What differentiated these different types matter was their size, shape, and structural pattern. Robert Boyle (1627-1691) in his Skeptical Chemist (1661) proposed that all matter is composed of solid particles that can be rearranged to form new substances. A revival of atomism would have to wait until the rise of experimental science in the seventeenth century. By the Middle Ages such an explanation was rejected because it introduced the possibility that human actions were not set in motion by a divine being. Finally, if matter was made up of atoms, then a purely mechanical explanation of human actions and behavior would be possible. If matter was particulate, then there would be spaces or voids between matter, which would make motion impossible. This was in direct conflict with the idea of the four elements-earth, air, fire, and water-being the primary building blocks of everything on Earth. The concept of atoms would also mean that there were possibly an infinite number of primary substances in nature. The atomic concept was rejected by most Greek philosophers, particularly Aristotle (384-322 b.c.), because of the paradox that these atoms had no sensible properties-yet they had to be responsible for all the properties of matter that one could sense, such as an object being hot. These ideas, though interesting, could not be considered a scientific theory. The atomic theory of the Greek philosophers lacked any evidence based upon observation, measurements, and testing by experiment.
460-370 b.c.) proposed that matter was composed of individual indestructible particles (called "atoms" in Greek for "uncuttable") and that the size and shape of these particles were responsible for the properties of matter. The concept that matter may ultimately be composed of particles originated in Greek natural philosophy. The atomic theory of matter as proposed by John Dalton in his New System of Chemical Philosophy (Part I,1808 Part II,1810) was the first successful attempt to solve this problem. However, to fully understand the nature of chemical reactions one needed to have a way to visualize how the elements combined together. Was matter continuous and therefore had no finer structure or was it discontinuous and thus made of tiny particles? The chemical revolution due to the work of Antoine Lavoisier (1743-1794) and his circle that had occurred in the last two decades of the eighteenth century had clarified the concept of what elements are, developed a comprehensive and consistent vocabulary of chemistry, and led to the introduction of quantitative methods in chemical investigations. With that size, it takes over 18 million of these atoms, lined up side by side, to equal the width of your little finger (about 1 cm).John Dalton Proposes His Atomic Theory and Lays the Foundation of Modern Chemistry OverviewĪs the nineteenth century dawned a significant problem that remained in the chemical sciences was the ultimate nature of matter. Individual atoms are extremely small even the largest atom has an approximate diameter of only 5.4 × 10 −10 m. In Chapter 1 "Chemistry, Matter, and Measurement", we defined an atom as the smallest part of an element that maintains the identity of that element. The modern atomic theory The fundamental concept that all elements are composed of atoms., proposed about 1803 by the English chemist John Dalton ( Figure 2.2 "John Dalton"), is a fundamental concept that states that all elements are composed of atoms. But how far can you take this exercise, at least in theory? Can you continue cutting the aluminum foil into halves forever, making smaller and smaller pieces? Or is there some limit, some absolute smallest piece of aluminum foil? (Thought experiments like this-and the conclusions based on them-were debated as far back as the fifth century BC.) It should be obvious that the pieces are still aluminum foil they are just becoming smaller and smaller. Continue cutting, making smaller and smaller pieces of aluminum foil. Cut one of those smaller pieces in half again. Now you have two smaller pieces of aluminum foil. Explain how all matter is composed of atoms.