Lesson 2 Matter

Early scientists or philosophers such as Democritus, Aristotle, and Socrates developed theories based on hypothesizing instead of experimenting. With the development of the scientific method, evidence-based theories became the standard for science. The following pages highlight some of the key historical developments in atomic theory. Each scientist built upon the knowledge of the previous model, and through collaboration, scientists have modified historical theories into a unifying atomic theory (known as the quantum mechanical model of the atom). But scientists are not done; even this model is still being modified, as better equipment, mathematical models, and scientific understanding arise.