Explain why electrons are described as 'lightweight particles that orbit the nucleus'.

Electrons are described as 'lightweight' because their mass is significantly smaller than that of protons and neutrons. They 'orbit the nucleus' because they are found in a cloud-like region around the central nucleus, attracted by the positive charge of the protons.
The mass of an electron is approximately 1/1836th the mass of a proton. Their motion around the nucleus is often described as 'orbiting' or existing in 'electron shells' or 'orbitals,' driven by the electrostatic attraction to the positively charged nucleus.