Difference between revisions of "Unified Atomic Mass Units"
(Created page with "==Key Stage 5== ===Meaning=== '''Unified atomic mass units''' ('''u''' or '''Da''') is an SI unit equivalent to the mass of 1/12th the mass of a Carbon...") |
(→About Unified Atomic Mass Units) |
||
| (One intermediate revision by the same user not shown) | |||
| Line 4: | Line 4: | ||
===About Unified Atomic Mass Units=== | ===About Unified Atomic Mass Units=== | ||
| − | + | *Used to express atomic and [[Molecule|molecular]] masses. | |
| − | + | *1 u = 1.660539040 x 10<sup>-27</sup> [[Kilogram|kg]]. | |
| − | + | *Provides a convenient scale for comparing the masses of atoms. | |
| + | *'''Unified atomic mass units''' may be denoted with a lower case 'u' or with an upper case 'D', followed by a lower case 'a'. | ||
| + | *1 '''unified atomic mass unit''' is approximately equal to the [[mass]] of a free [[nucleon]] ([[proton]] or [[neutron]]). | ||
| + | *A free [[nucleon]] has a [[mass]] slightly greater than 1'''u''', but when a [[nucleon]] is bound within a [[nucleus]] some of the [[mass]] of the free [[nucleon]] has been converted into [[energy]] due to the [[Mass-Energy Equivalence|mass energy equivalence]], giving it a slightly smaller [[mass]]. | ||
| + | *Atomic and [[Molecule|molecular]] masses are often expressed in [[Unified Atomic Mass Units|atomic mass units]] to simplify calculations. | ||
| + | *The [[Unified Atomic Mass Units|atomic mass unit]] is essential for understanding stoichiometry and [[Molecule|molecular]] weight. | ||
===Examples=== | ===Examples=== | ||
Latest revision as of 10:54, 22 May 2024
Key Stage 5
Meaning
Unified atomic mass units (u or Da) is an SI unit equivalent to the mass of 1/12th the mass of a Carbon atom.
About Unified Atomic Mass Units
- Used to express atomic and molecular masses.
- 1 u = 1.660539040 x 10-27 kg.
- Provides a convenient scale for comparing the masses of atoms.
- Unified atomic mass units may be denoted with a lower case 'u' or with an upper case 'D', followed by a lower case 'a'.
- 1 unified atomic mass unit is approximately equal to the mass of a free nucleon (proton or neutron).
- A free nucleon has a mass slightly greater than 1u, but when a nucleon is bound within a nucleus some of the mass of the free nucleon has been converted into energy due to the mass energy equivalence, giving it a slightly smaller mass.
- Atomic and molecular masses are often expressed in atomic mass units to simplify calculations.
- The atomic mass unit is essential for understanding stoichiometry and molecular weight.
Examples
| Particle | Rest Mass / kg | Unified Atomic Mass Units | Rest Energy / MeV |
| Proton (\(p\)) | \(1.67\times10^{-27}\) | \(1.007\) | \(938\) |
| Neutron (\(n\)) | \(1.67\times10^{-27}\) | \(1.009\) | \(939\) |
| Electron (\(e\)) | \(9.11\times10^{-31}\) | \(0.05486\) | \(5.11\) |
| Muon (\(\mu\)) | \(1.88\times10^{-28}\) | \(0.1134\) | \(106\) |
| π-meson (\(\pi^±\)) | \(2.49\times10^{-28}\) | \(0.1500\) | \(140\) |
| π-meson (\(\pi^0\)) | \(2.41\times10^{-28}\) | \(0.1449\) | \(135\) |
| K-meson (\(K^±\)) | \(8.80\times10^{-28}\) | \(0.5300\) | \(494\) |
| K-meson (\(K^0\)) | \(8.87\times10^{-28}\) | \(0.5442\) | \(498\) |
| Photon (\(\gamma\)) | \(0\) | \(0\) | \(0\) |
| Neutrino (\(\nu\)) | \(0\) | \(0\) | \(0\) |