Mosquitoes, common smaller species (about 2.5 milligrams), grain of salt or sand, medicines are typically expressed in milligrams Uncertainty in the mass of the International Prototype of the Kilogram (IPK) (±~20 μg) Speculated approximate lower limit of the mass of a primordial black hole Very fine grain of sand (0.063 mm diameter, 350 nanograms) Prochlorococcus cyanobacteria, the smallest (and possibly most plentiful) photosynthetic organism on Earth ĭNA in a typical diploid human cell (approximate)ĭunaliella salina, a green alga (dry weight) ġ0 −12 to 10 −6 kg Scanning electron micrograph showing grains of sand Nuclear pore complex in yeast (66 MDa) ĭNA sequence of length 4.6 Mbp, the weight of the E. Synaptic vesicle in rats (16.1 ± 3.8 MDa) Haemoglobin A molecule in blood (64.5 kDa) ĭouble-stranded DNA molecule consisting of 1,578 base pairs (995 kDa) īrome mosaic virus, a small virus (4.6 MDa) Ubiquitin, a small protein (8.6 kDa) Ī typical protein (median size of roughly 300 amino acids ≈ 33 kDa) Oganesson-294 atom, the heaviest known nuclideġ0 −24 to 10 −18 kg Factor ( kg) Top quark (173 GeV/ c 2), the heaviest known elementary particle Up quark ( as a current quark) (1.7–3.1 MeV/ c 2) ĭalton (Da), a.k.a. Mass equivalent of the energy of a photon at the peak of the spectrum of the cosmic microwave background radiation (0.235 meV/ c 2) ġ eV/ c 2, the mass equivalent of one electronvolt Įlectron neutrino, upper limit on mass (2 eV/ c 2) Įlectron (511 keV/ c 2), the lightest elementary particle with a measured nonzero rest mass Graviton, upper bound (4.7 ×10 −23 eV/ c 2) Consequently, there can only ever be an experimental upper bound on the mass of a supposedly massless particle in the case of the photon, this confirmed upper bound is of the order of 3 ×10 −27 eV/ c 2 = 10 −62 kg. Planck's law allows for the existence of photons with arbitrarily low energies. Unlike other physical quantities, mass–energy does not have an a priori expected minimal quantity, or an observed basic quantum as in the case of electric charge. The least massive things: below 10 −24 kg Astronomers use the mass of the sun ( M ☉). At the atomic level, chemists use the mass of one-twelfth of a carbon-12 atom (the dalton). Historical units include the stone, the pound, the carat, and the grain.įor subatomic particles, physicists use the mass equivalent to the energy represented by an electronvolt (eV). For example, a gigagram ( Gg) or 10 9 g is 10 3 tonnes, commonly called a kilotonne. The unit is in common use for masses above about 10 3 kg and is often used with SI prefixes. The tonne (t) is an SI-compatible unit of mass equal to a megagram ( Mg), or 10 3 kg. However, the names of all SI mass units are based on gram, rather than on kilogram thus 10 3 kg is a megagram (10 6 g), not a * kilokilogram. The gram (10 −3 kg) is an SI derived unit of mass. The kilogram is the only standard unit to include an SI prefix ( kilo-) as part of its name. The table at right is based on the kilogram (kg), the base unit of mass in the International System of Units ( SI).
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