7: Solids and Liquids
The pages present an overview of the condensed states of matter. Although there is more detail than can be found in standard textbooks, the level is still suitable for first-year college and advanced high school courses. These pages should also be helpful as review material for students in more advanced courses in chemistry, geology, and materials science.
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- 7.1: Matter under the Microscope
- Gases, liquids, and especially solids surround us and give form to our world. Chemistry at its most fundamental level is about atoms and the forces that act between them to form larger structural units. But the matter that we experience with our senses is far removed from this level. This unit will help you see how these macroscopic properties of matter depend on the microscopic particles of which it is composed.
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- 7.2: Intermolecular Interactions
- Liquids and solids differ from gases in that they are held together by forces that act between the individual molecular units of which they are composed. In this lesson we will take a closer look at these forces so that you can more easily understand, and in many cases predict, the diverse physical properties of the many kinds of solids and liquids we encounter in the world.
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- 7.4: Liquids and their Interfaces
- The molecular units of a liquid, like those of solids, are in direct contact, but never for any length of time and in the same locations. Rapid chemical change requires intimate contact between the agents undergoing reaction, but these agents, along with the reaction products, must be free to move away to allow new contacts and further reaction to take place. This is why so much of what we do with chemistry takes place in the liquid phase.
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- 7.5: Changes of State
- A given substance will exist in the form of a solid, liquid, or gas, depending on the temperature and pressure. In this unit, we will learn what common factors govern the preferred state of matter under a particular set of conditions, and we will examine the way in which one phase gives way to another when these conditions change.
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- 7.6: Introduction to Crystals
- Crystallography is of importance not only to chemists and physicists, but also to geologists, amateur minerologists and "rock-hounds". In this lesson we will see how the external shape of a crystal can reveal much about the underlying arrangement of its constituent atoms, ions, or molecules.In this lesson we will see how the external shape of a crystal can reveal much about the underlying arrangement of its constituent atoms, ions, or molecules.
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- 7.7: Ionic and Ion-Derived Solids
- In this section we deal mainly with a very small but imporant class of solids that are commonly regarded as composed of ions. We will see how the relative sizes of the ions determine the energetics of such compounds. And finally, we will point out that not all solids that are formally derived from ions can really be considered "ionic" at all.
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- 7.8: Cubic Lattices and Close Packing
- When substances form solids, they tend to pack together to form ordered arrays of atoms, ions, or molecules that we call crystals. Why does this order arise, and what kinds of arrangements are possible? We will limit our discussion to cubic crystals, which form the simplest and most symmetric of all the lattice types. Cubic lattices are also very common — they are formed by many metallic crystals, and also by most of the alkali halides, several of which we will study as examples.
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- 7.9: Polymers and Plastics
- Synthetic polymers, which includes the large group known as plastics, came into prominence in the early twentieth century. Chemists' ability to engineer them to yield a desired set of properties (strength, stiffness, density, heat resistance, electrical conductivity) has greatly expanded the many roles they play in the modern industrial economy. This Module deals mostly with synthetic polymers, but will include a synopsis of some of the more important natural polymers.
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- 7.10: Colloids and their Uses
- Colloids occupy an intermediate place between [particulate] suspensions and solutions, both in terms of their observable properties and particle size. In a sense, they bridge the microscopic and the macroscopic. As such, they possess some of the properties of both, which makes colloidal matter highly adaptable to specific uses and functions. Colloid science is central to biology, food science and numerous consumer products.