Hello, students my name is Seema and I will be taking for you the chapter called as Periodic Classification of Elements. Now, in this chapter we will study the introduction and the need for classification. So, let’s get started.
Now, let me just give you a scenario, wherein you are going for shopping for the clothes of course. Would you like to shop for the clothes from place number 1 or from place number 2? Think and tell me which of the two will it be? Now, for me the answer will be 2. And you think why? Reason is quite simple, in the place number 2, I find that there is a systematic arrangement of clothes that have been done. So, my shopping becomes very easy. Now, you might have realised these days in the shopping centre the clothes over there, they are arranged according to the brand and in each and every brand the clothes they are further arranged according to the sizes and they are also arranged according to the colour. So, I can pick that one particular size, one particular brand and one particular coloured clothes that easily. And my task is done.
And now let us try to change the scenario and let us say this time you are going for the shopping of books and not clothes. Now, would you like to shop for your books from place number 1 or from place number 2? Again think deeply and tell which of the two it will be? For me again the answer remains the place number 1. And you think why? Reason is still the same in place number 1, I find that there is a systematic arrangement of books that have been done. So, it becomes very easy for me to pick that one book. Why, because you might have noticed that nowadays in modern libraries the books over there are arranged as per the genres, they are arranged according to the name of the author and even the name of the author they are arranged in alphabetical manner. So, it becomes quite easy to pick that one book. But you might be wondering that in chemistry why am I relating to systematic arrangements again and again. The reason for this will be unfolded in a short while.
Now, if you are talking about chemistry the most fundamental matter in chemistry is known as the ‘elements’. So, what exactly are these elements? An element is defined as a type of matter which is composed of only one kind of substance. Now how are we relating the systematic arrangement and the element? Let us look further, initially various scientists, they discovered various elements like gold. There was this element like silver, carbon, sulphur, iron and copper. These are few of the elements. And these elements based on properties they were classified as either being metals or being non-metals. For example, if I talk about element like copper, silver and iron, they are called as metals whereas carbon is called as non-metal. If it’s the element gold, it is definitely a metal and sulphur would become a non-metal. But what about element like silicon? Silicon and some other elements which showed the properties of both the metals as well as non-metals and they were known as metalloids. But this brings us to the conclusion that not all elements are metal or non-metal. Some of the elements can be metalloids as well. So, scientists came to the realisation that you know, we need a proper arrangement, a proper classification of elements, a proper study of elements.
Now, in nature as of now, if I am supposed to say, there are total of 119 elements, some of which you can see it over here. Now these 119 elements showed various properties, different properties and their understanding was also very important. That is why there was a need of systematic classification and arrangement of these elements in order to make their study easy. And this is what we are going to study in this chapter that is Periodic Classification. So, let us move ahead, let’s study efforts of classification in this chapter called as Periodic Classification of Elements.