The structure of atoms are often compared to the planets with the nucleus of the atom at the center, much like the sun at the center of our planets. Then several electrons orbit the center, much like our planets. In Figure 2-1 we see the planetary model for the carbon atom. Our understanding of the carbon atom is very important. The carbon atom plays a critical role in the structure of plastic's atomic structure.
Carbon atoms link together to form the string-like molecule found in all plastic materials.
Electrons orbit the nucleus. The number of electrons equals the number of protons in the nucleus. The physical weight of the atoms is determined by adding the number of electrons to the number of protons. Carbon has a molecular weight of 12. Electrons have a negative charge while the protons have a positive charge.