1. The Periodic table

2. Periodic Table Elements are classified by their weight and how they react.

3. Periodic Table An element is written with information about its number of protons and neutrons. Calcium is number 20. It is written: Ca 20 40 Mass number = protons + neutrons Atomic number = protons Symbol

4. Periodic Table The elements are arranged in order of mass and structure into a table known as the periodic table:

5. Periodic Table The main columns are called the groups: Group 1 Group 2 Group 3Group 4Group 5 Group 6Group 7 Group 8

6. Periodic Table The main rows are called the periods: 1 st period 2 nd period 3 rd period 4 th period 5 th period 6 th period 7 th period

7. Periodic Table The group represents the number of valence electrons Oxygen has 6 valence electrons and is in group 6 Group 6 Sodium has 1 valence electron and is in group 1 Group 1

8. Periodic Table The group represents the number of valence electrons Neon has 8 valence electrons and is in group 8 Group 8 Tin has 4 valence electrons and is in group 4 Group 4

9. Periodic Table The periods represents the number of electron shells Oxygen has 2 electron shells and is in the 2 nd period 2 nd period Sodium has 3 electron shells and is in the 3 rd period 3 rd period

10. Periodic Table The group represents the number of valence electrons Neon has 2 electron shells and is in the 2 nd period 2 nd period Tin has 5 electron shells and is in the 5 th period 5 th period