# Why are all of the group 16 hydrides/hydrogen chalcogenides except H2O toxic? [closed]

I mean ($$\ce{H2O}$$) is non-toxic and is needed everyday but all of the other group 16 hydrides (hydrogen sulfide ($$\ce{H2S}$$), hydrogen selenide ($$\ce{H2Se}$$), hydrogen telluride ($$\ce{H2Te}$$) and hydrogen polonide or polonium hydride ($$\ce{H2Po}$$) are toxic and flammable. We observe that water is an outlier. Why is this the case?

• Because life was born in an ocean of water. Apr 29 '21 at 0:25
• It is just confusing because you would think since a chemical is related to one of the other you would think that it is similar,but chemistry is obviously more complicated then that Apr 29 '21 at 2:14
• chemistry.stackexchange.com/questions/86540/… Apr 29 '21 at 14:18
• Chemistry within a group is not as similar as the Periodic Table might lead one to believe (except, perhaps, in groups 1 and 2). You should already know that first-row elements (B, C, N, O, F) stand out in terms of e.g. hydrogen bonding. I'm not trying to say that toxicity is caused by the lack of hydrogen bonding, I'm just trying to point out that there are substantial differences between O and S (and beyond), and perhaps it's not all that surprising after all. Apr 29 '21 at 23:33
• Continuing Mithoron's comment: H2O is liquid others are gas. So, how do they contribute to toxicity? Because of its volatility and smell. Due to them being gas, they have the tendency to have higher exposure to human body than water, so they are more prone to be to smelly and toxic. See: chemistry.stackexchange.com/questions/81935/… Jun 24 '21 at 8:04