By Amy Shelleby
Updated Mar 24, 2022
All atoms consist of a nucleus—composed of protons and neutrons—and surrounding electrons that occupy discrete energy shells. To construct a realistic model of a potassium atom, you’ll need to know the exact numbers of each subatomic particle.
Consult a periodic table that lists both atomic number and atomic weight (e.g., the Commission on the Nomenclature of Inorganic Chemistry’s table). Potassium (K) has an atomic number of 19, meaning it contains 19 protons and, in a neutral atom, 19 electrons. Subtract the atomic number from the atomic weight (approximately 39.0983) to find the neutron count: 39 – 19 = 20 neutrons.
Glue 19 red hard‑shelled candies onto a 4‑inch Styrofoam ball to represent the 19 protons. Then glue 20 blue hard‑shelled candies onto the same ball for the neutrons.
Thread an 18‑inch piece of craft wire through two 1‑inch Styrofoam balls. Bend the wire into a circle and twist the ends together. These two balls represent the two electrons in the first shell.
Use a 24‑inch wire segment and eight 1‑inch Styrofoam balls. Form a circle with the wire and arrange the eight balls evenly around it to model the eight electrons in the second shell.
Thread eight 1‑inch Styrofoam balls through a 30‑inch wire piece, twist the ends, and circle the balls to depict the third shell’s eight electrons.
Insert a single 1‑inch Styrofoam ball into a 36‑inch wire segment, twist the ends into a circle, and leave it open to illustrate potassium’s solitary valence electron. This incomplete shell accounts for the element’s +1 charge.
Bend a 4‑inch wire into a U‑shape. Place the open end of the U inside the 4‑inch Styrofoam nucleus, leaving a ½‑inch loop protruding.
Position the shells in order of increasing distance: the two‑electron shell nearest the nucleus, followed by the two eight‑electron shells, and finally the single‑electron shell farthest away.
Cut a fishing line 12 inches longer than the total span from nucleus to the outermost shell. Thread it through the U‑shaped wire loop, pull it to the next shell, and double‑knot it. Repeat this process for each shell, tying the entire model together. The remaining fishing line can attach the atom to a hook for display.
Construct a large, hands‑on model of a potassium atom using Styrofoam, candies, and craft wire to represent the nucleus and electron shells. A smaller version can be made with a single Styrofoam ball for the nucleus and shorter wire pieces with jelly beans or cotton balls for electrons.
