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Periodic Table of the Elements

Click an element for more information:

** Groups are noted by 3 notation conventions.
For a list of a the element names and symbols in alphabetical order, click here

Note that elements towards the left possessing a few 
electrons in higher energy orbitals tend to be 
electron donors, whereas those towards the right 
possessing nearly complete orbitals tend to be 
electron acceptors or formers of strong covalent bonds. 

    ~~~  CHARACTERISTICS OF THE PROGRESSIVE ADDITION  ~~~
           OF OXYGEN ATOMS TO THE SAME CORE ELEMENT

	increased valence/oxidation state of core element
	increased oxidant strength as electron acceptor
	increased tendency to donate oxygen atoms
	increased acidity of hydrated oxides
	some disproportionate in acid solution
	many are medicinal at low dosages
	many are toxic especially at high dosages

  ~~~  EXAMPLES OF SERIES OF COMPOUNDS HAVING THE SAME  ~~~
          CORE ELEMENT IN VARIOUS OXIDATION STATES

Chlorine:   HCl  Cl2  Cl2O  ClO2  Cl2O6  Cl2O7 
            NaClO  NaClO2  NaClO3  NaClO4 
Sulfur:     H2S  S8  SO2  H2SO3  SO3  H2SO4  H2SO5  S2O 
            H2S2O3  Na2S2O4  NaS2O5  H2S2O6  H2S2O7  H2S2O8 
Selenium:   H2Se Se  H2Se2O3  SeO2  H2SeO3  SeO3  H2SeO4 
Nitrogen:   H3N  H4N2  N2  N2O  NO  N2O3  NO2  N2O4  N2O5 
            H2N2O2  NaNO2  HNO3  HOONO 
Carbon:     H4C   C   CO   CO2 
Alkanes:    RCH3  RCH2OH  RCHO  RCO(OH)  RCO(OOH) 
Manganese:  Mn  Mn(OH)2  Mn2O3  MnO2  K2MnO4  KMnO4 
Chromium:   Cr  Cr++  Cr2O3  CrO3  K2CrO4  K2Cr2O7 
Molybdenum: Mo  MoO2  Mo2O5  MoO3  Na2MoO4 

    ~~~   DEFINITIONS  PERTAINING  TO  OXIDATION   ~~~
  oxy- or oxi- comes from the Greek word meaning to bite

	"OXIDIZE" means
	 =  to take away or remove electron(s)
	 =  to take away or remove hydrogen atom(s)
	 =  to abstract electron(s) or hydrogen atom(s)
	 =  to dehydrogenate
	 =  to increase the valence
	 =  to add atom(s) of oxygen

	"OXIDANT" means
	 =  any agent which takes away electron(s)
	 =  any agent which abstracts hydrogen atom(s)

	"OXIDATION" means
	 =  the process of removing electron(s)
	 =  the process of removing hydrogen atoms(s)

    ~~~   DEFINITIONS  PERTAINING  TO  REDUCTION   ~~~

	"REDUCE" means 
	 =  to decrease in size or volume 
	 =  to concentrate by boiling or evaporation 
	 =  to decrease the gap of a fracture 
	 =  to produce metal from ore 
It was subsequently discovered that the donation of electrons 
to ores containing cations of certain elements produced metals. 
The definition of "REDUCE" was therefore expanded to mean: 
	 =  to donate or add electron(s) or hydrogen atom(s) 
	 =  to decrease the valence 

	"REDUCTANT" means 
	 =  any agent which donates or adds electron(s) 
	 =  any agent which donates or adds hydrogen atom(s) 

	"REDUCTION" means 
	 =  the process of donating of adding electron(s) 
	 =  the process of adding hydrogen or hydrogenation 

        ~~~    DEFINITIONS  PERTAINING  TO  REDOX    ~~~

"REDOX"  is a contraction of the words reduction and oxidation.
The REDUCTANT donates electron(s) to the OXIDANT 
     which accepts them.
Such reactions are referred to as oxidation/reductions
     or "REDOX REACTIONS" for short.
The reacting donor and acceptor combination considered together
     are referred to as a "REDOX COUPLE".
Because the reductant/donor looses electrons in the process,
     it is said to be "OXIDIZED".
Because the oxidant/acceptor gains electrons in the process,
     it is said to be "REDUCED".
Thus the reductant reduces the oxidant and is oxidized,
     while the oxidant oxidizes the reductant and is reduced.

           ~~~   HALF   REACTIONS   ~~~

"HALF REACTIONS"  are a means to understand 
	and describe seperately the donating 
	and accepting aspects of redox reactions. 
