This series uses demonstrations and animations to take students on a journey of discovery to explain what we know about atoms-and how we know what we know about atoms. The sixth episode examines the qualities of the electron shell, and the experiments that lead to its discovery. By explaining the basics of atoms, students can better understand the chemical reactions which led to their discovery. It also looks at the arrangement of the periodic table, spectroscopes, and atom size.

Originally released by Liacos Educational Media, 2015. Streaming video file encoded with permission for digital streaming by Infobase on September 26, 2015. Link to website with Teacher's notes and Question Sheet for students available under Additional info tag.

Electron Shells --(2:44) -- Atom Sheds Light -- (5:15) -- Atom Sheds Light, Part 2 -- (1:39) -- Bohr Atom -- (5:12) -- Electron Configurations -- (5:47) -- Electron Configurations, Part 2 -- (3:08) -- Size of Atoms -- (5:19) -- Bonus Feature 1: Ever-Changing Periodic Table -- (3:33) -- Bonus Feature 2: Flame Tests: The Easy Way For Students -- (1:46) -- Ooh, atoms -- (1:48) -- Electronic Shells: Shredding Light on Atoms, Episode 6 -- (2:00). Part A: Introduction: Atoms are made of a nucleus of protons and neutrons which is surrounded by orbiting electrons. The electrons occupy only certain fixed energy levels called electron shells. Part B: The Atom Sheds Light: The discovery of electrons shells can be traced back to the discovery that elements which are in a hot gaseous state glow with a specific range of colours which is unique to each element. We demonstrate the use of flame tests and spectroscopes and explain how they were used to discover new elements. Part C: The Discovery of Electron Shells: By analysing the light emitted by atoms and by firing X-rays at various crystals, scientists in the 1910s discovered that electrons don’t orbit randomly around the nucleus (like planets orbit the sun), but orbit only in electron shells with a specific range of energies. Part D: Electron Configurations: Electrons occupy electron shells. Each shell that surrounds the nucleus can hold only a certain number of electrons. The Periodic Table organises the elements into Groups and Periods (columns and rows) based largely on how the electrons are arranged in each element’s electron shells. Part E: The Size of Atoms: The size of an atom is determined by how spread out the electrons are. We demonstrate using a solid steel sphere how small atoms actually are.