5 ms·
Apparently picograms are still orders of magnitude bigger and thus not useful for this type of measurement. Science! Looking further into it, yoctagrams or zet
by b34r 6y ago
Apparently picograms are still orders of magnitude bigger and thus not useful for this type of measurement. Science!
Looking further into it, yoctagrams or zetograms would be small enough to express the measurement. I suspect daltons are used because they’re pegged to a 1/12 of a carbon atom and that makes the math easier to reason about or something like that.
- deleted 6y ago[deleted]
- dmurray 6y agoYeah, one Dalton = one neutron or one proton [0], so it's a convenient unit if you're literally adding up atomic weights to find the weight of a single molecule. [0] This is true for chemists, but not for physicists, who pay more attention to the mass defect rounding error.
- contravariant 6y agoTo expand on that, for physicists Carbon-12 is exactly 12 daltons also denoted 12 Da or 12 u. All other isotopes deviate slightly from a whole number of daltons. If I recall correctly the number of nucleons minus the daltons continues to decrease until you get to iron, which has the lowest nuclear binding energy, after which it continues to increase again (although there's some variation between isotopes so this is more of a general trend).
- dmurray 6y agoAnd that's why you can have nuclear power either from combining really small atoms (fusion) or splitting big ones (fission) but nobody would propose a nuclear reactor that runs on iron?
- zokier 6y ago1 Da = 1.66 yg (yoctograms), approximately. So that kinda works out. Another unit that is occasionally used for atomic scale masses is eV, as in electronvolt. 1 Da = 0.93 GeV
- b34r 6y agozeptograms