[Jbryant3]

I am having trouble naming the rest of these compounds.  (NOTE:  I couldnt figure how to type out subscripts so bear with me)
Na2S,  PbS,  PbCl4,   (NH4)3PO3= is this ammonium phosphate???,   Hg2Cl2,   Cao.
If anyone can help me i would really appreciate it...thanks.
                                             Jami..

[Mitch]

sodium sulfide

[budullewraagh]

Na2S=Sodium Sulfide
PbS=Lead Sulfide
PbCl4=Lead Chloride
(NH4)3PO cannot be a stable compound.  the phosphorous needs to be oxidized more.  perhaps you were thinking of PO3 or PO4, which would be ammonium phosphite and ammonium phosphate respectively.
Hg2Cl2=Dimercury chloride

[AWK]

H3PO3 - it does not exists. H₃PO₃ is a dibasic acid which can exchange only two protons.
PbCl₄ - lead tetrachloride or lead(IV) chloride
Hg₂Cl₂ - dimercury dichloride or mercury(I) chloride or simply calomel
CaO - calcium oxide or lime

[jdurg]

I believe that it is incorrect to call Hg₂Cl₂ dimercury dichloride since it is an ionic compound.  The proper nomenclature would be Mercury (I) chloride, or Mercurous chloride.  While many people tend to use dimercury dichloride, it's more of a general incorrect usage.  On a standardized test, they would probably mark you wrong if you said dimercury dichloride since you are only supposed to use that method of nomenclature on covalent compounds.  (Kind of like how you wouldn't call the first compound listed "disodium sulfide".  

[Jbryant3]

thank you!!!!!!!!!!!!!!  

[budullewraagh]

actually, i thought that there was a cation called the "dimercury" ion.