Introduction: The Discovery of Two Elements

The periodic table is a fundamental tool for chemists, and it is home to over 118 known elements. Many of these elements were discovered in the 1800s, but there were still a few missing pieces to the puzzle. In the early 1900s, two elements were discovered that filled in some of those gaps: radium and protactinium.

Element 1: Radium, Discovered in 1898

Radium is a radioactive element with the symbol Ra and atomic number 88. It was discovered by Marie and Pierre Curie in 1898. The Curies were studying uranium and found that a sample of pitchblende, a mineral that contains uranium, was more radioactive than it should have been based on the amount of uranium present. They realized that there must be another element in the sample that was contributing to the radioactivity, and they named it radium.

The Curies and Their Research

Marie and Pierre Curie were a husband-and-wife team of scientists who were interested in radioactivity. They discovered polonium and radium, and their work was crucial to the development of nuclear physics. Marie Curie was the first woman to win a Nobel Prize, and she won two: one in physics and one in chemistry. Pierre Curie also won a Nobel Prize in physics, but he tragically died in a traffic accident before he could receive it.

Properties of Radium

Radium is a highly radioactive metal that is silvery-white in color. It is one of the densest elements and is highly reactive with other elements. It has a half-life of 1,600 years, which means that it takes that amount of time for half of a sample to decay into other elements. Radium emits alpha, beta, and gamma rays, which can be dangerous to human health.

Uses of Radium

Radium was once used in luminous paints, such as those used on the dials of watches and other instruments. It was also used in cancer treatments until the 1950s when it was discovered that the radiation emitted by radium could cause cancer. Today, radium is no longer used in any commercial applications.

Element 2: Protactinium, Discovered in 1913

Protactinium is a radioactive element with the symbol Pa and atomic number 91. It was discovered by Frederick Soddy and John Cranston in 1913. They were studying the decay of uranium and found that there was an intermediate element between uranium and radium that they named protoactinium (later changed to protactinium).

Frederick Soddy and His Discovery

Frederick Soddy was a British chemist who worked with Ernest Rutherford on the study of radioactivity. He discovered isotopes, which are atoms with the same number of protons but different numbers of neutrons. He also won a Nobel Prize in chemistry in 1921 for his work on isotopes.

Properties of Protactinium

Protactinium is a highly radioactive metal that is silvery-white in color. It has a half-life of only 32,760 years, which is relatively short for a radioactive element. It emits alpha and beta particles, which can be dangerous to human health. Protactinium is also highly reactive with other elements.

Uses of Protactinium

Protactinium has no commercial uses, but it is useful for scientific research. Because it is highly radioactive, it can be used to study the behavior of atoms and molecules in extreme conditions.

Significance of the Discoveries

The discoveries of radium and protactinium were significant for several reasons. They helped to fill in gaps in the periodic table and provided scientists with more information about the properties of radioactive elements. They also led to the development of new technologies, such as cancer treatments and nuclear power.

Conclusion: Impact on Science and Technology

The discoveries of radium and protactinium were important milestones in the history of chemistry and physics. They expanded our understanding of the nature of matter and paved the way for new technologies. Today, we continue to study these elements and their properties, with the hope of unlocking even more secrets about the world around us.

References and Further Reading

• "Radium." Los Alamos National Laboratory. https://periodic.lanl.gov/88.shtml
• "Protactinium." Los Alamos National Laboratory. https://periodic.lanl.gov/91.shtml
• "Marie Curie." Nobel Prize. https://www.nobelprize.org/prizes/physics/1903/marie-curie/biographical/
• "Frederick Soddy." Nobel Prize. https://www.nobelprize.org/prizes/chemistry/1921/soddy/biographical/