much larger than the nucleus because electrons expand the total size of the atom. Figure one depicts what an atom might look like structurally:
Figure 1.
So, basically, every atom has a nucleus in the center that has at least one proton in it and at least one electron, which is “orbiting” the nucleus at a fixed energy level with a certain quantum spin value. We will talk more about this quantum spin value and about “orbitals” of electrons in the next chapter. Electrons contribute much to the charge of the atom but are elementary particles of their own. As you may have surmised, an elementary particle is one that cannot be further broken down. Quarks are elementary particles, gluons are elementary particles, and the different gauge bosons (beyond the scope of this chapter) are all elementary particles, while neutrons and protons are not elementary particles.
ATOMIC NUMBER As mentioned, the atomic number is defined as the number of protons in an atom. In chemistry, it is represented by the letter Z. An element is a substance that has a specific atomic number. For example, hydrogen, the smallest element, has just one proton, having a Z value of 1. The number of protons or the atomic number defines the element. Atoms, by definition, have a neutral charge so that the number of protons is equal to the number of electrons. Carbon has six protons and six electrons, so its atomic number is
7
