electron dot structure also called lewis dot structure

Electron Dot StructureElectron Dot Structure

also called Lewis Dot Structurealso called Lewis Dot Structure

Arranging the dots…Arranging the dots…

Dots are placed around a symbol to Dots are placed around a symbol to indicate the number of valence eindicate the number of valence e--

How many dots may be present?How many dots may be present?

Duet or Octet Rule?Duet or Octet Rule?


Dots are used to indicate covalent Dots are used to indicate covalent bonding.bonding.

For what type of element will we be For what type of element will we be drawing electron dot structures?drawing electron dot structures?

What types of compounds will be What types of compounds will be illustrated?illustrated?


X X 1

2

3

4 8

6

57

Dots can be rearranged toDots can be rearranged to

accommodate bonding illustration.accommodate bonding illustration.

Arranging the dots for an atom…Arranging the dots for an atom…

H Cl

Arranging the dots for a molecule…Arranging the dots for a molecule…

H Cl

H Cl

Arranging the dots Arranging the dots and linesand lines for a for a molecule…molecule…

H Cl

Replace bonding pairs with a line,but always show the lone pairs of electrons.

Notice that each atom is obeying its proper rule…duet or octet…

upon completion of the dot structure.

Arranging the dots for water…Arranging the dots for water…

H O

H

Final structure for water…Final structure for water…

H O

H

Arranging the dots forArranging the dots forcarbon dioxide…carbon dioxide…

C O

O

Arranging the dots forArranging the dots forcarbon dioxide…carbon dioxide…

C OO

Final structure forFinal structure forcarbon dioxide…carbon dioxide…

C OO

Arranging the dots forArranging the dots forcarbon monoxide…carbon monoxide…

C O


C OHow many electrons does the oxygen

have around it?...the carbon?

Since O is happy, and C is not, we moveelectrons around to keep everyone happy.


C OThis is a coordinate covalent bond—it is made when one atom contributesboth electrons to a covalent bond.

Final structure forFinal structure forcarbon monoxide…carbon monoxide…

C O

Avoiding the trickiness…Avoiding the trickiness…

The Kelter Method of drawing electron dot The Kelter Method of drawing electron dot structuresstructures saves a lot of griefsaves a lot of grief enables the successful drawing of electron enables the successful drawing of electron

dot structures without the hassle of figuring dot structures without the hassle of figuring out which electrons go whereout which electrons go where

has exceptions, but they are logicalhas exceptions, but they are logical

The Kelter MethodThe Kelter Method

Determine the number of Determine the number of happyhappy e e-- in the in the entire molecule or ion.entire molecule or ion. Happy electron number depends upon Happy electron number depends upon

whether the atom obeys the duet or octet rulewhether the atom obeys the duet or octet rule

Determine the number of Determine the number of ownedowned e e-- in the in the entire molecule or ion.entire molecule or ion. Owned electron number depends upon the Owned electron number depends upon the

number of valence electrons that the atom number of valence electrons that the atom hashas


Subtract the number of owned eSubtract the number of owned e-- from the from the number of happy enumber of happy e-- and divide that and divide that difference by two…this will equal the difference by two…this will equal the number of bonds in the molecule or ion.number of bonds in the molecule or ion.

#happy e#happy e-- - #owned e - #owned e-- = #bonds = #bonds

22


Place the appropriate number of bonds Place the appropriate number of bonds around the central atom.around the central atom. Central atom is the one that occurs one time Central atom is the one that occurs one time

in the molecule or ion. It is usually carbon if in the molecule or ion. It is usually carbon if carbon is present.carbon is present.

Attach the perimeter atoms and make Attach the perimeter atoms and make them all happy (obey the appropriate rule) them all happy (obey the appropriate rule) by placing electron dots around them.by placing electron dots around them.


Account for all of the owned eAccount for all of the owned e-- that you that you originally indicated, and add any leftovers originally indicated, and add any leftovers to the central atom.to the central atom.

If you are dealing with a polyatomic ion, If you are dealing with a polyatomic ion, place brackets around the formula and put place brackets around the formula and put the charge outside of the brackets.the charge outside of the brackets.


Multiple bonds will be blatantly indicated Multiple bonds will be blatantly indicated by the Kelter Method.by the Kelter Method. If the Kelter Method tells you that you need If the Kelter Method tells you that you need

more bonds than you think you can possibly more bonds than you think you can possibly have in the molecule or ion, then there will be have in the molecule or ion, then there will be at least one multiple (double or triple) bond in at least one multiple (double or triple) bond in the molecule or ion.the molecule or ion.


Exceptions to the method will be Exceptions to the method will be exceptions to the duet or octet rule…that exceptions to the duet or octet rule…that is, holding more than 2 or more than 8 eis, holding more than 2 or more than 8 e-- around a central atom.around a central atom. If the Kelter Method tells you that you need If the Kelter Method tells you that you need

fewer bonds than you know you can have in fewer bonds than you know you can have in the molecule or ion, then it will be an the molecule or ion, then it will be an exceptional situation.exceptional situation.

The Kelter Method…HThe Kelter Method…H22OO

#happy e#happy e-- = = Each H wants how many to be happy?Each H wants how many to be happy? The O wants how many to be happy?The O wants how many to be happy?

#owned e#owned e-- = = Each H already owns how many?Each H already owns how many? The O already owns how many?The O already owns how many?

1228

81

6

12 – 8 = 2 bonds 2


Oxygen is the central atom…it only Oxygen is the central atom…it only appears one time.appears one time.

O

Place two bonds around the central atomas indicated by the Kelter Method


Attach the perimeter atoms…in this case Attach the perimeter atoms…in this case the two hydrogen atoms.the two hydrogen atoms.

OMake the perimeter atoms happy...

