An oxygen atom has a nucleus with protons and neutrons, and electrons that orbit around the nucleus. You can make a three-dimensional model of an oxygen atom with round objects; you can use Styrofoam balls, ping-pong balls, rubber balls or golf balls. The Periodic Table of Elements lists information about oxygen such as its atomic number and atomic mass; you will need this to figure out how many neutrons, protons and electrons are in an oxygen atom.
Search the Periodic Table of Elements to find out how many neutrons, protons and electrons an oxygen atom has. Look for diagrams of atoms to use as a reference for you model. (See the Resources section of this article.)
Draw a few large circles on the foam core to show the orbit of the electrons. To make a neat circle, tie a long piece of string to a pen. Hold the end of the string against the middle of the foam core board, which will be the center of the circle. With the string taut, draw a circle around the center.
Gather the number of balls you need for the nucleus. Use one size for the protons and one for the neutrons. Paint them, using a different color for the protons and neutrons. Glue the balls together and glue them on the foam core, in the center of the circles.
Use a marker to mark each proton with a plus sign (+) to represent a positive charge. Leave the neutrons a solid color, since they are neutral.
Gather smaller balls to make electrons. You can paint them a different color or leave them white. Glue the smaller balls against the circles you have drawn to represent electrons orbiting around the nucleus. Using a marker, draw a negative sign (-) on each electron to represent a negative charge.
Pick colors that contrast to show the different parts of the atom.