Discovery of Radioactive Elements

Lesson Plan - Get It!

Audio:

• Do you know how you got your name?

Take a second to look up the meaning of your name online. Does your family have a different meaning? Elements are given names in a similar way, based on the characteristics of the element or the people discovering them.

Element 106 is named after the scientist who discovered it, Glenn Seaborg. Before learning about Seaborg, you need to know about the work that preceded him.

Radioactivity was described by Marie Curie around 1900. She and her husband, Pierre, discovered two radioactive elements: polonium and radium. They named polonium after the country where Marie was born, Poland.

Radioactive elements were slowly added to the periodic table during the next 30 years, and in the 1930s, the rate of discovery sped up significantly. By this point, physics laboratories had developed advanced technologies to study elemental behavior. The Lawrence Berkeley National Laboratory, located in Berkeley, California, was on the cutting edge of nuclear discovery.

Scientists worked on teams to understand how changing the atomic structure would modify the elements and radioactivity. They started to use technology to create new elements, elements not found in nature. The heaviest element found naturally is uranium, atomic number 92.

One of the first elements created was neptunium, element 93, in 1940. It was synthesized by modifying an atom of uranium using neutrons and positively-charged particles aimed at the nucleus. Plutonium, element 94, was created using the same process during the same year.

Glenn Seaborg was one of the most effective nuclear chemists, contributing to the creation of many synthetic elements. His team described americium, curium, berkelium, and californium.

• Where do you think the names for each of these elements came from?

Jot down a prediction on a sheet for each of the elements listed. You will add a couple more to your list.

All of this work was occurring during the 1940s.

• What world event was also occurring during that time period?

World War Two occurred during this time period, and ended with the nuclear bombs dropped in 1945. While scientists were discovering new radioactive elements, they were also testing new weapons using these elements because they are more powerful.

A new type of bomb driven by hydrogen was tested in 1952. After the explosion, scientists discovered that two new elements had formed during the reaction. They named these elements einsteinium and fermium. Add these two names to your list of predictions!

Scientists continued aiming particles at the nuclei of elements in a lab setting and generating new elements! Mendelevium and nobelium were both discovered using high-tech methods involving adding particles to a smaller atomic nucleus.

• Where do you think these elements got their names from?

Go ahead and add them to the list!

Several elements were discovered by measuring the amount of time it took for the atoms to decay, or by measuring the half-life of the nucleus. Elements identified using this new method included lawrencium, rutherfordium, dubnium, and seaborgium. These names can be added to your list, making a prediction for each element.

There were so many discoveries of nuclear elements during the 1940s and 1950s, but it slowed down as scientists realized that there were only so many ways to modify the atom. The atom can only be so large before it begins to degrade immediately. That is one reason you don't hear about the addition of new elements very often!

The discovery and naming of elements is an important part of the study of chemistry, because many of the names pay homage to scientists who contributed to the understanding of elements and atomic structure.

Review your list of names and predictions, and make sure you have a prediction for each elemental name.

In the Got It? section, you will do some quick research to double-check your predictions and make corrections.