1. Catalyst 1/6/11 How many valence electrons do the following atoms have? Sulfur Fluorine Calcium Aluminum Objective: Same as yesterday Homework: Project due tomorrow!!! Write the name, charge, and electron dot diagrams for atoms and ions in columns 1, 2, 15, 16, and 17 up to element 35. (16 elements total)

2. –Cations are positive and are formed by elements on the left side of the periodic chart. –Anions are negative and are formed by elements on the right side of the periodic chart. P 3- Ga 3- In 3-

3. Ion Charges and the Periodic Table The ion that a particular atom will form can be predicted from the periodic table. –Group 1 atoms form cations with 1+ charges –Group 2 atoms form cations with 2+ charges –Most group 13 atoms form cations with 3+ charges –Transition metals form various cations –Group 17 atoms form anions with 1- charges –Group 16 atoms form anions with 2- charges –Most group 15 atoms form anions with 2- charges

4. Why do atoms form ions? Atoms are most stable when they have the same number of electrons as noble gases:8 Elements in columns 1, 2, and 3 must lose electrons and form cations to do this Elements in columns 16 and 17 must gain elections and form anions to do this Noble gases are stable and do not react because they do not want to gain or lose electrons

5. Other common ions Ag + Zn 2+ Fe 2+ Fe 3+ Cu 2+ Cu + Pb + Pb 2+

6. Practice Write the symbol and charge for the following ions: –Magnesium –Sulfide –Iron (II) –Aluminum –Calcium –Helium Write the electron dot diagrams for the atoms and ions of the following ions –Chloride –Sulfide –Magnesium

7. As a group: Write the name, charge, and electron dot diagrams for ions in columns 1, 2, 15, 16, and 17 up to element 35.(16 elements total) What do you notice? Why is this the case?