IntroductionMore than 114 elements are known, which combine with each other in various ways to form millions of compounds. On the basis of their physical and chemical properties the elements have been classified, so that their characteristics could be generalised and easily learnt. These are classified into two main groups namely metals and non-metals. Of these elements, about 80 are metals and the rest are non-metals. In this chapter, we shall see that there are certain properties form a good basis for distinguishing metals from non-metals.
The metals are on the left hand side and non-metals are on the right hand side of the periodic table. They are separated from each other in the periodic table by a zigzag line. The elements B, Al, Si, Ge, AS, Sb, Te, are called Metalloids. They show both metallic and non-metallic properties. We use both metals and non-metals in our daily life. The characteristic properties of metals are quite different from those of non-metals. As we can see from the periodic table, there are only 22 non-metals. Of these, 11 are gases (hydrogen, nitrogen, oxygen, fluorine, chlorine, helium, neon, argon, krypton, xenon and radon), one is liquid (bromine) and the rest are solids. There are very few non-metals compared to metals, but they do form a very important class of elements.