Discovering the Electron, Proton and Neutron

Teach the modeling sheets first, since later pages expect students to know valence electrons. Save the nucleus and radiation pages for the end of the unit.

Place the discoveries of the electron, proton and neutron on a timeline, from Thomson to Chadwick. The directions on the page read: Read the text. Write each discovery in its box on the timeline. An answer key is included.

Yes, both. We made it for 8th grade matter, and it works the same at home or at school. At home, a student can work through it alone and then go over it with you, which shows quickly what is solid and what needs another look. In class it works as independent practice, homework or a warm-up, and you can print one copy or a full set.

A molecule is a small, separate group of bonded atoms, like H2O. An extended structure has no separate molecules, and its atoms or ions link into one huge repeating network, like diamond or salt. Simple Molecules Versus Extended Structures classifies six models.

Find the number of valence electrons from the group, then place one dot on each side of the symbol before pairing them. Oxygen, in group 16, gets six dots. Valence Electrons and Lewis Dot Diagrams practices periods 2 and 3.

Half life is the time it takes for half of the atoms in a sample of an unstable isotope to decay. After two half lives, 25 percent of the original atoms remain. Unstable Nuclei and Half Life Guided Notes explains this with a graph.