WASHINGTON -- Five years of preparation, eight months collecting a few drops of precious radioactive material from a nuclear reactor in Tennessee, five trans-Atlantic flights, millions in research ...

Measurements of an artificial radioactive element called lawrencium could revive an arcane controversy over the element’s position in the periodic table — and the structure of the table itself. An ...

In this video, we explore fundamental concepts about the atom and the forces that govern it. **CHAPTERS** 0:00 - Why is the ...

Note: This video is designed to help the teacher better understand the lesson and is NOT intended to be shown to students. It includes observations and conclusions that students are meant to make on ...

Atoms are very small. They have a radius of around 1 × 10 10 metres. This symbol shows that chlorine has 35 particles in the nucleus (protons and neutrons), 17 of which are protons. It also tells us ...

When the Russian chemist Dmitri Mendeleev published his periodic table of elements in 1869, there were just fifty-nine entries on it. The table grouped those elements—hydrogen, oxygen, and carbon, ...

Wielding proton beams and lasers, physicists have for the first time unlocked one of the key secrets of the rarest naturally occurring element on Earth: astatine. It's so rare that until recently, ...

Use a concept map to review atom-related terms. Concept maps are a way to visually show how the parts of a system relate to one another. In a concept map, nouns are used to describe the components of ...

In 1913, Niels Bohr revised Rutherford's model by suggesting that the electrons orbited the nucleus in different energy levels or at specific distances from the nucleus. By doing this, he was able to ...