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Chapter 12: Problem 66

Which of the following properties are typical characteristics of a covalent- network solid, a metallic solid, or both: (a) ductility, (b) hardness, (c) high melting point?

Short Answer

Expert verified
Ductility is a typical characteristic of metallic solids. Hardness and high melting points are typical characteristics of both covalent-network solids and metallic solids.

Step by step solution

01

Property (a): Ductility

Ductility is the ability of a material to deform or stretch under tensile stress without breaking. Since metallic solids have delocalized electrons, they can easily slide past each other without breaking the bonds. Therefore, ductility is a characteristic of a metallic solid. Covalent-network solids are generally brittle due to their strong, directional covalent bonds; hence, they are not ductile.
02

Property (b): Hardness

Hardness refers to the resistance of a material to localized deformation, such as indentation or scratching. Due to the strong covalent bonds present in covalent-network solids, they exhibit high hardness. In general, metallic solids are softer than covalent-network solids, but some metallic solids exhibit hardness as well, such as tungsten and steel. So, hardness can be a characteristic of both covalent-network solids and some metallic solids.
03

Property (c): High Melting Point

The melting point refers to the temperature at which a substance changes from a solid to a liquid. A high melting point indicates strong bonds between the atoms or ions. Covalent-network solids have strong directional covalent bonds, which results in high melting points. Metallic solids have metallic bonds involving the delocalization of electrons and also exhibit high melting points. Therefore, a high melting point is a characteristic of both covalent-network solids and metallic solids. In summary: - Ductility: typical characteristic of a metallic solid. - Hardness: typical characteristic of both a covalent-network solid and some metallic solids. - High melting point: typical characteristic of both covalent-network solids and metallic solids.

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Most popular questions from this chapter

Sodium metal (atomic weight \(22.99 \mathrm{~g} / \mathrm{mol}\) ) adopts a bodycentered cubic structure with a density of \(0.97 \mathrm{~g} / \mathrm{cm}^{3}\). (a) Use this information and Avogadro's number \(\left(N_{A}=6.022 \times 10^{23} / \mathrm{mol}\right)\) to estimate the atomic radius of sodium. (b) If sodium didn't react so vigorously, it could float on water. Use the answer from part (a) to estimate the density of Na if its structure were that of a cubic close-packed metal. Would it still float on water?

Which of the following statements does not follow from the fact that the alkali metals have relatively weak metal-metal bonding? (a) The alkali metals are less dense than other metals. (b) The alkali metals are soft enough to be cut with a knife. (c) The alkali metals are more reactive than other metals. (d) The alkali metals have higher melting points than other metals. (e) The alkali metals have low ionization energies.

If you want to make a polymer for plastic wrap, should you strive to make a polymer that has a high or low degree of crystallinity? \(12.90\) Indicate whether each statement is true or false: (a) Elastomers are rubbery solids. (b) Thermosets cannot be reshaped. (c) Thermoplastic polymers can be recycled.

Look up the diameter of a silicon atom, in \(\hat{A}\). The latest semiconductor chips have fabricated lines as small as \(22 \mathrm{~nm}\). How many silicon atoms does this correspond to?

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