The Particulate Nature of Matter

Matter, the stuff of which the universe is composed, has two characteristics it has mass and it occupies space. Matter comes in a great variety of forms the stars, the air that you are breathing, the gasoline that you put in your car, the chair on which you are sitting, the turkey in the sandwich you may have eaten for lunch, the tissues in your brain that allow you to read and understand this sentence, and so on. 

As we look around our world, we are impressed by the great diversity of matter. Given the many forms and types of matter, it seems difficult to believe that all matter is composed of a small number of fundamental particles. It is surprising that the fundamental building blocks in chocolate cake are very similar to the components of air. 

How do we know that matter is composed of the tiny particles we call atoms After all, they are far too small to be seen with the naked eye. It turns out that after literally thousands of years of speculation, we can finally see the atoms that are present in matter. In recent years scientists have developed a device called a scanning tunneling microscope (STM) that, although it works quite differently from an optical microscope, can produce images of atoms. 

With ultra-high magnification, objects appear more similar. All objects 

All matter consists of tiny particles called atoms. But when you look at objects such as nails or pennies, you don t see these particles. Why not  

We study many theories and laws in chemistry this makes our task as students easier because theories and laws summarize important aspects of the sciences. Certain theories and models advanced by great scientists in the past have since been substantially altered and modified. Such changes do not mean that the discoveries of the past are any less significant. Modification of existing theories and models in the light of new experimental evidence is essential to the growth and evolution of scientific knowledge. Science is dynamic. 

The entire universe consists of matter and energy. Every day we come into contact with countless kinds of matter. Air, food, water, rocks, soil, glass, and this book are all different types of matter. Broadly defined, matter is anything that has mass and occupies space. 

Matter may be quite invisible. For example, if an apparently empty test tube is submerged mouth downward in a beaker of water, the water rises only slightly into the tube. The water cannot rise further because the tube is filled with invisible matter air 

An apparently empty test tube is submerged, mouth downward, in water. Only a small volume of water rises into the tube, which is actually filled with invisible matter—air. 

Xenon atoms on a nickel surface produced this image made visible by using a scanning tunneling microscope. 

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For example, the measured pressure exerted by an enclosed gas can be thought of as a time-averaged manifestation of the individual molecules random motions. When one considers an individual molecule, however, statistical thermodynamics would propose its random motion or pressure could be quite different from that measured by even the most sensitive gauge which acts to average a distribution of individual molecule pressures. The particulate nature of matter is fundamental to statistical thermodynamics as opposed to classical thermodynamics, which assumes matter is continuous. Further, these elementary particles and their complex substmctures exhibit wave properties even though intra- and interparticle energy transfers are quantized, ie, not continuous. Statistical thermodynamics holds that the impression of continuity of properties, and even the soHdity of matter is an effect of scale. 

Harrison, A. G., Treagust, D. F. (2002). The particulate nature of matter Challenges to understanding the submicroscopic world. In J. Gilbert, K., O. de Jong, R. Justi, D. F. Treagust J. H. Van Driel (Eds.), Chemical education Towards research-based practice (pp. 189-212). Dordrecht Kluwer. 

Novick, S., Nussbaum, J. (1978). Junior high school pupils understanding of the particulate nature of matter An interview study. Science Education, 62(3), 273-281. 

Brook, A., Briggs, H., Driver, R. (1984). Aspects of secondary students understanding of the particulate nature of matter. University of Leeds Centre for Studies in Science and Mathematics Education. 

Haidar, A., Abraham, M. (1991). A comparison of applied and theoretical knowledge of concepts based on the particulate nature of matter. Journal of Research in Science Teaching, 28, 919-938. 

Having students draw their mental model of the product of the reaction reveals misconceptions in understanding of the particulate nature of matter which could then be addressed in the classroom. 

Despite this much-discussed theoretical background, the number of concrete studies comparing historical ideas and students conceptions is fairly low in chemistiy education. Furthermore, most studies cited deal with isolated topics. Systematic overviews concerning basic ideas like micro-macro thinking, chemical reaction, the particulate nature of matter, energy conversions etc. are mostly not available, except for van Driel et al. (1998) and the case of the chemical equilibrium. 

Ozmen (2004, especially for chemical bonding) and Coll und Treagust (2003, chemistiy of metals) can help to develop a first overview. Numerous authors (e g. Pfund, 1975 Schldpke, 1991 Griffith and Preston, 1992 Mas et al., 1987) describe parallels between students conceptions and historical scientific ideas. Schldpke (1991), for example, points out similarities between students conceptions concerning properties of matter and ideas in alchemist thinking. Lee, Eichinger, Anderson, Berkheimer, and Blakeslee (1993) mentions semblances between the ideas of Aristotle and students conceptions about general aspects of the particulate nature of matter and the horror vacui . 

Gabel, D. (1993). Use of the particulate nature of matter in developing conceptual understanding. Journal of Chemical Education, 70(3), 193-197. 

One property that remains in the current concept of atom is discreteness. If anything, evidence for the particulate nature of matter has continued to accumulate over that time, notwithstanding the fact that particles can display wavelike phenomena such as diffraction and regardless of their ultimate nature (quarks multidimensional strings something else ). 

However, J. J. Thomson did not irrefutably establish the particulate nature of matter. It remained until 1909 for Jean Perrin to provide the definitive evidence for atoms, which he did by measuring the motion of microscopic pollen particles suspended in water. His detailed observations of this Brownian motion (named after the botanist Robert Brown) could be explained if it were assumed they were being buffeted about by moving atoms. His observations convinced the scientific community of the validity of the atomic model. Of course, they had been using the... 

Gabel DL, Samuel KV, Hunn D (1987) Understanding the particulate nature of matter. J Chem Educ 64 695-697... 

Gabel, D.L., Samuel, K.V., Hunn, D. Understading the particulate nature of matter. Journal of Chemical Education 64 (1987), 695... 

Continuum models are used almost exclusively in this book and are adequate down to the microscale. They fail on the nanoscale where it becomes necessary to directly address the particulate nature of matter. On the nanoscale, the diffusion times and Reynolds numbers shown in Table 16.1 become rather meaningless. Instead, the models must address the behavior of individual molecules. Thus, an alternative definition of the nanoscale is the scale at which continuum models must be replaced by molecular models. 

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