PS & acid-base

How the acid base character is connected to the position in the Periodic Table
Study well this periodic tabel and lets have a special look at some periods.
(the noble gase are left out; they do not form any bondings, also no acids or bases)

I.


Period 2,
Li - F
Compounds with Hydrogen (hydrides)
LiH       BeH2       BH3       {CH4}         NH3         H2O         HF
Strong Base ---------------------weak base - neutral - weak acid
From left to right we see a gradual transition from base to acid,
where water is a real neutral substance, also CH4 for other reasons than water.
The Hydride ion (H-) is is very basic and can be donated by LiH and BeH2.
BH3 and NH3 have the tendency to catch H+,
so they are weak basic, where NH3 is weaker than BH3.
Compounds with Hydrogen and Oxygen
LiOH     Be(OH)2     B(OH)3 = H3BO3     H2CO3 (=H4CO4)     HNO3     [H2O]     HFO3
Base ---------------------------amphoteric ----------- weak acid -------- strong acid
From left to right again you have a change from basic to acid,
where water also is a substance with Hydrogen and Oxygen,
but that remains out of this analysis.
The element B, connected with Oxygen and Hydrogen,
can become Borium hydroxyde or Boric acid (can donate one H).
Those two are similar.
This substance we call an amphoteric substance or an ampholyte.
II.


Period 3,
Na - Cl
Compounds with Hydrogen (hydrides)
NaH     MgH2     AlH3     {SiH4}       PH3       H2S       HCl
strong base --------------- weak base - weak acid - strong acid
From left to right we see a change from basic to acid,
with SH4 neutral for several reasons.
The ion H- is very basic and can be donated by LiH and BeH2.
BH3 and NH3 do have the tendency to catch protons,
where NH3 is weaker than BH3.
Compounds with Hydrogen and oxygen
NaOH Mg(OH)2 Al(OH)3=H3AlO3=HAlO2 H4SiO4=H2SiO3 H3PO4 H2SO4 HClO3
Base ---------------- amphoteric ------------ weak acid --------- strong acid
From left to right we see change from basic to acid.
The element Al, connected to Oxygen and Hydrogen,
can deliver an amphoteric substance.
III.


Group 1,
Li Cs
Compounds with Hydrogen (hydrides)
LiH - NaH - KH - RbH - CsH (all are hydrides)
Base --------------------- very strong base
The ion H- is an ion with a very strong basic character.
Compounds with Hydrogen and Oxygen
LiOH       NaOH       KOH       RbOH       CsOH
Base --------------------------- very strong base
All are strong bases because of the presence of the ion OH-
All are ionic bonds.
The ion rays of the positive ions increase from top to bottom.
IV.


Group 5,
N - Bi
Compounds with Hydrogen (hydrides)
NH3     PH3     AsH3     SbH3     BiH3 (All are hydrides)
weak base --------------------- strong base
The ion H- is an ion with a very strong basic character
Compounds with Hydrogen and Oxygen
HNO3       H3PO4       H3AsO4       H3SbO4       H3BiO4
strong acid --- weaker acid --- amphoteric --- weak base
From top to bottom these substances lose their acid character
V.


Group 6
O - Po
Compounds with Hydrogen (hydrides)
H2O       H2S       H2Se       H2Te       H2Po
amphoteric ----- weak acid -------- strong acid
The ion H- is an ion with a very strong basic character
Compounds with Hydrogen and Oxygen
H2O     H2SO4    H2SeO4     H2TeO4     H2PoO4
amphoteric---- strong acid ------ weaker acids
VI.


Group 7,
F - At
Compounds with Hydrogen (hydrides)
HF     HCl     HBr     HI     HAt
weak acid ------- strong acids
Compounds with Hydrogen and Oxygen
(HFO3)            HClO3     HBrO3     HIO3     HAtO3
Does not exist     strong acid ------- weaker acids
    Of the compounds of the elements with Hydrogen and Oxygen, the acid and basic properties do change within the Periodic Table:
  • in the Periods: from left to right, from basic to acid
  • in the Groups: from top to bottom, from basic to acid
    In the Periodic Table the acid base character of substances with Hydrogen will shift
  • In the periods: from left to right: from basic to acid
  • In the groups: from top to bottom: from basic to acid

 B : basic character
 A : acid character
 O : amphoteric character
  xxx           strong acids
      xxx                      
          xxx                  
              xxx              
                  xxx          
strong bases      xxx    
compounds with H and O
  B     B     B           B     O     A  
  B     B     B     O     A     A     A  
  B     B     B     O     O     A     A  
  B     B     B     B     O     A     A  
  B     B     B     B     B     O     A  
  B     B             A  
             
strong bases                 xxx  
                      xxx      
                  xxx          
              xxx              
          xxx                  
      xxx       strong acids
compounds with H
  B     B     B         B     O     A  
  B     B     B      O     B     A     A  
  B     B     B       A     A     A  
  B     B     B       A     A     A  
  B     B     B       A     A     A  
  B     B             A