what is an atomic mass unit? what are the approximate masses of the subtomic particles, expressed in atomic mass units?
1 amu is equal to one-twelfth of the mass of a carbon-12 atom, including its electrons. It is slightly less than the mass of a free neutron or a free proton.
A free electron has a mass of 1/1823 amu.
The mass of an atom is always less than the sum of the masses of its separate neutrons, protons and electrons, because the negative binding energy of the atom (which holds it together) reduces the mass.
An atomic mass unit (amu) is a unit of mass commonly used in physics and chemistry to express the relative masses of atoms and subatomic particles. It is defined as 1/12th the mass of a carbon-12 atom, which is approximately equal to the total number of protons and neutrons in the nucleus of an atom.
The subatomic particles and their approximate masses in atomic mass units are as follows:
1. Proton: A proton has a mass of approximately 1 amu.
2. Neutron: A neutron also has a mass of approximately 1 amu.
3. Electron: An electron has a much smaller mass compared to protons and neutrons. In fact, its mass is considered negligible when it comes to atomic masses. The mass of an electron is approximately 1/1836 amu, which means it is about 1/1836 times the mass of a proton or neutron.
It's important to note that although the masses of protons and neutrons are approximately 1 amu, they are not exactly equivalent. The actual masses of protons and neutrons are slightly larger than 1 amu due to additional subatomic particles like quarks, but for most practical purposes, the value of 1 amu is considered accurate.