) = 0
X=2
Y=3
2 (+3) + 3 (-2) = 0
Al2(CO3)3
In class work today:
• Work on A102
• Use you Cation/Anion Sheet
• Remember to fnd the charges of the ions
and make sure that they add up to zero to
write the formula.
• When you are naming a formula you
always write the + ion first then the -ion
CA 102:Writing Formula
CA 103: Naming Compounds
• NAMING IONIC COMPOUNDS LEVELs ONE AND TWO
• Get A102 , CA 102, CA103 all stamped today.
• Now let’s look at some examples at how to write Formulas
from a name. You need to have your Cation/Anion sheet
out.
• Homework for tonight, read L101 Electrolysis of
water Lab, we will do that next class !!!!
Writing a Formula From a Name
X (+?) + Y (-?) = 0
(Cation+?)X(Anion-?)Y
If X or Y is 2 or greater...
and the ion is polyatomic.
Ba+2 Cr2O7-2 Hg2+2
Lowest Whole Number Ratio
Pb+4
Lithium Nitrate
(Li+1 )_(
1 NO3-1 )_
1
Hydrogen Phosphate (H+1 )_(
3 PO4-3 )_
1
Ammonium carbonate ( NH4+1 )_(
1
2 CO3-2)_
Calcium Arsenate
(Ca+2)_(
2
3 AsO4-3 )_
Iron(III) periodate
(Fe+3)_(
1 IO4-1 )_
3
Mercury(I) Sulfate
(Hg2+2)_(
2 SO4-2 )_
2
Barium Perchlorate (Ba+2 )_(
2
1 ClO4-1 )_
Sodium Dichromate (Na+1)_(
1
2 Cr2O7-2 )_
Lead(IV) Sulfate
(Pb+4)_(
4
2 SO4-2 )_
LiNO3
H3PO4
(NH4)2CO3
Ca3(AsO4)2
Fe(IO4)3
Hg2SO4
Ba(ClO4)2
Na2Cr2O7
Pb(SO4)2
Notes Three Unit One
•
•
•
•
•
•
Standard Amounts
One Gopher
One Mole
Formula mass
Percent Composition
Empirical Formula
Standard Amounts
How many dollars is…
A) 120 pennies?
1.2 dollars
B) 2 quarters?
0.5 dollars
C) 15 nickels?
0.75 dollars
How many dozens is…
D) 48 eggs?
4 dozen
E)18 apple fritters
1.5 dozen
One Dozen
You KNOW it equals 12
items
What if I asked you to
Go into the lab and get
12 Carbon atoms?
One Mole
One mole is 6.022x10+23 items.
Each element on the period
table has a mass per mole.
N 14.0g 6.022x10+23atoms
O 16.0g 6.022x10+23atoms
C 12.0g 6.022x10+23atoms
How many moles are in each?
How many atoms are in each?
N 7.0g ÷14.0g/m =0.50m x6.022x10+23atoms/m =3.01x10+23atoms
O 4.0g ÷16.0g/m =0.25m x6.022x10+23atoms/m =1.51x10+23atoms
C 18.0g÷12.0g/m=1.50m x6.022x10+23atoms/m =9.03x10+23atoms
Calculations Bases on Chemical Formulas
•Formula mass (Molecular Mass or Gram-Formula Mass)
•Empirical Formula
•Percent Composition
Rounding Atomic Mass
C 12.011
Fe 55.847
O 15.9994
Bi 208.980837
K 39.0983
Au 196.96654
Os 190.23
Mg 24.3050
Na 22.98968
12.0
55.8
16.0
209.0
39.1
197.0
190.2
24.3
23.0
Formula Mass Example One
Calculate the formula mass for 1 mole of C6H12O6.
E
C
H
O
#
Mass
6 x 12.0 = 72.0
12 x 1.0 = 12.0
6 x 16.0 = 96.0
180.0g/mol
12.011
1.0079
15.9994
How many molecules of C6H12O6 is 180.0g/mol?
6.022x10+23 molecules
Empirical Formula
• By definition, it is the lowest WHOLE
number ratio of elements in a compound.
• It may or may not be the actual
MOLECULAR FORMULA.
• But is does so the whole number ratio of
elements in a compound.
• HO = empirical formula of Hydrogen
Peroxide but H2O2 is the molecular
Formula
Empirical Formula Example One
What is the empirical (simplest) formula containing
36.8% N, 63.2% O?
1) Calculate moles of each element.
Q
Mass
E
Mass
N 36.8 g ÷ 14.0 = 2.63 mol N
14.0067
15.9994
O 63.2 g ÷ 16.0 = 3.95 mol O
2) Calculate the lowest ratio. (divide by small moles)
Moles Lowest Ratio
E
N 2.63 mol N ÷ 2.63 mol = 1.00
O 3.95 mol O ÷ 2.63 mol = 1.50
3) Write the formula
N2O3
X by 2 to get
whole numbers
Percent Composition Example One
Calculate the percentage composition of H2O.
1)Calculate the formula mass for 1 mole of H2O
E #
Mass
H 2 x
1.0 = 2.0
1.0079
O 1 x 16.0 = 16.0
15.9994
18.0g/mol
2) Divide each contribution by the total mass.
H 2.0 ÷ 18.0 =(0.11 x 100) = 11%
O 16.0 ÷ 18.0 =(0.889 x 100) = 88.9%
3) Add the percentages to check work.
11%
88.9%
100.%
Answer
Empirical Formula Example Two
What is the empirical (simplest) formula containing
69.58% Ba, 6.090% C, 24.32% O?
1) Calculate moles of each element.
Q
Mass
E
Mass
Ba 69.58 g ÷ 137.33 = 0.50666 mol Ba
C 6.090 g ÷ 12.01 = 0.50708 mol C
O 24.32 g ÷ 16.00 = 1.520 mol O
2) Calculate the lowest ratio.
E
Moles Lowest Ratio
Ba 0.50666 mol ÷ 0.50666 mol =1.000
C 0.50708 mol ÷ 0.50666 mol =1.001
O 1.520 mol ÷ 0.50666 mol =3.00
3) Write the formula
BaCO3
X by 1 to get
whole numbers
Percent Composition Example Two
Calculate the percentage composition of Fe(ClO4)3.
1)Calculate the formula mass for 1 mole of Fe(ClO4)3.
E #
Mass
55.847
Fe 1 x 55.8 = 55.8
35.453
Cl 3 x 35.5 = 106.5
15.9994
O 12 x 16.0 = 192.0
354.3g/mol
2) Divide the each contribution by the total mass.
Fe 55.8 ÷ 354.3 = ( 0.1575 x 100) = 15.8%
Cl 106.5 ÷ 354.3 = ( 0.3006 x 100) = 30.06% Answer
O 192.0 ÷ 354.3 = (0.5419 x 100) = 54.19%
3) Add the percentages to check work.
15.8 %
30.1 %
54.2 %
100.1%
Formula Mass Example Three
Calculate the formula mass for 1 mole of Al2O3
E
Al
O
#
Mass
2 x 27.0 = 54.0
3 x 16.0 = 48.0
102.0g/mol
26.98154
15.9994
How many molecules of Al2O3 is102.0g/mol?
6.022x10+23 molecules
Formula Mass Example Two
Calculate the formula mass for 1 mole of CaCO3.
E
Ca
C
O
#
Mass
1 x 40.1 = 40.1
1 x 12.0 = 12.0
3 x 16.0 = 48.0
100.1g/mol
40.078
12.011
15.9994
How many molecules of CaCO3 is100.1g/mol?
6.022x10+23 molecules