Dehydration Synthesis: Why does a monomer contribute a -H instead of an H atom? My Campbell's Biology 9th edition textbook says that a dehydration synthesis is a reaction in which water is produced while two monomers are joined together. Specifically, it makes the following statement: > One monomer provides a hydroxyl group (-OH), while the other provides a hydrogen (-H). Sorry if this is a silly question to ask, but what I'm wondering is how exactly a Hydrogen electron joined with a Hydroxyl will create H2O? Why isn't it a Hydrogen atom (1 proton and 1 electron) rather than just the electron which moves?

The dash ("-") does not represent a negative charge or an electron. It simply indicates that the group of atoms ( -OH or -H ) are attached (covalently bonded) to other atoms in a molecule. So they are saying one monomer (molecule) contributes OH to the reaction and the other H. (A charge is indicated by a trailing superscript minus sign.)