My Science School

Rubidium, atomic number 37, was discovered in 1861. It was discovered in Heidelberg in Germany by Robert Bunsen and Gustav Kirchhoff using spectroscopy. This method was invented and developed by the pair in the previous two years. At the heart of the spectroscope there is a glass prism, which splits the light coming from a flame into a spectrum. This is very similar to how raindrops can split sunlight into a rainbow.

When different salts were placed in the flame of the recently invented Bunsen burner, Bunsen and Kirchhoff saw coloured lines in all the spectra they saw. What was more exciting was that they discovered that these coloured lines were unique to the substance that was burnt. They concluded that the lines in a spectrum were a way of finger-printing an element.

In 1861, the duo began studying the mineral lepidolite (a lithium, potassium and aluminium silicate). This mineral was found in Saxony, Germany. Bunsen and Kirchoff used hydrochloroplatanic acid to isolate potassium chloroplatinate from the mineral. In potassium chloroplatinate that was isolated, they found another salt. This salt produced a spectrum containing many new lines when it was placed in the Bunsen burner. Two of the lines that were produced were particularly outstanding. It was a new element. They named this new element rubidium (and the symbol Rb) from the Latin word rubidius, which refers to the darkest red colour.

Picture Credit : Google

In 1825, a salt maker sent a sample of salt spring waters from Bad Kreuznach, a German town, asking chemist Justus von Liebig for an analysis. This sample had a very high amount of bromine in it, and Liebig had isolated it too. But he considered the substance as a compound of iodine and chlorine. Had he not taken it lightly, Liebig would have been the discoverer of bromine.

The next person in the story of bromine’s discovery is Carl Loewig, who discovered it while he was still a chemistry student at Heidelberg University in Germany. Loewig’s hometown was Bad Kreuznach, the same place from where Liebig had received the sample. Loewig took water from a salt spring in his hometown and added chlorine to it. He then shook the solution with ether and found that a red-brown substance dissolved in the ether. Loewig evaporated the ether to find bromine, a red-brown liquid.

Loewig’s professor at Heidelberg University asked him to prepare more of this substance for testing. But this took him a year, and by that time, in 1826, another person named Antoine Balard had discovered bromine and took the credit. Balard took brine (evaporated sea water in which salts have been concentrated) and crystallized salt from it. After that, he took the remaining liquid and mixed it with chlorine. Later, this solution was distilled, which left behind a dark red liquid-bromine.

Balard published his results in 1826, which provided evidence to the discovery. Since he was the first to publish, he came to be known as bromine’s discoverer.

Picture Credit : Google

Krypton was discovered by William Ramsay and Morris Travers in residue left from evaporating nearly all the components of liquid air. Within weeks, the duo had detected two other noble gases: neon and xenon. To honour their scientific spirit, King Edward VII made Ramsay a Knight Commander of the Order of the Bath in 1902. William Ramsay also received the Nobel Prize for Chemistry in 1904. It was awarded in recognition of his contributions in the discovery of the noble gases and for the determination of their places in the periodic table. Ramsay was also responsible for adding an entire new group to the periodic table. The only noble gas that he didn’t discover was radon.

Krypton is widely used today. It is employed in flashes for high-speed photography, in fluorescent lights along with argon, and in making neon signs that have a greenish-yellow light. (Neon alone glows red only).

Picture Credit : Google

Chlorine is denoted by Cl and its atomic number is 17. Sodium chloride or salt is a very common compound of chlorine, which has been in use since ancient times. Evidence suggests that rock salt has been used as early as 3000 BC. In 900 AD, a Persian alchemist named Rhazes prepared hydrochloric acid, another compound of chlorine. In 1200 AD, a mixture of hydrochloric acid and nitric acid was used to dissolve gold. This process released chlorine gas, but it was not known at that time.

The first person to isolate chlorine gas was Carl Wilhelm Scheele, a Swedish chemist in the year 1774. As a result, he is credited for discovering chlorine. But he did not know that it was an element. It was only in 1810 that Sir Humphry Davy realized that Scheele had actually discovered a new element. Scheele, on the other hand, had studied its properties and discovered that it could kill insects, had a green yellow colour and that it bleaches litmus paper. Chlorine has many practical purposes in our life. It is used to purify water, to prepare disinfectants, in bleaches and in mustard gas. It is also used to manufacture many products directly or indirectly. For example, it is used in paper production industry, in making dyes, antiseptics, insecticides, paints, petroleum products, plastics, medicines, textiles, solvents and even some food items. It kills bacteria and microbes in the drinking water supplies. Chlorine is also used to bleach wood pulp for paper-making and to remove ink from recycled paper.

Picture Credit : Google

The element with the atomic number 34 is selenium. It was discovered by Jons Jacob Berzelius, a Swedish chemist, in 1817. He discovered selenium while analyzing an impurity in sulphuric acid that was produced at a factory in Sweden. Berzelius thought that this impurity was tellurium at first, but he then realized that it was an unknown element. And because of its similarity to tellurium, he named it selenium after the word Selene - a word in Greek that means ‘moon goddess’.

Selenium began to be used on commercial levels by the mid-1870s when it was developed by Werner Siemens. A selenium cell was used in the photo-phone developed by Alexander Graham Bell in 1879.

This metal is also nutritionally essential for humans. We need selenium for healthy joints, hearts, and eyes. It is critical in DNA synthesis, in the activities of the immune system, and the reproductive system. Selenium also helps fight cancer, among other diseases. The human body cannot synthesize this element, and therefore, we have to provide it from outside sources. However, a little selenium is all that is needed for healthy functioning and too much selenium can be toxic.

Selenium exists in several allotropic forms, of which only three are generally recognized. Amorphous selenium is either red, in powder form, or black, in vitreous or glassy form. Crystalline hexagonal selenium is the most stable form of this metal. It resembles sulphur in its appearance.

Picture Credit : Google