Writing Ionic Compounds The “Swap & Drop” Method

Why do atoms form ions? All atoms want to gain stability. We need to look at the valence electrons of each atom. Valence Electrons: Electrons in the outermost energy level. All atoms want to get to eight valence electrons to become stable. “8 is Great!!!”

+1 ion LOSE 1 ELECTRON! Look at Group 1! All group 1 elements have 1 valence electron. Is it easier for them to lose 1 electron, or try to gain 7 electrons? LOSE 1 ELECTRON! +1 ion

+2 ion LOSE 2 ELECTRONS! Look at Group 2! All group 2 elements have 2 valence electron. Is it easier for them to lose 2 electrons, or try to gain 6 electrons? LOSE 2 ELECTRONS! +2 ion

+3 ion LOSE 3 ELECTRONS! Look at Group 3! All group 3 elements have 3 valence electron. Is it easier for them to lose 3 electrons, or try to gain 5 electrons? LOSE 3 ELECTRONS! +3 ion

+4 ion LOSE 4 ELECTRONS! Look at Group 4! All group 4 elements have 4 valence electron. Because 4 is in the middle, we usually just call all Group 4 Ions +4 LOSE 4 ELECTRONS! +4 ion

-3 ion GAIN 3 ELECTRONS! Look at Group 5! All group 5 elements have 5 valence electron. Is it easier for them to lose 5 electrons, or try to gain 3 electrons? GAIN 3 ELECTRONS! -3 ion

-2 ion GAIN 2 ELECTRONS! Look at Group 6! All group 6 elements have 6 valence electrons. Is it easier for them to lose 6 electrons, or try to gain 2 electrons? GAIN 2 ELECTRONS! -2 ion

-1 ion GAIN 1 ELECTRON! Look at Group 7! All group 7 elements have 7 valence electrons. Is it easier for them to lose 7 electrons, or try to gain 1 electron? GAIN 1 ELECTRON! -1 ion

8 is GREAT!!! No Ions Needed!!! Look at Group 8! All group 8 elements have 8 valence electrons. 8 is GREAT!!! No Ions Needed!!!

K Cl - + 1 1 Swap & Drop Method For Ionic Compounds Only! Potassium Ion K Chlorine Ion Cl - + 1 1 Step 1: Drop the signs.

K Cl 1 1 Swap & Drop Method Step 2: Swap Values. Potassium Ion Chlorine Ion Cl 1 1 Step 2: Swap Values.

K Cl 1 1 1 1 Swap & Drop Method Step 3: Drop Values to Subscripts. Potassium Ion K Chlorine Ion Cl 1 1 1 1 Step 3: Drop Values to Subscripts.

Swap & Drop Method Potassium Ion K Chlorine Ion Cl Potassium Chloride Step 4: When the values are the same, then they can be erased. The number (1) is never required.

Al O - + 3 2 Swap & Drop Method Step 1: Drop the signs. Aluminum Ion Oxygen Ion O - + 3 2 Step 1: Drop the signs.

Al O 3 2 Swap & Drop Method Step 2: Swap Values. Aluminum Ion Oxygen Ion O 3 2 Step 2: Swap Values.

Al O 2 3 2 3 Swap & Drop Method Step 3: Drop values to subscripts. Aluminum Ion Al Oxygen Ion O 2 3 2 3 Step 3: Drop values to subscripts.

Al O 2 3 Swap & Drop Method Step 4: Combine into compound. Aluminum Ion Al Oxygen Ion O 2 3 Aluminum Oxide Step 4: Combine into compound.