Problem 117 - Chemistry The Molecular Science

Question

Prior to 1734 , only 14 elements were known. The rest of the known elements have been discovered across the next nearly three centuries. From \(1805-1825,12\) new elements were discovered. A cluster of six new elements was isolated and identified from \(1895-1905 .\) Beginning in 1940 to the present, 19 new elements have been characterized. During each of these periods of discovery, a single scientific discovery or breakthrough led to the discovery of the new elements. Use the Internet to determine what each of the discoveries was and how it led to the discovery of new elements.

Step-by-Step Solution

Answer

Atomic theory, radioactivity, and nuclear reactions facilitated these discoveries.

Step 1: Analyze the Time Period 1805-1825

During the years 1805 to 1825, there was significant advancement in the field of chemistry, particularly the development of atomic theory by John Dalton. This new understanding of atomic weights and valency helped chemists to identify and isolate new elements. Additionally, improvements in laboratory techniques such as electrochemistry, pioneered by scientists like Davy and Berzelius, enhanced the capability to discover elements not previously isolated.

Step 2: Examine the Period 1895-1905

In the period between 1895 and 1905, the discovery of radioactivity played a major role in the discovery of new elements. Scientists like Marie Curie discovered radioactive elements like polonium and radium. The understanding of radioactive decay led to the identification of other elements emerging from decay series, greatly expanding our knowledge of the elements.

Step 3: Investigate the Period 1940-Present

Starting from 1940, the use of nuclear reactors and particle accelerators became the core technology for synthesizing new elements. This period marked the beginning of the creation of transuranium elements (elements beyond uranium on the periodic table) by scientists such as Glenn T. Seaborg and his team. They used particle accelerators to bombard atomic nuclei which resulted in the creation of entirely new elements.

Key Concepts

Atomic Theory

Atomic theory transformed the way scientists understood the composition of matter. In its early development during the early 1800s, John Dalton introduced the idea that all matter is composed of atoms. These atoms, unique to each element, combine in fixed ratios to form compounds. Dalton's atomic theory included several key postulates:

• Matter is made up of small, indivisible particles known as atoms.
• Atoms of a given element are identical in mass and properties.
• Compounds are formed by the combination of atoms of different elements.
• A chemical reaction is a rearrangement of atoms.

Dalton's work laid the groundwork for future discoveries and was crucial in developing the periodic table. It also influenced later discoveries in chemistry, as understanding atomic weights and valencies became a fundamental part of identifying and isolating new elements.

Radioactivity

Radioactivity, discovered in the late 19th century, significantly advanced our understanding of the atomic nucleus. Henri Becquerel first observed radioactivity in 1896, followed by extensive research by Marie and Pierre Curie. The Curies discovered radioactive elements like polonium and radium, furthering the study of radioactivity.

• Radioactivity involves the spontaneous emission of particles from unstable atomic nuclei.
• There are three primary types of radioactive decay: alpha, beta, and gamma decay.
• This concept helped scientists identify elements that were products of radioactive decay processes.

Understanding radioactivity had profound implications for science. It not only facilitated the discovery of new elements but also introduced the ability to transmute elements, leading the way to modern nuclear chemistry.

Transuranium Elements

Transuranium elements are elements with atomic numbers greater than uranium (92). These elements do not occur naturally and were first created in laboratories starting in 1940. The creation of transuranium elements marked a pivotal advancement in nuclear physics and chemistry.

• The synthesis of these elements involves bombarding lighter elements with neutrons or other particles in nuclear reactors or particle accelerators.
• Glenn T. Seaborg was a key figure in discovering these elements, including plutonium, americium, and curium.
• These elements are typically highly unstable and radioactive.

The study of transuranium elements has practical applications in medicine, industry, and energy, and continues to be an exciting area of research. They have also expanded our understanding of chemical properties and atomic structure.

Electrochemistry

Electrochemistry is a branch of chemistry that studies the relationship between electricity and chemical reactions. During the early 19th century, this field saw tremendous advances with contributions from scientists like Humphry Davy, who used electricity to isolate pure elements.

• Electrochemistry involves the study of electron transfer between substances.
• It is fundamental to processes like electroplating, electrolysis, and corrosion.
• Key techniques developed in this field have been crucial for discovering new elements, particularly metals.

This area of study has far-reaching applications, helping to drive technological advances in batteries, sensors, and metal purification. Electrochemistry is pivotal in modern technology and continues to be an essential field in scientific research.

Nuclear Reactors

Nuclear reactors are complex devices used to initiate and control nuclear chain reactions. They have become a pivotal tool for synthesizing new elements since World War II. Reactors allow scientists to create elements that cannot be found in nature.

• Nuclear reactors produce a steady stream of neutrons that can bombard atomic nuclei to form new elements.
• This technology was crucial for the discovery of transuranium elements.
• Reactors are also used for energy generation, producing medical isotopes, and conducting research.

The development of nuclear reactors has had profound scientific and industrial implications. They have not only expanded the periodic table but have also contributed to a wide array of applications in different sectors. The continued study of reactors could lead to future breakthroughs in nuclear technology.