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? 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 termed 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) As temperature increases the average kinetic energy of the particles increases.
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.
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. ... A covalent bond involves a pair of electrons being shared between atoms. Atoms form covalent bonds in order to reach a more stable state.
e) In molecular solids relatively weak intermolecular forces bind the molecules in the crystal lattice, so relatively little energy is required to disrupt these forces.