LANGUAGE OF CHEMISTRY

PART 1

Hey guys, I am Avin Prakash and I am an ICSE board student. From my experience, chemistry is a tough subject to understand sometimes, especially when you target a particular chapter at a time. Some references are given in books, for which you have to toss and turn the pages, and sometimes, many students (like me) target definitions first, and then the smaller tits and bits of fact. Some guys just have trouble putting it all in mind, and then they slowly develop a phobia for it. So I have written an article here, hoping to help.

Let’s see,

Firstly, many times you encounter questions (not just in exams) that are actually just too basic to explain. Such as: What is chemistry?

“Chemistry is the study of matter.” It’s as simple as that.

Coming back to the topic, when we talk about the language of Chemistry, we start one step at a time. Let me explain what these steps actually are. You see, when you start speaking about chemistry, then you can start by classification of matter. Matter can either be a pure substance or a mixture. Now a pure substance can be either an element or a compound. Now there are 118 elements. They combine in fixed ratios to form compounds. And (just a fun fact, not in course) according to scientists, the last element will be the 137th element. So, in simplest words, the chemistry terminology cannot be confined to just one step. In fact, almost anything in chemistry cannot be confined into one step, though the course is much simpler.

So let’s begin,

Remember I said something about ‘pure substances’?

A substance made up of molecules containing the same kind of atoms is known as a pure substance.

Now, what are these ‘molecules’?

A molecule is the smallest particle that has the capability of independent existence. It exhibits all the properties of that element.

What is an ‘element’?

An element is a pure and simple substance that cannot be decomposed into simpler substances.

Fine, but we actually left something in pure substances, what are these ‘atoms’?

Atoms are the smallest part of an element that may or may not have an independent existence but can take part in a chemical reaction.

Wait for a second, independent existence? This is causing a little trouble, isn’t it? Molecules and atoms… Hmm…

Molecules are made up of atoms. It doesn’t matter whether there is just one atom or two or three or four of eight atoms.

Now here comes a new term from the above statement, ‘Atomicity’.

The number of atoms in a molecule is known as atomicity.

Now, elements containing only one atom are known as Monatomic, Elements containing two atoms are termed as diatomic, for 3 triatomic, for four we have the term tetratomic and for 8 octatomic.

But I also said something like ‘compound’, isn’t it?

Elements combine chemically in fixed ratios to form compounds.

But… I am speaking normal English, right? Now I will pull you guys into the history of the language of chemistry. Now, before 1600 AD, there used to be guys known as Alchemists. They tried to turn stuff into gold. But- when a doctor gives you a prescription to add to your medical history like this alchemists also used to write down their observations using symbols. They used various symbols like a crescent, and each symbol represented a different thing. Then came a system proposed By John Dalton, who had also proposed the atomic theory, which is said to have laid the foundations of modern chemistry. He also used invented a new set of symbols, like an empty circle for oxygen, a circle with a dot in the centre for hydrogen, a black coloured circle for carbon etc.

Then came Sir J. J. Berzelius. One of the most celebrated scientists for purposing the modern system of symbols suggested a method that laid the foundations of the IUPAC (International Union Of Pure And Applied Chemistry) system of symbols.

A symbol is a short form that stands for an atom of an element or the Abbreviation used for that element.

Now, let’s see-

I am pretty sure you all have seen the periodic table. If not, then Google it and see at the table that appears.

The first element is Hydrogen represented by an H. Then the second element is Helium represented by He.

What do we find here?

Some elements such as Hydrogen are named after their first letter.

Some elements, in order to avoid confusion, are named after their first and another letter like Helium.

(NOTE: The first letter of the symbol is always capitalized and the second is in lower case. Why? Let me give you an example, suppose the element Cobalt. Its symbol is CO ;) Just kidding. If I am correct, then you would have already got my point. CO actually stands for Carbon Monoxide, which is a highly toxic gas. The symbol of cobalt is Co. Got my point? Tell me in the comments down there.)

Now, there is something else as well, what about the element Iron? There is a symbol Fe written there. I’ll tell you why. Fe stands for Ferrum, and it’s actually a Latin name of Iron. (I am pretty sure chemistry would have gotten a bit interesting for Percy Jackson fans, After all, he was also Greek. And here’s one more thing for Percy’s fans, remember Argentum and Aurum, the dogs of Reyna, were actually named after the Latin terms for Silver and Gold respectively).

See, as I am teaching like every concept is clear by roots, so I will explain one more thing which was there in class 8th. An atom is made up of subatomic particles, Proton, neutrons and electrons. In simplest terms, a proton is present in the centre of the atom with neutrons which carries positive and neutral charges respectively. Electrons revolve around the nucleus at a very high speed (equal to the speed of light) around the central part and it carries a negative charge.

Now, what happens is that the electrons are arranged in shells or orbits. The number of electrons is equal to the number of protons normally. But there is another problem- the last shell (also known as valence shell) has to have eight electrons (also called an octet). In the case of hydrogen, it requires a duet. (There is another part of the explanation on it, but as I have said, chemistry is endless. You can just search for electronic configuration- and I am sure that it will help.)

So, how will an atom achieve that? It will have to lose, share or gain electrons. If it will gain electrons, it will become negative, and if it will lose electrons, then it will become positively charged. We give these charged atoms a special term- ions.

An ion is an atom (or a group of atoms) formed by loose or gain of electron(s) by an atom (or a group of atoms). Positive ions are known as cations and negative ions are known as anions.

Now we are getting somewhere- gain, lose or share. Now there is another term, valency.

Valency can be defined as the number of electrons an atom can gain, lose or share.

Another definition of valency is:

Valency can be defined as the measure of the combining capacity of an element.

How to calculate the valency of an atom?

(I HIGHLY RECOMMEND STUDYING ELECTRONIC CONFIGURATION BEFORE READING THIS) It is simple. If the number of electrons present in the valence shell is less than 4, then just put a plus sign before the number of valence electrons (means that the atom loses electrons and accumulates the positive charge) and if it is more than four, add it to -8. You have your valency.

So we get that an element forms a compound when it loses, gains or shares electrons.

But, there is still one more thing- An atom can lose electrons from its valence shell, but what if it does so from its penultimate (second last) shell as well? Then it can have more than one valency! And you know what, this phenomenon happens, and it is termed as variable valency.

Certain elements show more than one valency i.e. variable valency.

But wait, what if more than 2 elements combine? Yes, there are such types of compounds such as KOH (Potassium Hydroxide). But in this case, the Potassium acts as the positive unit and the Hydroxide acts as the negative unit. These ‘units ’ have a special term, radicals.

Radicals are atoms or a group of atoms that acts as a single unit and carries a positive or negative charge.

The positive radicals are known as Basic or electropositive radicals whereas the negative radicals are known as Acid or electronegative radicals. Like in this case, Potassium is the positive one and Hydroxide is the negative one.

But KOH, how do we name it?

There is another term here, formula.

The symbolic representation of a molecule is known as Formula or Molecular formula.

This article will be continued….