Category Metals and Non Metals

What do we know about the platinum group of metals?

A group of six metals – ruthenium, rhodium, palladium, osmium, iridium, and platinum-are known as the platinum group of metals or PGM. The group is called by this name because platinum is found more than the others though all of them are very rare.

The platinum groups of metals have physical, chemical and anatomical similarities. They are dense, stable and are often recycled to have longer lives. The group has a variety of highly specialized uses.

Platinum is a silvery white metal that is more expensive than gold. It is used to make jewellery. Platinum and palladium are often used as catalysts. Iridium and rhodium are harder and have a lot of alloying applications. There are very few minerals containing the platinum group of metals, and they are found mainly in South Africa and Russia.

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Why is radium not widely used now?

No one knew of the dangers radium posed when it was produced for the first time. Radium had an aura of mystery which attracted people. Moreover, people were fascinated by how it glowed when mixed with phosphor. No wonder, industries sprang up to manufacture hundreds of consumer products containing radium.

The health hazard caused by this fascinating new element was identified only later. The harmful effects of radium such as skin burns and hair loss were observed among early experimenters. Many of them died as a result of their work.

The widespread use of radium was later halted for health and safety reasons. But, its wide use in luminescent paints continued through World War II. The soft glow of radium’s luminescence made aircraft dials, gauges and other instruments visible to their operators at night.

Radium was also an early radiation source for cancer treatment. Small radioactive seeds were implanted in tumours to kill cancerous cells. Safer and more effective radiation sources are used today.

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What do we know about the discovery of radium?

The discovery of radium is one of the most interesting stories in science. The story begins with the research of the French physicist Antoine-Henri Becquerel of the ore called pitchblende containing the element uranium. Becquerel found that pitchblende gives off radiation.

Becquerel’s discovery caused great excitement among scientists. Many physicists stopped their own research and began to study this novelty. A scientist couple Marie and Pierre Curie were especially interested in pitchblende.

Eventually, they isolated a new element that gave off more intense radiation than pitchblende itself. The Curies named this new element polonium. That was not the end. They believed that there would be at least one other element in the pitchblende.

The couple continued with their studies and in 1898, they isolated a second new element- radium. Radium gave away intense radiations and it took the Curies another four years to prepare one gram of the element. To do so, they had to sift through more than seven metric tons of pitchblende!

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Is strontium dangerous?

Strontium is a silvery metal that rapidly turns yellowish in air. It is found as a free metal in nature and is not dangerous. This is because the naturally occurring strontium is not radioactive. But strontium has some isotopes that are highly unstable and potentially dangerous. Strontium-90 is one such isotope of strontium.

Strontium-90 is produced as a result of a nuclear reaction. It became famous in the 1960s when it was produced as the result of an atomic bomb testing. In fact, when a nuclear explosion takes place, the tens of millions of tons of earth and rock that are thrown skywards contain strontium-90.

Strontium-90 contaminates air, water, soil and vegetation; severe radiations produced in the process can sicken both animals and humans and can even result in deaths.

Strontium-90 affects human bone tissues, marrow and blood. It can cause leukaemia and bone cancer too.

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Why was strontium used in ancient India?

Let us now talk about something that was common in ancient India. Very often, mysterious red lights would flare up in temples to the awe and terror of worshippers, who believed it to be a divine light.

Actually, it was the handiwork of priests who would quietly set fire to small balls of a mixture that contained strontium salts. Strontium catches flame spontaneously in air and strontium salts impart a beautiful crimson colour to flames. For this reason, strontium is used in fireworks as well.

Strontium is a soft silvery metal that is found chiefly as celestite and strontianite. It was in 1808 that Sir Humphry Davy isolated strontium. But much before that, our ancestors knew about this metal and had used it in quite a cunning manner.

You might have heard stories about ships that sent red flares as a symbol of trouble. Just like the ones used in ancient Indian temples, these ships too used strontium salts. It would not be wrong to say that strontium has saved many lives.

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Why is calcium used to make glass?

Let us now take a look at how glass is made. Glass is made by melting a special type of sand called silica sand. The sand melts at 1700 degree Celsius; it must be melted and cooled down quickly. This process requires a huge amount of energy and will produce a lot of heat.

To make things easier, sodium carbonate is added. Sodium carbonate breaks down in the heat to form sodium oxide, and reduces the melting temperature. This does not completely solve the problem.

The glass made after adding sodium carbonate would dissolve in water. This is where calcium carbonate comes into the scene. When calcium carbonate is added to glass, it forms calcium oxide in the glass. About 90 per cent of glass in the world is made in this fashion.

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Why is calcium important for our health?

You cannot lead an active life without calcium. Be it walking, running, playing games, lifting things or even sitting straight, you cannot do any of these if not for calcium.

Every cell in our body needs calcium. Calcium helps our muscles work and send nerve impulses. It helps your body to heal cuts, scrapes and other injuries. Our bones store calcium that is necessary for our blood and cells; our bones are built and strengthened with calcium right from the day we are born.

If our diet does not include enough calcium, our body will consume the calcium that is stored in the bones. This will eventually make our bones weaker. So, it is important to have calcium rich foods like curd and milk.

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Why are chalk, limestone and marble important?

Chalk is a white crumbly rock made of microscopic shells and is rich in calcium carbonate. Chalk is softer than limestone and is used to make a substance called putty. Putty is used to fill holes in woodwork, give a smooth finishing to the walls of buildings and seal glass into windows. Chalk is also ground into a powder called whiting, which is used in crayons, rubber paints and cosmetics.

Limestone often contains the fossils of dead animals and plants that were trapped in between the layers of sediment. Limestone is hard enough to be qualified as a building material; it is used to construct buildings, walls and paving stones. Sometimes, limestone contains phosphates. This is used to make fertilizers.

Marble is formed when chalk or limestone is buried deep underground. The pressure and heat changes the limestone or chalk into marble. It is hard, yet shiny and beautiful. Therefore, marble is used in flooring. Many sculptures and buildings around the world are made of marble. The famous Taj Mahal is built entirely of marble.

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Why is it said that calcium carbonate is found in rocks?

Calcium makes about 3.6 per cent of the Earth’s crust. But it is rarely found as a free metal. Calcium is abundant on the surface of the Earth and is mostly found as chalk, limestone, or marble.

Let us now look at how these calcium deposits are formed. The shells of living things in the ocean are made of calcium carbonate. When they die, they sink to the bottom of the ocean. Over the years, these form layers of sediments. As the layers build up, their weight squeezes the water trapped between and they stick together. Over thousands of years, the shells are transformed into sedimentary rocks called chalk, limestone and marble.

It was Sir Humphry Davy who isolated calcium for the first time in 1808.

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Does magnesium have a role in our health?

To maintain good health, the human body needs a lot of minerals like iron, calcium and sodium. We have already discussed how our blood is enriched by iron. But, very few people are aware of the enormous role magnesium plays in our bodies.

After oxygen, water and food, magnesium may be the most important element needed by our bodies. In fact, it is by far the most important mineral in the body.

Magnesium is necessary for over 300 different biochemical reactions that help the functioning of the human body. Magnesium is necessary for the growth and strength of bones and teeth. It plays an important role in the synthesis of protein and is responsible for fighting infections. Magnesium is vital for muscle contraction and the functioning of nerves.

Needless to say, we need to eat a lot of food that is rich in magnesium like nuts, whole grains, dark green vegetables, seafood, and cocoa.

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