2. Mass

3.  Definition: the ~ mass of one atom of an element  Tells us how much one atom weighs in atomic mass units. Mass

4. Ordered by atomic mass. Columns arranged to form groups with similar properties Group/Family Period

5.  Which element has the greatest atomic mass?  Lithium  Sodium  Potassium  Rubidium

6.  The ease and speed with which an element combines, or reacts, with other elements or compounds Pure sodium reacts explosively with air

7. Group 1: metals that react violently with water Group 18: Gases that barely react at all Why do groups/families of elements react the same way?

8.  # of Protons (+) = # of Electrons (-) = 0 charge  Example: Hydrogen  How many electrons does C have?

9.  1 st shell can fit 2 electrons  2 nd and 3 rd shells can fit 8 electrons 2 nd period/row 3 rd period/row 1 st period/row

10.  2 electrons in first shell  8 electrons in 2 nd and 3 rd shells  Examples:

11.  The properties of an element can be predicted from its location on the Periodic Table  This is largely a result of the number of electrons in their outer shell.

12.  How many electrons does an oxygen have?  How many electrons are in its outer shell?  Which group is oxygen most likely to react with?

13. For the first 3 periods: 1) How many electrons are in the outer shell of each element in group 1? Group 2? Group 13? Group 14? Group 15? Group 16? Group 17? Group 18? 2) How many electrons does each element in each group above need to fill its outer shell? 3) Which groups are the most likely to react with one another? 4) Which group is least likely to react with any other group?

14.  For the first 3 periods:  1) How many electrons are in the outer shell of each element in group 1? Group 2?  Group 13? Group 14? Group 15? Group 16? Group 17? Group 18?  2) How many electrons does each element in each group above need to fill its  outer shell?  3) Which groups are the most likely to react with one another?  4) Which group is least likely to react with any other group?