18.The octet rule tells us that in every chemical reactions, elements will either gain or lose electrons to attain the noble gas electron configuration. This stable electron configuration is known as the octet configuration since it is composed of 8 valence. Oxygen’s electron configuration is 1s2 2s2 2p4. So when oxygen reacts with other elements to form compounds, it completes the octet configuration by taking 2 electrons from the element it reacts with
19. Actually pure metals are made up not of metal atoms but rather of closely packed cations (positively charge particles). These cations are then surrounded by a pack of mobile valence electrons which drift from one part of the metal to another. This is called metallic bond.
20. This is the energy which is needed to break a single bond. When the dissociation energy is large, this means that the compound is more stable. Since carbon to carbon bonds have high dissociation energy, therefore they are not very reactive.
21. Network solids are type of solids in which the atoms are covalently bonded to one another, so they are very stable. It takes higher temperature to melt them because breaking these covalent bonds required greater energy. Some examples are:
- Diamond
-Silicon Carbide