The Challenge of getting an Element in its free state!

Why don’t we find elements in their free state?

We had read in the last chapter, that chemists had reached the conclusion that there are some basic elements that generate a variety of substances. They are 118 in number.

But it had also became clear that most of the elements are not naturally found in the element state. They are always found combined with another element.

Let us watch a video. In this video, you will see the element Sodium being cut. Look carefully at the layer that is cut and observe any changes on it.

Is there any change in the glow/shine of Sodium?

The reason for the shine to diminish can be chemically expressed as-

Sodium + Oxygen = Sodium Oxide

The element Sodium started reacting with the Oxygen present in the air and became Sodium Oxide. Due to this chemical reaction, the upper layer became dull/stopped shining.

Perhaps some of you will have an iron kadahi/wok/or deep frying pan at home for cooking vegetables. When we wash it and keep it aside, it gets rusty after some time. The reddish substance that collects on the surface of iron is called rust.

If you keep any iron object outside for a few days, it gets rusty.

Iron + Oxygen = Iron Oxide (the oxide of iron)

Phosphorous is an integral component of life. You have seen that phosphorous is found in bones and urine. It was first obtained from human urine. It is used in fields as a manure in the form of phosphate.

However, in nature, it is never found in its pure or elemental form. We find it as Calcium Phosphate in rocks.

Phosphorous  +  Calcium + Oxygen = Calcium Phosphate

You have now seen the three elements, Sodium, Iron and Phosphorous - they react chemically under standard temperature and pressure, as they are active in nature.

The substance that is formed after the chemical reaction is not reactive any more. It is stable.

For example, Sodium in its element form is very reactive. Whereas, in the form of Salt it is non-reactive.

Even pure iron starts reacting with oxygen very fast and becomes Iron oxide. Iron ore, from which we obtain iron, is usually in the form of Iron oxide.

Now take a look at the elements in the 18th column of the Periodic Table. They are known as Noble or Inert Gases. These are found in their element form in nature. They are stable and under  standard conditions they are non-reactive.

When a substance is made of two or more than two elements and its physical and chemical nature is different from that of the original basic elements, it is known as a compound.

Salt is a compound, made of Na and Cl. Chlorine in its basic nature is a light yellow gas and sodium is a shiny solid. When both combine, we get a solid salt and its nature is very different from that of either of them.

Similarly, water is also made of H and O. In their basic state, they are both gases, whereas water is a liquid.

Look all around you - you will find lots of compounds. Even if you search hard for elements, you wont be able to find them.

What about gold and silver? We see them, don't we?

Elements can be separated from their compounds only through chemical processes.

Here are some facts to remember-

1.     Some basic elements are stable, that is, they are found in their pure form. Their numbers are very few. For example, the inert, non-reactive gases in column 18.

2.     Most of the elements are found as compounds in nature, which are made of two or more than        two elements. For instance, Iron - in the form of iron oxide, Sodium - sodium oxide and    other forms, Phosphorous - in the form of Calcium Phosphate. 

3.     Compounds are stable as compared to elements.

Now we have found some more questions for which we need to find answers

1.     Why are inert gases, which are also called noble gases, non- reactive and stable?

 

2.     Why are certain elements like Sodium, Calcium and Iron, reactive?

 

3.     Reactive elements do not combine with any and every element to form compounds. Is there a  logic/plan to the process of making compounds?

If we understand the logic/plan of making compounds, maybe we can make a new compound?