The following denotes a redox reaction involving 
	the transfer of one electron: 
		D  +  A  --->  D+   +   A- 
This can be seperated into two component reactions. 
	1)    D    --->    D+    +    e- 
	2)    A    +    e-    --->    A- 
The tendency of D to denote can be measured in volts. 
The tendency of A to accept can be measured in volts. 
Such measurements for various elements and molecules 
	are published in tables.

          ~~~    REDOX   TABLES    ~~~

Redox tables list and describe numerous half-reactions. 
These are set in order according to their standard potentials. 
The hydrogen oxidation reaction is set at zero 
	for comparison purposes. 
Therefore it always appears in the middle of the table. 
Elements towards the left of the periodic table tend 
	to appear as stronger reductants in the redox tables. 
Elements towards the right of the periodic table tend 
	to appear as stronger oxidants in the redox tables. 
In most cases elements in the same column of the periodic 
	table behave as stronger oxidants as the atomic 
	number decreases. 
They behave as stronger reductants as the atomic number 
	increases. 
For most redox active agents, as the acidity level of the 
	solution increases, their strength as oxidants 
	increases. 
Elements capable of binding oxygen atoms form complexes 
	of higher oxidant strength as the valence increases. 

              ~~~   EXAMPLE  OF  REDOX  TABLE   ~~~

            ~~~    NERNST   EQUATION    ~~~
This formula predicts which direction a redox reaction 
will proceed and its electromotive force or voltage. 
                      2.303 R T        [oxidant] 
        E = E'o   +   ---------- x log----------- 
                        n F           [reductant] 

At 25 F and for 2 electron transfers this simplifies to: 
        E = E'o   +   0.03 x log [ox] / [red] 

E'o can be found in the redox tables and represents the 
actual measured voltage under standardized conditions: 
       pH = 7.0, T = 25 C, all concentrations = 1.0 M 

Note that the relative concentrations of the OXIDANTS 
and REDUCTANTS in the reaction mixture effect both the 
VOLTAGE and the direction of the reaction. 

    ~~~   EXAMPLES OF SOLUTIONS TO THE NERNST EQUATION   ~~~
What are the voltages of the half cells containing the 
following redox active agents at the concentrations given? 

1) Nicotinamide-Adenine-Dinucleotide in a two to one ratio? 
E'o = -.32	[NAD+]/[NADH] = 2	log 2 = .301 
E =  -.32 + .03 x .301  = -.32 + .009 = -.311 

2) Flavin-Mono-Nucleotide in a three to one ratio? 
E'o = -.12	[FMN]/[FMNH2] = 3	log 3 = .477 
E =  -.12 + .03 x .477  = -.12 + .014 = -.106 

3) Ubiquinone in a four to one ratio? 
E'o = +.10	[CoQ]/[CoQH2] = 4	log 4 = .602 
E =  +.10 + .03 x .602  = +.10 + .018 = +.118 

4) Cytochrome c in a ten to one ratio? 
E'o = +.24	[CytcFe+++]/[CytcFe++]=10	log 10 = 1.0 
E =  +.24 + .06 x 1.0   = +.24 + .06  = +.30 

5) Dehydroascorbic Acid and Ascorbic Acid in a one to five ratio? 
E'o = +.08	[DHAA]/[AA] = 0.2	log 0.2 = -.699 
E =  +.08 + .03x(-.699) = +.08 - .021 = +.059 

6) Lipoic Acid and Dihydrolipoic Acid in a one to eight ratio? 
E'o = -.29	[LA]/[LAH2] = 0.125	log 0.125 = -.903 
E =  -.29 + .03x(-.903) = -.29 - .027 = -.317 

Where more OXIDANT is present the voltage is more POSITIVE. 
Where more REDUCTANT is present the voltage is more NEGATIVE. 

         ~~~  OXIDOSIS   VERSUS   REDOSIS  ~~~

Numerous types and variable concentrations of oxidants 
	and reductants are present in biological fluids. 
Many of these are interactive and as a result effect 
	the overall or combined redox potential of the fluid. 
When greater than normal quantities of oxidants are present, 
	the fluid is said to be in a condition of "OXIDOSIS". 
When greater then normal quantities of reductants are present, 
	the fluid is said to be in a condition of "REDOSIS".