system
Given the following post, respond as if you're commenting on Reddit:
human
What happens on an atomic scale when water is boiled?

So my college entry biology professor (with a doctorate) just told my summer school class that when water boils, the hydrogen and oxygen atoms split and bind to each other, forming H2 and O2.  I have always been taught that water vapor is just water molecules that are heated to a gaseous form.

Also, if what he said is true (which at this point, I have trouble believing) than why does the ensuing H2 gas and O2 gas not react with my kitchen stove and blow my house apart when I do something like cook pasta?
gpt
Your biology professor is incorrect. There is no chemical change in the water. The H2O does not split into H2 and O2.

You have been taught correctly, that water vapor is gaseous water.

For your hypothetical, if you *did* have H2 and O2 gas, they wouldn't necessarily explode unless you have an ignition source at a temperature above the flash point (so, a gas stove). Alternately, they will spontaneously combust if they are heated above the autoignition temperature of hydrogen (~500°C).