Final answer:
The three subatomic particles are protons (positive charge, 1 amu, located in the nucleus), neutrons (no charge, 1 amu, in the nucleus), and electrons (negative charge, 1/2000 amu, orbiting in shells around the nucleus). An atomic mass unit (amu) is defined based on the mass of a carbon-12 atom.
Step-by-step explanation:
Basic Features of Subatomic Particles
Atoms are known to be composed of three main subatomic particles: protons, neutrons, and electrons. Each of these particles has unique properties, including symbol, relative mass, charge, and location within the atom.
- Protons (symbol p or p+) have a positive charge and a relative atomic mass of approximately 1 atomic mass unit (amu). They are located in the atom's nucleus.
- Neutrons (symbol n or n0) have no charge (neutral) and a relative atomic mass close to 1 amu, similar to that of a proton. Neutrons are also located in the nucleus of the atom.
- Electrons (symbol e) have a negative charge and a much smaller relative mass of about 1/2000 amu. Electrons orbit the nucleus in various energy levels (shells).
An atomic mass unit (amu) is defined as one-twelfth of the mass of a carbon-12 atom. This unit is used because the masses of protons and neutrons are nearly identical and close to 1 amu, making it a convenient reference point for measuring atomic mass.