writing ionic compounds the “swap & drop” method

Writing Ionic CompoundsWriting Ionic CompoundsThe “Swap & Drop” MethodThe “Swap & Drop” Method

Why do atoms form ions?Why do atoms form ions?

All atoms want to gain stability.All atoms want to gain stability.

We need to look at the valence electrons We need to look at the valence electrons of each atom.of each atom.

Valence Electrons: Electrons in the Valence Electrons: Electrons in the outermost energy level.outermost energy level.

All atoms want to get to eight valence All atoms want to get to eight valence electrons to become stable.electrons to become stable.

““8 is Great!!!”8 is Great!!!”

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

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

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

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

Look at Group 5!All group 5 elements have 5 valence electron.

GAIN 3 ELECTRONS!

Is it easier for them to lose 5 electrons, or try to gain 3 electrons?

-3 ion

Look at Group 6!All group 6 elements have 6 valence electrons.

GAIN 2 ELECTRONS!

Is it easier for them to lose 6 electrons, or try to gain 2 electrons?

-2 ion

Look at Group 7!All group 7 elements have 7 valence electrons.

GAIN 1 ELECTRON!

Is it easier for them to lose 7 electrons, or try to gain 1 electron?

-1 ion

Look at Group 8!All group 8 elements have 8 valence electrons.

8 is GREAT!!! No Ions Needed!!!

Swap & Drop MethodSwap & Drop Method

Potassium Ion

KChlorine Ion

Cl+ -1 1

Step 1: Drop the signs.

For Ionic Compounds Only!

Swap & Drop MethodSwap & Drop Method

Potassium Ion

KChlorine Ion

Cl1 1

Step 2: Swap Values.

Swap & Drop MethodSwap & Drop Method

Potassium Ion

KChlorine Ion

Cl1 1

Step 3: Drop Values to Subscripts.

1 1

Swap & Drop MethodSwap & Drop MethodPotassium Ion

KChlorine Ion

ClStep 4: When the values are the same, then they can be erased. The number (1) is never required.

Potassium Chloride

Swap & Drop MethodSwap & Drop Method

Aluminum Ion

AlOxygen Ion

O+ -3 2

Step 1: Drop the signs.

Swap & Drop MethodSwap & Drop Method

Step 2: Swap Values.

Aluminum Ion

AlOxygen Ion

O3 2

Swap & Drop MethodSwap & Drop Method

Step 3: Drop values to subscripts.

Aluminum Ion

AlOxygen Ion

O 322 3

Swap & Drop MethodSwap & Drop Method

Step 4: Combine into compound.

Aluminum Ion

AlOxygen Ion

O2 3Aluminum Oxide