The concept of chemical elements

Through Robert M. Hazen, Ph.D., George Mason University

The nature of the chemical elements themselves is very complicated. Long before the existence of atoms was proven, there were still chemical researchers around the world looking for useful compounds. And some of the substances they found seemed more basic than others. These “elements” cannot be broken down into other substances by any normal physical or chemical means.

Chemical elements are the most basic substances in nature. (Image: Tonhom1009 / Shutterstock)

Most famous chemical elements

Many people may know that water can be broken down with an electric current. And it breaks down into two gases: hydrogen and oxygen. But no matter what is done, it doesn’t seem possible to break down hydrogen and oxygen into simpler compounds. They seem more basic. They are chemical elements.

Ancient cultures knew of at least ten different chemical elements. Most of them have been found in their original condition, most of them have been found as metals. There are precious metals like copper, silver, and gold. They are common enough to be noticed; they are tough enough to be useful; they are rare enough to be valued.

Platinum is also a precious metal. Interestingly, platinum was not recognized in Europe or Asia, but it was used by pre-Columbian people in the New World, in part because platinum nuggets could be found in the stream beds of some parts. from South America.

This is a transcript of the video series The joy of science. Watch it now, on Wondrium.

Natural chemical elements

Other metals are also rarely found as native elements under unusual circumstances. There is iron, found in the form of meteorites. Small amounts of lead, small amounts of mercury can be found in certain types of places. And so these also occur uncombined in nature; they are also natural elements. These metals, along with tin and antimony, could be produced in a fire from ordinary ores.

Indeed, some of these elements may have been discovered by chance. An ore just falls into a fire, and a little bit of that metal, antimony or tin, could be pulled out that way. There are also non-metallic elements found in nature. Carbon comes from charcoal and sulfur from volcanoes. Beautiful yellow sulfur crystals can be found near the mouths of some volcanoes. All these elements, moreover, are still extracted in large quantities today.

Learn more about the chemistry of carbon.

Period of alchemy and the discovery of chemical elements

From the 12th century to the 16th century was the period of alchemy, where various scholars learned to separate a few other elements using intense fires. New elements discovered during this time include arsenic and zinc, bismuth and phosphorus. Between 1735 and 1805, chemists devised new techniques to purify and characterize more than two dozen new elements. This research goes hand in hand with advances in mineralogy.

Many of the new elements were discovered by studying the minerals by wet chemical analysis, where the minerals were dissolved or broken up, or by torch analysis, where a very hot flame was used to melt and fuse various parts of the minerals. And from time to time, a new element appeared as well.

The important elements – nickel, cobalt, magnesium, chromium, molybdenum, tungsten, uranium – were all discovered during this period. Also, during this period was the first isolation of gaseous elements. Hydrogen, nitrogen and oxygen were all isolated between 1772 and 1774.

Learn more about states of matter and state changes.

Joseph Priestley and the dramatic discovery of oxygen

Portrait of Joseph Priestley.
Oxygen was discovered by British chemist Joseph Priestley. (Image: author unknown / public domain)

The most spectacular of these discoveries was made by British chemist Joseph Priestley, who lived from 1733 to 1804. It was in 1774 that Priestley submitted mercury oxide, or HgO, a common mineral that can be collected on the surface of the Earth. .

He subjected it to a temperature of about 450 degrees centigrade, which caused a puddle of mercury to form at the bottom of his flask and the release of a gas, which turned out to be oxygen. .

He collected this gaseous oxygen in his containers, and he discovered that it is the gas that is essential for all combustion processes. Indeed, he wrote: “What surprised me more than I can express is that a candle was burning in the air with a remarkably bright flame. So he had discovered a pure source of oxygen.

Using the battery to discover new chemical elements

The battery provided an important new technique called electrolysis. And by this electrolysis technique, new elements can be produced and isolated. The battery was invented by Luigi Galvani, who placed an alternating sequence of plates – for example, zinc, silver, zinc, silver – in an acid bath to obtain an electric potential.

An image of powerful batteries in a power plant.
Batteries were used to separate the chemical elements. (Image: tong patong / Shutterstock)

Electrolysis works like this: a chemical compound is dissolved in an acid bath, then this acid bath is subjected to electric current. These alternating metal plates create a positive electrode and a negative electrode.

Metals often settle on the negative side, the anode side, while non-metals concentrate on the cathode, the positive side, of this acidic bath. And in this way, new elements can be isolated, one going to each of the two electrodes in some cases.

The use of drums to discover new elements began in 1797. British chemist Sir Humphry Davy was a great lecturer in London. He used increasingly powerful batteries to separate potassium and sodium, boron, calcium, barium, cadmium, all very important elements which were first separated and isolated by Davy at the using its battery.

Common questions about the concept of chemical elements

Q: What are the chemical elements?

Chemical elements are basic substances in nature discovered by researchers before the existence of atoms was proven. These “elements” cannot be broken down into other substances by any normal physical or chemical means.

Q: How was oxygen discovered?

Oxygen, among the best known chemical elements, was first discovered by chemist Joseph Priestley. He was able to extract pure oxygen from the mineral mercury oxide.

Q: Who was Sir Humphrey Davy?

Sir Humphrey Davy was a British chemist who discovered many chemical elements such as calcium, barium, cadmium, sodium and potassium using batteries that provide a technique called electrolysis.

Keep reading
Maxwell’s equations: the great discovery of electromagnetism
Faraday and the phenomenon of electromagnetic induction
Hans Christian Oersted and electromagnetism

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