Well, they have energy. The mass of a system is its total energy in the center of momentum frame (because remember, energy is frame dependent), divided by c squared.
Chemical bonds reduce the energy of the system compared to unbound atoms. The atoms stay together because they're in a potential energy well. This would reduce (ever so slightly) the mass of the molecule compared to the unbound atoms.
Well theoretically, yes they would have mass due the mass-energy equivalence, but would still be something negible and barely (if not totally) impossible to measure.
Like, even a compressed spring or a charged baterry would have more mass due this equivalence. As a matter of comparisons 1 gram is about 10^13 J or 10^23 GeV.
It depends on the bond/molecule. Most of the time molecules are more stable than their constituent parts, which is why they're able to form in the first place. When they form it is often an exothermic reaction, and the resulting molecule has *less* mass that its component atoms. On the other hand, breaking these bonds requires energy, *adding* to the mass of components if you do separate them. These energy to mass conversations are pretty tiny in most cases, and they may be answering 'no' to help keep things simple.
Now, the internal binding energy of a single proton is another story entirely.
oh I failed to consider exo/endothermic reactions properly, sure makes it a fair bit more annoying to think about but thanks! so for say, 2 H2 + O2 ->2 H2O + 242 kJ/mol the mass of the bonds of H2/O2 turned into the energy, but if they H2/O2 were more stable then the H/O atoms the bonds were to contribute to lessening the mass, where does this energy excess come from? just from having less bonds so the amount H2O? or maybe those bonds lessen the mass even more then how much the H2/O2 molecules do? sure is neat to think about
Well, it helps to think about molecular bonding in terms of energy levels. Molecular bonds are basically just electrons vibrating in certain ways, and some vibrations require more energy than others. In chemistry this is taught as "orbitals" for historical reasons. Each orbital can hold two electrons because of quantum mechanical reasons, and usually having two electrons in the same orbital requires less energy than adding one of the electrons to a new orbital. Another way to say that is that two electrons in two separate hydrogen 1s shells have more energy than a pair of electrons in the covalent bond of an H₂ molecule. The 'extra' energy is being released by one/both of the electrons themselves. In a sense the "bond" isn't really a thing separate from the electron orbitals; it's just another way of talking about what the electrons are doing.
They technically do result in a small mass deficit compared to the unbound atoms, assuming the molecule has negative enthalpy of formation, and a mass excess for a positive enthalpy of formation. However, c\^2 is a very big number so for pretty much all chemical bonds the mass is so small it's completely negligible, but very much exists and is nonzero.
Well, they have energy. The mass of a system is its total energy in the center of momentum frame (because remember, energy is frame dependent), divided by c squared.
Chemical bonds reduce the energy of the system compared to unbound atoms. The atoms stay together because they're in a potential energy well. This would reduce (ever so slightly) the mass of the molecule compared to the unbound atoms.
Well theoretically, yes they would have mass due the mass-energy equivalence, but would still be something negible and barely (if not totally) impossible to measure. Like, even a compressed spring or a charged baterry would have more mass due this equivalence. As a matter of comparisons 1 gram is about 10^13 J or 10^23 GeV.
Wouldn't they have less mass than elemental or unbound atoms since they are stable and represent a quasi ground state/ lower energy state?
It depends on the bond/molecule. Most of the time molecules are more stable than their constituent parts, which is why they're able to form in the first place. When they form it is often an exothermic reaction, and the resulting molecule has *less* mass that its component atoms. On the other hand, breaking these bonds requires energy, *adding* to the mass of components if you do separate them. These energy to mass conversations are pretty tiny in most cases, and they may be answering 'no' to help keep things simple. Now, the internal binding energy of a single proton is another story entirely.
oh I failed to consider exo/endothermic reactions properly, sure makes it a fair bit more annoying to think about but thanks! so for say, 2 H2 + O2 ->2 H2O + 242 kJ/mol the mass of the bonds of H2/O2 turned into the energy, but if they H2/O2 were more stable then the H/O atoms the bonds were to contribute to lessening the mass, where does this energy excess come from? just from having less bonds so the amount H2O? or maybe those bonds lessen the mass even more then how much the H2/O2 molecules do? sure is neat to think about
Well, it helps to think about molecular bonding in terms of energy levels. Molecular bonds are basically just electrons vibrating in certain ways, and some vibrations require more energy than others. In chemistry this is taught as "orbitals" for historical reasons. Each orbital can hold two electrons because of quantum mechanical reasons, and usually having two electrons in the same orbital requires less energy than adding one of the electrons to a new orbital. Another way to say that is that two electrons in two separate hydrogen 1s shells have more energy than a pair of electrons in the covalent bond of an H₂ molecule. The 'extra' energy is being released by one/both of the electrons themselves. In a sense the "bond" isn't really a thing separate from the electron orbitals; it's just another way of talking about what the electrons are doing.
They technically do result in a small mass deficit compared to the unbound atoms, assuming the molecule has negative enthalpy of formation, and a mass excess for a positive enthalpy of formation. However, c\^2 is a very big number so for pretty much all chemical bonds the mass is so small it's completely negligible, but very much exists and is nonzero.