My Science School

A stone wall is hard, water is wet, and the air is invisible. But they are all matter, and they are all made up of molecules. Even so, they behave in different ways. So we say that they are different forms of matter.

Stone is a solid. It has a shape of its own. The molecules in most solids are very close together. They pull hard on each other. This pull makes solids keep their shape.

Water is a liquid. It has no shape of its own. It takes the shape of the container it is in. Molecules in most liquids are further apart than molecules in a solid. They don’t pull as hard on one another. So the molecules of a liquid can slide around and take any shape.

Air is a gas. It has no shape of its own, either. Its molecules are so far apart that they hardly pull on one another at all. Molecules of a gas bounce around so easily that they can squeeze into a small balloon or spread out to fill a big room.

Most kinds of matter are compounds – they are formed when elements join together. Just as the tiniest bit of an element is called an atom, the tiniest bit of a compound is called a molecule. A molecule is a group of joined atoms.

Molecules can be very simple. When you breathe air, your body takes in molecules of a gas called oxygen. Each oxygen molecule is made up of two oxygen atoms joined together.

But some molecules have many kinds of atoms. The “vinegary” taste of vinegar comes from a molecule containing two carbon atoms, four hydrogen atoms, and two oxygen atoms. And some molecules are made of thousands of atoms. Bread and potatoes contain giant molecules that look like chains - the chains have thousands of molecules.

Atoms and molecules follow the rules of chemistry and physics, even when they’re part of a complex, living, breathing being. If you learned in chemistry that some atoms tend to gain or lose electrons or form bonds with each other, those facts remain true even when the atoms or molecules are part of a living thing. In fact, simple interactions between atoms—played out many times and in many different combinations, in a single cell or a larger organism—are what make life possible. One could argue that everything you are, including your consciousness, is the byproduct of chemical and electrical interactions between a very, very large numbers of nonliving atoms!

Picture Credit : Google

It was the 1890’s, and a young Polish-born scientist named Marie Sklodowska Curie hurried home through the streets of Paris. But her thoughts were back in the unheated, leaky shed where she worked. She was puzzling over an experiment she had done over and over. The result had been the same each time, but she could not explain why!

In this experiment, Marie used a rock called pitchblende that gave off mysterious rays of energy. These rays were like a signal, but the signals made no sense at all.

Marie believed that the signals from the rock might be coming from an element that no one knew about. So she began trying to find it. She boiled the pitchblende in huge pots. Next she added chemicals to it to break up the different compounds. Then she tested each part to see if it gave off rays. Her work took a long time and many of her experiments went wrong.

Finally, in 1898, Marie found the element that gave off the energy. She named it radium. The radium gave off so much energy that it glowed in the dark! It took Marie four years and several thousand kilograms of pitchblende to get just a tiny pinch of pure radium.

Marie’s work was hard, but it paid off. In 1903, she won a Nobel Prize, the most important award in science - and she gave the world a new element.

So many that if you started to count them, you probably would never finish.

But if you could sort out the atoms in all that matter, you would find that there are only about 100 kinds. Each of those 100 kinds of atoms is a different size.

Some kinds of matter are made up of only one kind of atom. These kinds of matter are called elements.

Gold is an element. A piece of pure gold is made of just gold atoms. Iron is an element, too. It is made of just iron atoms.

But most kinds of matter are made of two or more different kinds of atoms joined together. These kinds of matter are called compounds.

Water is a compound made of two elements, an element called oxygen and an element called hydrogen. By themselves, oxygen and hydrogen are invisible gases. You cannot see them. But when they join together, they make a liquid you can see and feel – water.

Sulphur dioxide is another harmful gas that comes from power stations and vehicles. It is very acidic, which means it eats things away. In the atmosphere, it mixes with droplets of moisture to make acid rain. Trees die when acid rain falls on them and on their soil.

Is it true? Some polystyrene burger cartons are bad for the Earth’s atmosphere.

Yes. Some of them are because they’re made using chemicals that damage the ozone layer. Many cartons are now made without these harmful chemicals.

Is Earth’s atmosphere being harmed?

There is a layer of helpful gas around the Earth called ozone. It protects us from the Sun’s dangerous ultraviolet rays. Unfortunately, the ozone layer is damaged because humans have put harmful chemicals into the atmosphere.

Amazing! When a nuclear power station at Chernobyl, Ukraine, exploded in 1986, radioactive material was sent into the atmosphere. Animals across Europe were contaminated by the radiation.

Is nuclear power dangerous?

Nuclear power stations do not burn fossil fuels. Therefore, they do not make harmful gases. But they do make radioactive waste material. It is dangerous and will have to be guarded for many years into the future.

Picture Credit : Google