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.
Structure of a beryllium atom: four protons, four neutrons and four electrons. Atoms are the basic units of matter and the defining structure of elements. The term atom comes from the Greek word for indivisible, because it was once thought that atoms were the smallest things in the universe and could not be divided.