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.
The number of electrons determine the size of the atom. The electrons, depending upon their number, divide themselves in seven levels from the center of the atom. The division is a direct result of their negative charge. The smaller orbits hold fewer electrons than the larger orbits. Thus the farther away from the nucleus, the more electrons in the orbits.