Looking at chemicals, touching them,(only if harmless) smelling them and mixing them with water and some other chemicals can be an exhilarating experience for boys and girls. Ali and Nelly had been given a code of conduct, what to do and what not to do.
Here is the code of conduct:
1. You have to be over 12 years to start collecting chemicals. Always it is safer to get an adult to help you especially if you are below 14 years.
2. Use only safe chemicals .
3. Never play with chemicals.
4. Never mix more than two chemicals at a time unless guided by a teacher..
5. Observe all changes from a safe distance and from a side only. If you look from above chemicals can spurt out on to your face.
6. Wear gloves and goggles when ever possible.
7. Wash your hands with soap and water after touching chemicals.
Fig. Ali heating a copper wire in a gas flame.
Ali selected to study Copper which is a metal. After noting the appearance, he did a series of tests and recorded as follows. You also can do these experiments and find out what happens. Sometimes there can be an interesting change. The substance may change, the flame may change. But at other times there may not be an important change; then you can write “no change”
TESTS and OBSERVATIONS
In the same way you can study the other metals too. Some examples of metals and non metals are given here.
Now Nelly wants to know, what exactly is a chemical substance.
‘A chemical’ may be defined as a substance that will maintain the same consistency.
All chemicals are divided into two main groups,
Elements and
Compounds. Today we shall limit our attention only to
ELEMENTS
There are only about one hundred and twelve natural elements in the entire Universe. A few have been made by man.They generally last only for a few seconds.
These can again be divided into
‘Metals’ and
‘Non-metals’.
A FEW EASILY OBTAINABLE METALS
Know the Metals,
|
Description
|
From where to get.
|
Copper
Cu |
Orange solid
Magnet will not attract.
|
From old electrical wires. |
Gold
Au
|
Yellow solid.Has a permanent glitter.
|
Your chains,bangles etc. (Too precious to play with) |
Silver
Ag |
Silver solid. Fairly light.
Glitter fades slightly, Used in jewellery.
A photo of a nugget.
A magnet will not attract.
|
Jewellery.
Too expensive.
|
Aluminium
Al
|
Glitter fades under certain conditions.
|
Chocolate wrappers and some cooking foil etc |
Iron
Fe |
Silver colour when fresh. Glitter is short lived.
Magnets attract.
|
Rusted tin cans and nails which have to be cleaned with sand paper. |
Magnesium
Mg
|
Silvery when cleaned. fairly light
Glitter fades.
|
Chemical suppliers |
Lead
Pb
|
Greyish silver. A heavy metal
Lead vapour is a dangerous poison
|
Present in solder. |
Mercury
Hg |
Silver coloured liquid.Very heavy.
Mercury can go into other metals and spoil them
Vapour is poisonous.Should never be spilled.
|
Present in many instruments like some thermometers. but difficult to get |
WARNING
• The test tube must be moved up and down so that heating will not be only at the bottom.
• STOP heating when sulphur melts.
• The mouth of the test tube must be directed away from you so that nothing from any spurt will come to you.
• On cooling sulphur will adhere to the test tube. It must be removed by melting.
.
Fig. Nelly heating sulphur in a test tube with a spirit lamp.
WARNING
The gas comes out when sulphur burns is poisonous. If you wish to burn this it has to be done outdoors.
SOME EASILY OBTAINABLE NON-METALS
Non- Metal
|
Description |
Sources |
| Carbon C |
Usually a black solid present in many forms A crystalline colourless form exists as Diamonds
|
Lamp black (soot) Char coal, Coal., graphite |
| Sulphur S |
A yellow solid |
Very common used as a fungicidein agriculture..The gas comes out when sulphur burns is poisonous. If you wish to burn this it has to be done outdoors. |
Iodine
I |
Dark purple crystals
|
Used to be available in pharmacies.
|
Most of the other non metallic elements are either gases , such as Oxygen, Hydrogen, and Chlorine or far too dangerous to keep such as Phosphorus.
A few days back Ali and Nelly started collecting Elements. Now they wish to add compounds to their collection.
Fig.1 What we must know about elements and compounds
It has been shown that there is copper in Copper sulphate. Copper remained hidden. Today let us take a few more cases.
Water, one of the most common chemicals is a very good example of a compound. It has Oxygen atoms and Hydrogen atoms.
Fig.2. The illustration shows the difference between elements and a compound.
In this illustration, atoms are represented as babies. Molecules are compared to groups of babies holding hands. One molecule of Oxygen joins with two molecules of Hydrogen to form two molecules of Water. This is what happens when Hydrogen burns.
Ali and Nelly knew compounds cannot be collected in metal cans. So Ali decided to use plastic cans, things like yoghurt cups , while Nelly opted for glass bottles such as vanilla bottles from her mom. Here we give what they have collected so far .
As you go along with your collection, you must have a Note book with as many pages as you can get. You can give a page for each chemical. You can write everything you learn about every chemical you have. Page no. can be included in the sample.
Nelly wanted to include liquids and gases also in her collection. While solids are better kept in jars with a wide mouth, the liquids need bottles with narrow necks. Their stoppers may be cork, rubber or plastic. Gases have to be collected dissolved in water.
Nelly’s Note Book
1. H2O2 Hydrogen peroxide.
This is available as a colourless solution in dark bottles as they break down due to light.
When added to wounds oxygen that comes out can kill germs.
2. MgSO4 Magnesium sulphate ( Epsom salt)
Used in bath salts and on the skin to reduce swellings.
White crystals. Soluble in water.
3. CuSO4 Copper sulphate
Blue crystals soluble in water.
There are only a few compounds discussed here. The American Chemical society has categorised over 23 million compounds. This number is daily increasing as the man is making more and more new compounds . All kinds of plastics and medicines are some recently made compounds. Glass may be considered as one of the earliest man made compounds.
MIXING CHEMICALS
In mixing chemicals to study reactions it is very important not to mix this and that like a mad man.
Ali and Nelly started the experiment in a very professional way. They made a solution of Copper sulphate into a bottle. Then they took a set of test tubes. Then they added 3cm of the solution into a number of test tubes. Instead of test tubes you may use small plastic or glass bottles.
Substances may be added in the form of a few drops of solution. Ali used a drinking straw while Nelly used a sucker to add the drops. When you dip a drinking straw into a solution. Liquid comes in. If you close the top with your finger and take it out the liquid will not come down.
WARNING- ............Never suck in solutions with your mouth.
|
Project
Refer Chemistry books for properties of metals and non metals.. The Periodic Table gives a complete list of elements..
