Catalyst 1/6/11How many valence electrons do the following atoms have?SulfurFluorineCalciumAluminum

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)

– 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.

P3-

Ga3-

In3-

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

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

Other common ions

• Ag+

• Zn2+

• Fe2+

• Fe3+

• Cu2+

• Cu+

• Pb+

• Pb2+

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

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?