Determine which element you will be modeling. The periodic table shows all the atoms, their atomic number -- number of protons -- and their atomic weight. The numbers of protons and electrons are the same in each atom of a particular element. Carbon, for example, has the atomic number of 6, meaning there are 6 protons and 6 electrons in one carbon atom. It has the atomic weight of 12.017. This weight is rounded to the nearest whole number; because protons are located in the nucleus with the neutrons, subtract the number of protons from the atomic weight. Carbon's atomic weight is 12 and it has 6 protons; carbon's number of neutrons is also 6.
Create protons, neutrons and electrons. Ball up several strips of newspaper. Wad them tightly. Mix 1/2 cup of glue with 1/2 cup of warm water. Dip strips of colored paper in the glue solution and wrap them tightly around the balls. Protons, neutrons and electrons should all be different colors so they can be distinguished from each other in the model. Let them dry thoroughly. Wrap strips of the fourth color of paper around enough drinking straws to hold each electron. Let them dry.
Arrange the protons and neutrons in a nucleus. Carbon would have 12 balls in the center -- 6 protons and 6 neutrons. Glue these in place and set them aside. Glue drinking straws to the electrons with undiluted glue. Let them dry for a few moments to allow the glue to hold. The time will vary depending on the conditions of the air and strength of the glue. Glue the other end of the straws to the nucleus. Let the model air-dry thoroughly. Tie the yarn or fishing wire around part of the model to hang it.