The electron is the lightest particle in the atom.
No. The two phrases have almost nothing to do with each other at all.
The electron has the smallest mass between subatomic particles: 9,10938291(40).10-31 kg.
Subatomic particles with no mass are called neutrinos. Neutrinos are elementary particles that have extremely small, non-zero masses, but they are considered nearly massless in many calculations due to their very small mass values.
Subatomic particles have mass, dimensions, spin, sometimes have an electrical charge.
Electrons are negatively charged subatomic particles, but have almost no mass. The mass of an electron is about 1/2000 that of a proton or neutron. The neutron is the most massive of the subatomic particles at 1.6755 x 10-24 grams.
Negatively charged particles with almost no mass are called electrons. These subatomic particles orbit around the nucleus of an atom and are responsible for carrying electrical current and facilitating chemical reactions.
Neutrons have almost the same mass as protons. They are both subatomic particles found in the nucleus of an atom and are collectively referred to as nucleons. The mass of a neutron is only slightly greater than that of a proton.
"All subatomic particles have the same mass" is not a true statement, as different subatomic particles, such as protons, neutrons, and electrons, have different masses and charges.
The neutron is the subatomic particle that has appreciable mass and lacks a charge.
neutrons and protons
I think you probably mean the mass of the classical subatomic particles, Proton, Neutron and Electron. From memory, the mass of the proton and neutron are almost the same and approximately 1.6 x 10-24 grams while the mass of an electron is about 0.9 x 10-28 grams. In the Standard Model of subatomic particles, there are very many more particles than these three and their masses are best looked up in tables. Some of the masses of subatomic particles have not yet been determined (neutrinos) and one of the theoretical particles has not yet been shown to exist at this time (Higgs boson).
protons and neutrons are subatomic particles and adding the two amounts together gives you the atomic mass unit