Facts about the Periodic Table

1
Facts about the Periodic Table

• The current form of the Periodic Table of the
  Elements
• Not Final still being changed by addition of
  elements
• Recent change in numbering of families (columns)
• Suggestions still being made on organization!
• Organization is EXTREMELY important
• Terminology
• Columns (vertical) Groups (families)
• Some groups have names (later) others are
  referred to by number only
• Rows (horizontal) Periods
• Main part vs the detached parts
• All our work will be in the main part

2
Finding Patterns in the Periodic Table

• Deal only with the main part of table
• Never bring up exceptions until a general pattern
  has been established
• Build separate Exceptions Page
• Let students discover the pattern by giving parts
  of the pattern
• Present additional required facts only as needed
  to continue story

3
 
Short Periodic Table of the Elements
1
2
13
14
15
16
17
18
1
2
1
H

He


3
4
5
6
7
8
9
10
2
Li
Be
B
C
N
O
F
Ne








11
12
13
14
15
16
17
18
3
Na
Mg
Al
Si
P
S
Cl
Ar


3
4
5
6
7
8
9
10
11
12






19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
4
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr


















37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
5
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe


















4
Starting Patterns

• No pattern

Pattern

• Symbols
• Shapes of sections
• These are called blocks (terminology later)
• There are elements that belong to groups greater
  than the number of the element!!

• Number of elements in order from left to right
• Column and Row Numbers
• Vertical in order
• Horizontal in order

5
Importance of Oxygen in Earth Chemistry

• Observations
• Oxygen most common element where we live
• There are various different highest oxides
• If oxygen were reactive it would have used up
  almost all of the other elements

• Oxygen is very reactive and will combine with
  almost all other elements
• This is what happened in the early earth (and
  most of this stuff is still around)
• O2 (found in air) was not around when the earth
  formed

Some Facts
6
Making Oxides Facts we need to know

• Atoms exist
• Compounds are made of combinations of different
  atoms
• One of the atoms will be oxygen (O) there will
  be one other element
• Compounds made of two elements are called binary
  compounds
• How to write formulas of binary compounds
• Symbol of one element with number of atoms of
  that element in the compound as a subscript
  followed by the other element with the number of
  atoms of that element as a subscript
• The number 1 is never used if there is only one
  atom of an element it is understood
• Examples CaO Sc2O3 CO2 Na2O
• Forget everything else you know!!!

7
Procedure to Use

• Partial set of facts given The highest oxides of
  some of the elements in the main part of the PT
• Water, H2O, is the most common oxide we are
  familiar with
• All oxides will be expressed as formulas of how
  many O atoms combine with 2 atoms of each element
• WARNING some formulas will not look normal from
  what you already know forget about this for now
• Exceptions will not be covered in determining the
  pattern
• Important exceptions that allow us to learn
  more will be discussed
• Other exceptions will be dealt with later
• Patterns will be determined through interactive
  class discussion

8
Periodic Table of some highest oxides of the
elements
9
Inferences Exceptions

• Pattern of number of oxygens across two parts of
  PT
• Group 1 through 7
• Group 11 through 17
• Number of oxygens in formula corresponds to the
  last digit in the group number!!
• The learning exceptions
• Group 11
• FACTS highest oxide of Ag Ag2O but of Cu
  Cu2O2
• F
• Oxide of F OF2 not F2O7 !!!!!!!!
• Something is very different in relationship of O
  to F and O to all other elements

10
Periodic Table of highest oxides of the elements
11
Electronegativity

• THE MOST IMPORTANT CONCEPT IN CHEMISTRY
• Working Definitions (Facts)
• Atoms compete for electrons (negative particles
  that surround the nucleus)
• Some atoms compete better than others because of
  how they are built (later) the more
  electronegative, the element the better it
  competes
• There is a king of the hill
• More Facts
• There is a pattern to electronegativity
• Electronegativity is quantified the larger the
  number, the more electronegative the element
• Unless the electronegativity is equal for both
  elements, in binary compounds one of the elements
  will be more electronegative than the other
• More on electronegativity later

12
Facts about formulas

• There are different kinds of formulas
• Empirical formula the lowest whole number ratio
  of atoms of each element in a substance
• Molecular Formula the actual number of atoms of
  each element in one unit of the substance
• Structural Formula an abstract picture of how
  atoms are connected in a substance
• There are different types of abstract pictures
• Only from structural formulas can we with
  certainty infer how this substance will behave
• Primary Formula Rule empirical formulas read
  from least to most electronegative element in the
  substance
• There are of course exceptions (but surprisingly
  few)

13
Reducing to Empirical Formulas

• Divide by common denominators until you cant go
  any further
• Write the formula you get
• Do not show any 1s in formula
• Examples
• C6H12O6 ? C3H6O3 ? CH2O
• P4O10 ? P2O5
• There are some species that are expressed in
  special ways because it suggests something about
  their properties
• Acids, peroxides, some salts (later as needed)

14
Final Empirical Formulas of the Highest Oxides
Making empirical formulas for oxides
CO2
BeO
MgO
SO3
SiO2
ZnO
CaO
GeO2
TiO2
SeO3
CrO3
CuO
SrO
CdO
TeO3
MoO3
SnO2
ZrO2
15
Learning More by Making Hydrides

• Binary hydrides are substances that contain
  hydrogen and one other element
• The term hydride also is the name for a certain
  class of hydrogen containing substances with a
  specific set of properties (later)
• H2O is also a hydride!
• Exercise look at an incomplete list of hydrides
  and see if we can fill in the rest by completing
  a pattern

16
Procedure to Use

• Partial set of facts given The highest hydride
  of some of the elements in the main part of the
  PT
• There are generally a limited number of hydrides
  for each element and there is only one that is
  the highest
• All hydrides will be expressed as formulas of how
  many H atoms combine with 1 atom of each element
• Exceptions will not be covered in determining the
  pattern
• Important exceptions that allow us to learn
  more will be discussed
• These include important exceptions to the primary
  formula rule
• Patterns will be determined through interactive
  class discussion

17
Partial List of Highest Hydrides
Complete List of Hydrides
H2
CH4
H F
SiH4
AlH3
PH3
H2S
H Cl
NaH
CaH2
AsH3
GaH3
H2Se
RbH
SrH2
H2Te
SnH4
H I
18
Inferences from Hydride Formulas

• Position of H vs other atom
• Recall primary formula rule
• H is more electronegative than elements through
  group 15
• H is less electronegative than elements in groups
  16 17
• There has to be an element that has an
  electronegativity equal to H
• Cant be between the columns!
• Fact P and H have the same electronegativity
• Memory device think of pH scale!
• Exceptions to formula rule
• NH3 and CH4
• Electronegativity of both N and C are greater
  than H
• How does electronegativity run?

19
Electronegativity of Main Group Elements
2.1
3.5
4.0
1.0
1.5
2.5
2.0
3.0
2.5
2.1
3.0
0.9
1.2
1.5
1.8
2.0
2.4
2.8
1.8
1.3
1.0
0.8
1.8
1.2
1.0
0.8
2.5
2.1
1.9
20
Exceptions Page

• Group 11
• highest oxide of Cu CuO (not Cu2O)
• Group 17
• Oxide of F OF2 not F2O7
• EN of FO
• Breaking the Primary formula rule
• CH4 (methane) NH3 (ammonia) both C and N are
  more electronegative than H
• All organic compounds containing C and H
• CH3 ethane
• CH2 ethylene, cyclopropane, cyclobutane
• CH acetylene, benzene, etc
• C2H3 1-butyne, cyclopropene, etc
• C2H5 butane, isobutane, etc
• And on and on!!!