Explain the following:
a) Why does increasing the temperature cause a substance to change in succession from a solid to a liquid to a gas? Explain.
b) Explain why a liquid has a definite volume but a gas does not?
c) Discuss how does an amorphous solid differs from a crystalline solid?
d) Explain with examples, how bonds are formed in ionic compounds and covalent compounds.
e) Covalent bonding occurs in both molecular and covalent network solids. Why do these two kinds of solids differ so greatly in their hardness and melting points?
a)Kinetic energy increases with temperature. As the kinetic energy rises with temperature, the intermolecular forces of attraction are overcome by increasing molecular motion.
b)In a liquid, the particles are still in close contact, so liquids have a definite volume. However, because the particles can move about each other rather freely, a liquid has no definite shape and takes a shape dictated by its container. Particles are free to move over each other, but are still attracted to each other.
c)Crystalline solids have well-defined edges and faces, diffract x-rays, and tend to have sharp melting points. In contrast, amorphous solids have irregular or curved surfaces, do not give well-resolved x-ray diffraction patterns, and melt over a wide range of temperatures.
d)Ionic bonds form when a nonmetal and a metal exchange electrons, while covalent bonds form when electrons are shared between two nonmetals. An ionic bond is a type of chemical bond formed through an electrostatic attraction between two oppositely charged ions.
e)Covalent bonding occurs in both molecular and covalentn etwork solids. ... Since intermolecular forces are weaker than intramolecular forces, breaking covalent bonds require more energy than breaking the attraction of intermolecular forces. That is why covalent network solids have high melting and hardness.