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.
atom. 1  smallest part of an element that has all the properties of an element, (physics and chemistry) the smallest component of an element having the chemical properties of the element. 2  combining of atoms of elements to form new substances. 3  electron in the outermost energy level of an atom.