Sleep Number King Size 2-3 inch Mattress Bed Foam Topper Pad 7000, i8, i9.
Quick Answer. The three parts of an atom are the protons, neutrons and electrons. Atoms make up the basic building blocks of matter and define the structure of elements. These parts were not officially identified until 1932.
General Chemistry/Atoms and Molecules - Atoms. 1  An atom is the smallest unit of matter that has the properties of an element. It is composed of a dense core called the nucleus and a series of outer shells occupied by orbiting electrons. 2  The nucleus, composed of protons and neutrons, is at the center of an atom.