1. 5 th Grade Science Mrs. LaRosa www.middleschoolscience.comwww.middleschoolscience.com 2008 All images are from www.Chem4kids.comwww.Chem4kids.com

2. Periods Each row is called a “period” The elements in each period have the same number of shells or electron energy levels www.chem4kids.com

3. Groups Each column is called a “group” Each element in a group has the same number of electrons in their outer orbital, also known as “shells” or energy levels Except for He, it has 2 electrons The electrons in the outer shell or energy level are called “valence electrons” www.chem4kids.com

4. Transition Metals Transition Metals have slightly different rules for shells and valence electrons. This is something you will learn about in High School Chemistry. www.chem4kids.com

5. Determine the number of shells and the number of valence electrons for: www.chem4kids.com

6. Determine the number of energy levels and the number of valence electrons for: www.chem4kids.com

18. Helium is the exception in Group 8. Since it has just one energy level, that shell can only fit 2 electrons instead of 8. It is in this group because all the elements have a full outer energy level.