Each hydrogen atom wants two electrons, and They already have two electrons…

no dots need to be added

HH


Account for all of the owned electrons by Account for all of the owned electrons by adding electrons to the central atom.adding electrons to the central atom.

OThere were 8 owned electrons in this molecule…Four are accounted for with the bonding lines…

Add the other 4 electrons around the central atom.

HH

The Kelter Method…COThe Kelter Method…CO22

#happy e#happy e-- = = The C wants how many to be happy?The C wants how many to be happy? Each O wants how many to be happy?Each O wants how many to be happy?

#owned e#owned e-- = = The C already owns how many?The C already owns how many? Each O already owns how many?Each O already owns how many?

2488

1646

24 – 16 = 4 bonds 2


Carbon is the central atom…it only Carbon is the central atom…it only appears one time.appears one time.

C

Place four bonds around the central atomas indicated by the Kelter Method


Attach the perimeter atoms…in this case Attach the perimeter atoms…in this case the two oxygen atoms.the two oxygen atoms.

CMake the perimeter atoms happy...

Each oxygen atom wants 8 electrons, and they already have 4 electrons…

4 dots need to be added to each oxygen

OO


Account for all of the owned electrons by Account for all of the owned electrons by adding electrons to the central atom.adding electrons to the central atom.

There were 16 owned electrons in this molecule…All 16 are accounted for with the bonding linesand dots around the O’s…and all are happy.

C OO

The Kelter Method…COThe Kelter Method…CO

#happy e#happy e-- = = The C wants how many to be happy?The C wants how many to be happy? The O wants how many to be happy?The O wants how many to be happy?

#owned e#owned e-- = = The C already owns how many?The C already owns how many? The O already owns how many?The O already owns how many?

1688

1046

16 – 10 = 3 bonds 2

The Kelter Method…COThe Kelter Method…CO

There is no true central atom since there There is no true central atom since there are only two atoms.are only two atoms.

C

Place three bonds next to the C atomas indicated by the Kelter Method


Attach the O atom.Attach the O atom.

Make each atom happy...Each atom wants8 electrons, and they already have 6 electrons…

2 dots need to be added to each atom…Account for all owned electrons.

OC

The Kelter Method…OHThe Kelter Method…OH1-1-

#happy e#happy e-- = = The O wants how many to be happy?The O wants how many to be happy? The H wants how many to be happy?The H wants how many to be happy?

#owned e#owned e-- = = The O already owns how many?The O already owns how many? The H already owns how many?The H already owns how many? And the 1- charge tells you?And the 1- charge tells you?

1082

861

10 – 8 = 1 bond 2

1 more e- is owned


There is no true central atom since there There is no true central atom since there are only two atoms.are only two atoms.

O

Place one bond next to the O atomas indicated by the Kelter Method


Attach the H atom.Attach the H atom.

Make each atom happy...The O wants 8 e-, and the H wants 2 e-…The O and the H already

have 2 e-…6 dots need to be added to the O atomAccount for all owned electrons.

HO


Add brackets around the ion.Add brackets around the ion.

Place the charge of the ion outsideof the brackets.

HO1-


So, where did the extra electron So, where did the extra electron originate?originate?

Maybe a sodium atom was strolling by…anddonated an electron to the cause.

HO1-

Na Na1+

The Kelter Method…COThe Kelter Method…CO332-2-

#happy e#happy e-- = = The C wants how many to be happy?The C wants how many to be happy? Each O wants how many to be happy?Each O wants how many to be happy?

#owned e#owned e-- = = The C already owns how many?The C already owns how many? Each O already owns how many?Each O already owns how many? And the 2- charge tells you?And the 2- charge tells you?

3288

2446

32 – 24 = 4 bonds 2

2 more e- are owned


Carbon is the central atom…it only Carbon is the central atom…it only appears one time.appears one time.

Place four bonds around the central atom as indicated bythe Kelter Method, but you only have 3 perimeter atoms…

C


Attach the O atoms.Attach the O atoms.

Make each O atom happy with 8 e-. Two O atoms alreadyhave 2 e- and one O atom has 4 e- …6 dots need to beadded to two O atoms and 4 dots need to be added to

one O atom. Account for all owned electrons.

COO

O


Add brackets around the ion.Add brackets around the ion.

Place the charge of the ion outsideof the brackets.

COO

O

2-

The Kelter Method…BIThe Kelter Method…BI33

#happy e#happy e-- = = The B wants how many to be happy?The B wants how many to be happy? Each I wants how many to be happy?Each I wants how many to be happy?

#owned e#owned e-- = = The B already owns how many?The B already owns how many? The I already owns how many?The I already owns how many?

2628

2437

26 – 24 = 1 bond 2


Boron is the central atom…there is no way Boron is the central atom…there is no way only one bond can accommodate 3 I’s! only one bond can accommodate 3 I’s! So, override the Kelter MethodSo, override the Kelter Method

Place the number of bonds around the central atom thatwill take care of all of the perimeter atoms…

B


Attach the perimeter I atoms.Attach the perimeter I atoms.

Make each I atom happy with 8 e-. Each I atom alreadyhas 2 e- …6 dots need to be added to each I atom

BI I

I

Now, practice bunchesNow, practice bunches

Draw the electron dot structures of each Draw the electron dot structures of each molecule or ion on the practice sheet on a molecule or ion on the practice sheet on a separate sheet of paper in your notebook.separate sheet of paper in your notebook.

Take your time with it.Take your time with it.

Use the Kelter Method to help you.Use the Kelter Method to help you.

electron dot structure also called lewis dot structure

Documents

dots dots

electron dots

logical slide

atom hcl slide

carbon dioxide c o o

carbon monoxide c o

water h o h slide

owned electron number