OBJECTIVE: To describe Rutherford’s model of the atom.
Remember that in Chapter 4 we discussed the idea that an atom has a small positive core (called the nucleus) with negatively charged electrons moving around the nucleus in some way (Figure 11.1). This concept of a nuclear atom resulted from Ernest Rutherford’s (see Section 4.5). Rutherford and his coworkers were able to show that the nucleus of the atom is composed of positively charged par- ticles called protons and neutral particles called neutrons. Rutherford also found that the nucleus is apparently very small compared to the size of the entire atom. The electrons account for the rest of the atom.
A major question left unanswered by Rutherford’s work was, What are the electrons doing? That is, how are the electrons arranged and how do they move? Rutherford suggested that electrons might revolve around the nucleus like the planets revolve around the sun in our solar system. He couldn’t explain, however, why the negative electrons aren’t attracted into the positive nucleus, causing the atom to collapse.
At this point it became clear that more observations of the properties of atoms were needed to understand the structure of the atom more fully.