Network covalent atomic solids

Solids whose composite units are individual atoms are atomic solids. SoUd xenon (Xe), iron (Fe), and silicon dioxide (Si02) are examples of atomic soUds. We can classify atomic solids themselves into three categories—nonbondmg atomic solids, metallic atomic solids, and network covalent atomic solids—each held together by a different kind of force. 

Network covalent atomic solids, such as diamond, graphite, and silicon dioxide, are held together by covalent bonds. The crystal structures of these solids are more restricted by the geometrical constraints of the covalent bonds (which tend to be more directional than intermolecular forces, ionic bonds, or metallic bonds) so they do not tend to form closest-packed structures. 

Network covalent Atoms — Covalent bond Hard solids with very high melting points noncon- C... 

Network covalent Having a structure in which all the atoms in a crystal are linked by a network of covalent bonds, 240-245 properties, 245t simplest, 242 solids, 241-243 structures, 245t Neutral atoms, 28... 

SiC(s) is a network covalent solid. It contains covalent bonds between its atoms. It doesn t have any freely moving electrons or ions and so SiC doesn t conduct electricity... 

Which type of solid is solid xenon a. atomic b. molecular c. ionic d. metallic e. network covalent... 

In some solids, atoms are bonded to each other with strong covalent bonds but molecules are not formed. Instead, the covalent bonds form a network of atoms extending throughout a solid crystal. 

The atoms in network atomic solids are held together by forces created when electrons are shared between atoms. These forces create a type of chemical bond known as a covalent bond. 

Sometimes atoms or molecules can form covalent bonds with many other atoms or molecules to make huge structures that can be seen. These are called network atomic solids and can form when a covalent bond occurs between many atoms or molecules at the same time. 

The hardest network atomic solid—in fact, the hardest (currently) known material on the planet—is a type of carbon that forms diamonds. The covalently bonded arrangement of carbon atoms within diamonds forms naturally at intense temperatures and pressures inside the Earth. 

In every example seen so far the covalent bonds have held atoms together in order to make molecules. However, there exist substances such as diamond and graphite where the carbon atoms are covalently bonded but do not bond to form molecules. Such cases are called network solids the atoms bond to each other in a continuous network. The large network gives these solids a very high melting point. Also note that because both diamond and graphite are made up of the same element and are different substances, they are labeled allotropes of each other. 

Many atomic solids contain strong directional covalent bonds. We will call these substances network solids. In contrast to metals, these materials are typically brittle and do not efficiently conduct heat or electricity. To illustrate network solids, in this section we will discuss two very important elements, carbon and silicon, and some of their compounds. 

Network solid an atomic solid containing strong directional covalent bonds. (16.5)... 

Crystalline solids can be classified into five categories based on the types of particles they contain atomic solids, molecular solids, covalent network solids, ionic solids, and metallic solids. Table 13-4 summarizes the general characteristics of each category and provides examples. The only atomic solids are noble gases. Their properties reflect the weak dispersion forces between the atoms. 

Figure 9.1 4 Covalent bonds of network covalent solids. A, In quartz (Si02), eaoh Si atom is bonded covalently to four O atoms and each O atom is bonded to two Si atoms in a pattern that extends throughout the sample. Because no separate SD2 molecules are present, the melting point of quartz is very high, and it is very hard. B, In diamond, each C atom is covalently bonded to four other C atoms throughout the crystal. Diamond is the hardest natural substance known and has an extremely high melting point.

By far the most important network covalent solids are the silicates. They utilize a variety of bonding patterns, but nearly all consist of extended arrays of covalently bonded silicon and oxygen atoms. Quartz (Si02) is a common example. We ll discuss silicates, which form the structure of clays, rocks, and many minerals, when we consider the chemistry of silicon in Chapter 14. 

Physical properties reflect the change from individual molecules (N, P) to network covalent solid (As, Sb) to metal (Bi). Thus, melting points increase and then decrease. Large atomic size and low atomic mass result in low density. Because mass increases more than size down the group, the density of the elements as solids increases. The dramatic increase from P to As is due to the intervening transition elements. 

Net ionic equation an equation for a reaction in solution, where strong electrolytes are written as ions, showing only those components that are directly involved in the chemical change. (4.6) Network solid an atomic solid containing strong directional covalent bonds. (10.5)... 

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