ATOMS & MOLECULES

1. What is the World made up of?

The world is made up of all sorts of things. Just look around you. There are houses, cars, trees, and people. All these things are different shapes, sizes, and colors. Look closely at some of them. They are made from different materials. Some are hard and cold. Others are soft and warm. They may be wet or dry, rough or smooth. All these things look and feel different to us.

The different things in the world have two things in common. They are all made up of something, which means they have substance, and they all take up space. Anything that takes up space and has weight is called matter. So a pencil, a book, a house, a tree, the air and everything around you is matter. You are matter, too. Earth is all matter, and so are the stars through out the universe and the dust that drifts between them.



2. What is matter?

Imagine you could divide a drop of water or a grain of sand. Imagine you can divide them again and again, until the pieces are so small that you can no longer see them. Scientists can divide these tiny particles of matter even smaller under a powerful microscope. They divide them again and again, until the particles are so small that they can no longer be seen clearly, even under the microscope. Whatever in the end makes up matter is so small that we cannot see it. But everything in the world – animals, vegetables, minerals, solids, liquids, and gases – is made of matter.


Space and energy

Because space has no substance and obviously does not take up space, it does not qualify as matter. Neither does energy, which is the ability to do work.

However, matter and energy are not completely separate. Most scientists believe that matter and energy are two aspects of the same thing, like liquid water and ice are two aspects of water.

ATOMS AND MOLECULES!!!

Atoms and molecules

ATOMS AND MOLECULES!!!


Introduction
The molecular structure hypothesis - that a molecule is a collection of atoms linked by a network of bonds - was forged in the crucible of nineteenth century experimental chemistry. It has continued to serve as the principal means of ordering and classifying the observations of chemistry. The difficulty with this hypothesis was that it was not related directly to quantum mechanics, the physics which governs the motions of the nuclei and electrons that make up the atoms and the bonds. Indeed there was, and with some there still is, a prevailing opinion that these fundamental concepts, while unquestionably useful, were beyond theoretical definition. We have in chemistry an understanding based on a classification scheme that is both powerful and at the same time, because of its empirical nature, limited.
Reformulation of physics that enables one to pose and answer the questions "what is an atom in a molecule and how does one predict its properties?" These questions were posed in my laboratory where it was demonstrated that this new formulation of physics, when applied to the observed topology of the distribution of electronic charge in real space, yields a unique partitioning of some total system into a set of bounded spatial regions. The form and properties of the groups so defined faithfully recover the characteristics ascribed to the atoms and functional groups of chemistry. By establishing this association, the molecular structure hypothesis is freed from its empirical constraints and the full predictive power of quantum mechanics can be incorporated into the resulting theory - a theory of atoms in molecules and crystals.
The theory recovers the central operational concepts of the molecular structure hypothesis, that of a functional grouping of atoms with an additive and characteristic set of properties, together with a definition of the bonds that link the atoms and impart the structure. Not only does the theory thereby quantify and provide the physical understanding of the existing concepts of chemistry, it makes possible new applications of theory. These new applications will eventually enable one to perform on a computer, in a manner directly paralleling experiment, everything that can now be done in the laboratory, but more quickly and more efficiently, by linking together the functional groups of theory. These applications include the design and synthesis of new molecules and new materials with specific desirable properties.
The theory of atoms in molecules enables one to take advantage of the single most important observation of chemistry, that of a functional group with a characteristic set of properties. This document outlines and illustrates the topological basis of the theory and its relation to the quantum mechanics of an open system.

Atoms and Molecules

Welcome to the world of atoms and molecules