Solids can hold their shape because their molecules are tightly packed together. You might ask, "Is baby power a solid? It's soft and powdery. It's just a ground down piece of talc. Even when you grind a solid into powder, you will see tiny pieces of that solid under a microscope.
Optical Properties of Solids
Liquids will flow and fill up any shape of container. Solids like to hold their shape.
In the same way that a large solid holds its shape, the atoms inside of a solid are not allowed to move around too much. Atoms and molecules in liquids and gases are bouncing and floating around, free to move where they want. The molecules in a solid are stuck in a specific structure or arrangement of atoms.
The atoms still vibrate and the electrons fly around in their orbitals, but the entire atom will not change its position. Solid Mixtures Solids can be made of many things.
They can have pure elements or a variety of compounds inside. When you have a solid with more than one type of compound, it is called a mixture. Covalent crystals are hard, frequently brittle materials such as diamond , silicon , and silicon carbide.
In the simpler, monatomic types e. Molecular crystals are substances that have relatively weak intermolecular binding, such as Dry Ice solidified carbon dioxide , solid forms of the rare gases e. Various alloys, salts, covalent crystals, and molecular crystals that are good electrical insulators at low temperature become conductors at elevated temperatures, conductivity increasing rapidly with temperature.
THE MECHANICAL PROPERTIES OF SOLIDS | Nature
Materials of this type are called semiconductors. Their electrical conductivity is generally low when compared with that of such metals as copper, silver, or aluminum see semiconductor. Article Media. Info Print Cite. Submit Feedback.
Thank you for your feedback. See Article History. Read More on This Topic. The definition of a solid appears obvious; a solid is generally thought of as being hard and firm.
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Properties of Matter: Solids
Forgot password? Don't have an account? This chapter discusses the thermal properties of solids. When measured at constant volume where no work is done by the sample on its environment , the heat added goes directly into increasing the internal energy, E. The internal energy is computed using the methods of statistical physics; which is briefly summarized. The remainder of the chapter analyzes the equipartition law for free and bound particles; the lattice heat capacity at low temperatures or the Einstein model; and the Debye model. Sample problems are also provided at the end of the chapter.
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