No, an electron is not massless. It has a very small but definite mass.
While often considered "nearly massless" when compared to protons and neutrons, electrons possess a non-zero rest mass. This mass is a fundamental property of the electron and is crucial to many physical phenomena.
Here's a breakdown:
- Electron Mass: The rest mass of an electron is approximately 9.1093837015 × 10−31 kg.
- Comparison to Protons and Neutrons: This is only about 1/1836 the mass of a proton. Due to this significant difference, the electron's mass is often disregarded when calculating the mass number of an atom.
- Why it Matters: Even though it's small, the electron's mass is vital in determining the behavior of atoms and molecules. It affects things like chemical bonding, electrical conductivity, and many other properties of matter. Without mass, electrons wouldn't interact with gravitational fields or possess momentum in the same way.
In summary, although tiny, the electron has a measurable mass and is therefore not massless. The statement regarding 'nearly massless' is merely a comparison to the much larger proton or neutron.
