[Rusky Lionheart]

Hello,

1)How can I distinguish between covalent bond and
   electrovalent bond? If I have just the molecular formula?
   Are there any rules?
                                       

2)What is pneumatic bathtub and how does it work?

Thanks,
Rusky Lionheart

[Yggdrasil]

Hello,

1)How can I distinguish between covalent bond and
   electrovalent bond? If I have just the molecular formula?
   Are there any rules?

Ionic (electrovalent) bonds are generally between a metal and a non-metal and covalent bonds are generally between two nonmetals (there are exceptions, such as in NH₄HCO₃, which is ionic; however, if you are able to recognize most of the common polyatomic ions, you will be able to recognize these exceptions).

[Rusky Lionheart]

       

Thanks a lot!