Section 1: Basic Lewis Structures

Section 1: Basic Lewis Structures
How to Draw Dot Structures for Covalent Bonds

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
--Atoms share VEs to achieve an Octet. --Circle Test for an Octet --Hydrogen only needs two electrons --Carbon is always the central atom (never hydrogen) --Carbon atoms need 4 bonds. --least electronegative atom goes in the center (usually). --Valence electrons to start = finish. --Look for Symmetry in the drawing. --If single bonds don’t work, look for doubles or triples. --Single Bonds --Double Bonds --Triple Bonds --Resonant Structures – Coordinate Bonds

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Hydrogen has 1ve H

H Cl Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Hydrogen has 1ve
Chlorine has 7ves H Cl

Chlorine has 7ves H Cl They share their valence electrons

Chlorine has 7ves Circle Test for Octet H Cl They share their valence electrons

Chlorine has 7ves Circle Test for Octet H Cl Eight Electrons! They share their valence electrons

H Cl Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
Lewis Diagram for HCl H Cl

H Cl H Cl Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
Those two shared electrons represent a single bond and can be written as: H Cl H Cl

H Cl H Cl Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
Those two shared electrons represent a single bond and can be written as: H Cl H Cl The dash represents two electrons in a single bond.

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Hydrogen has 1ve H H

H O H Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Hydrogen has 1ve
Oxygen has 6ves H O H

Oxygen has 6ves H O H They Share their valence electrons

Oxygen has 6ves Octet Test! H O H They Share their valence electrons

H O H Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
The dashes represents two electrons in a single bond. H O H Water will be bent..

H O H Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
The dashes represents two electrons in a single bond. H O H Hydrogen is never the central atom!!!

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Chlorine has 7ves Cl Cl

Cl Cl Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Chlorine has 7ves
Chlorine is Diatomic Cl Cl

Chlorine is Diatomic Cl Cl Chlorine shares its valence electrons

Chlorine is Diatomic Octet Test! Cl Cl Chlorine shares its valence electrons

Cl Cl Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
The dash represents two electrons in a single bond. Cl Cl

Cl Cl Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
The dash represents two electrons in a single bond. Cl Cl All the Halogens behave like this!!!!

F F Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
The dash represents two electrons in a single bond. F F All the Halogens behave like this!!!!

F F Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
This is why the Halogens are Diatomic! F F All the Halogens behave like this!!!!

I I Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
This is why the Halogens are Diatomic! I I All the Halogens behave like this!!!!

Br Br Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
Bromine is a dark Red Liquid! Br Br All the Halogens behave like this!!!!

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Nitrogen has 5ves N

H N H H Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Nitrogen has 5ves
Hydrogen has 1ve H N H H

Hydrogen and Nitrogen share their valence electrons Hydrogen has 1ve H N H H

Hydrogen and Nitrogen share their valence electrons Hydrogen has 1ve H N H H Octet Test!

H N H H Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
The dashes represents two electrons in a single bond. H N H H

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Carbon has 4ves

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Carbon has 4ves C

F F C F F Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Carbon has 4ves
Fluorine has 7ves F C F F

Fluorine has 7ves F F C F F

Fluorine has 7ves F Octet Test! F C F F

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 F F C F F

Assignment: H2 CCl4 CH4 NF3 H2S
The Next three bonds listed involve double and triple bonds and will be covered in the next video. Draw Covalent Lewis Dot Structures for the molecules on the left. Hydrogen Sulfide Carbon Tetrachloride Methane Nitrogen TriFluoride

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Oxygen Has 6ves O O

O O Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Oxygen Has 6ves
Octet Test??? O O

O O Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Oxygen Has 6ves
Octet Test??? O O Only 7 electrons not 8!

O O Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
We have to use a DOUBLE BOND O O

We have to use a DOUBLE BOND Octet Test O O

We have to use a DOUBLE BOND Each dash represents a bond of two shared electrons. O O

We have to use a DOUBLE BOND We usually pair off the unbonded electrons. O O

Oxygen has 6 valence electrons. O O

O C O Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
Oxygen has 6 valence electrons. Carbon has 4 O C O

Joining them in a single bond fails the octet test for all three atoms. O C O

Joining them in a single bond fails the octet test for all three atoms. O C O So we have to use a double bond.

So we have to use a double bond.

They Join and All Atoms pass the Octet Test.

We Represent these two double bonds like this.

Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2 Nitrogen has 5 Ves. N N

N N Covalent Bonds HCl H20 Cl2 NH3 CF4 O2 CO2 N2
A Single Bond Fails the Octet test. N N

What about a Double Bond? N N

A Double Bond Fails the Octet Test N N

Nitrogen Requires a Triple Bond! N N

This Passes the Octet Test! N N

A Triple Bond! Each Dash represents 2 electrons N N

Another Way to do this: Each Nitrogen has 5 Ves for 10 electrons total Start with a Single Bond representing 2 electrons N N

Another Way to do this: Each Nitrogen has 5 VEs for 10 electrons total Start with a Single Bond representing 2 electrons Fill in the next 8 electrons … N N

Another Way to do this: Each Nitrogen has 5 VEs for 10 electrons total Start with a Single Bond representing 2 electrons Fill in the next 8 electrons … Move Electrons into bonds until you have an octet. N N

Another Way to do this: Each Nitrogen has 5 Ves for 10 electrons total Start with a Single Bond representing 2 electrons Fill in the next 8 electrons … Move Electrons into bonds until you have an octet. N N

F F O O N N Bond Strength Weakest Strongest
Think of each bond (dash) as a rubber band holding the atoms together. Two rubber bands is stronger than one but three is stronger than two. Nitrogen (N2) makes up 78% of our atmosphere and is a really stable and inert molecule O O But two single bonds is stronger than a double bond… N N Strongest Double not 2x single

BOND TYPE BASED ON ELECTRONEGATIVITY

Two types of Covalent Bonds
Non-Polar Covalent Polar-Covalent Electrons Shared Equally: --all diatomic molecules Electrons Shared Unequally --due to electronegativity δ Small Delta indicates PARTIAL CHARGES There is a small degree of sharing and orbital overlap even in ionic bonds.

AlCl3 Aluminum Chloride
WHAT TYPE OF BOND DO ALUMINUM AND CHLORINE FORM? Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding)

AlCl3 Aluminum Chloride
WHAT TYPE Of BOND DO ALUMINUM AND CHLORINE FORM? Ionic: Metal and NonMetal Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding)

AlCl3 Aluminum Chloride COVALENT BOND
WHAT TYPE Of BOND DO ALUMINUM AND CHLORINE FORM? Ionic: Metal and NonMetal COVALENT BOND Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding)

Confused? To muddy waters even further, there is no such thing as a purely ionic or covalent bond. AlCl3 Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding)

Electronegativity - +11 A measure of an atom or group of atom’s tendency to attract electrons Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding)

As you go down a group Electronegativity decreases.
Additional Electron shielding and increased distance from the nucleus makes adding a new electron more difficult Increasing nuclear charge (pull) without any additional shielding makes makes adding an electron easier. Water sugar salt We are going to talk about bonding Bonding between atoms is CIM Why do 2h and OThere are several difference bond types in Chemistry. All are concerned with electrons. Intermolecular bonds occur between molecules (hydrogen bonding) As you go across a period Electronegativity increases.

Electronegativity (χ) is a “rule of thumb” Bond type is ∝ to Δχ

Δ Electronegativity ELECTRON TUG OF WAR!

Electron Tug of War H-H Hydrogen 2.20 H-F Fluorine 3.98

Electronegativity Sliding Bond Scale
Δχ Bond Type Example Non-Polar Covalent H2 ≥0.5 to >1 Polar Covalent HCl ≥1 to <2 Very Polar Covalent HF ≥2 Ionic Bond Na+Cl- Electronegativity Sliding Bond Scale Electron Tug of War NaCl H2O CO2

Ionic Bond (Extremely Polar)
Practice Problems What type of bond will form between the following atoms? N and H F and F Ca and Cl Al and Cl H and Br K and Cl C and O Cl and F Li and O H and O Δ Electronegativity Bond Type Non-Polar Covalent ≥0.5 to >1 Polar Covalent ≥1 to <2 Very Polar Covalent ≥2 Ionic Bond (Extremely Polar)

Practice Problems H—CL H—Br H—S H—C Answer: C and D tie to B to A
What type of bond will form between the following atoms? Place these covalent bonds in order of least to most polar. N (3) and H (2.1) = 0.9 mod PC F (4) and F(4) = 0 = non-polar Ca (1) and Cl (3) = 2 = Ionic Al (1.5) and Cl (3) = 1.5 = very PC H and Br mod PC K and Cl ionic C and O mod to very PC Cl and F mod to very PC Li and O ionic H and O polar (thisH20!) H—CL H—Br H—S H—C Answer: C and D tie to B to A

Naming Molecular (Covalent) Compounds
Number Prefix 1 mono 2 di- 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca These are needed because Nitrogen and Oxygen can combine in a number of different ways. N20 NO NO2 N2O4 N2O5

Number Prefix 1 mono 2 di- 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca First word is the name of the element appearing first in a chemical formula, including a prefix indicating how many atoms of that element are present if more than one. Second word ends in ide and also has a prefix indicating the number of atoms present.

Nitrogen and Oxygen N20 = Dinitrogen monoxide NO =Nitrogen Monoxide
NO2 Nitrogen Dioxide N2O4 Dinitrogen Tetraoxide N2O5 Dinitrogen Pentaoxide

Number Prefix 1 mono 2 di- 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca CO = S02 = NO3 = CF5 = CO2 = NO2 = Nitrogen Monoxide = Dinitrogen trioxide = Carbon Tetrafluoride = Dinitrogen pentoxide = Silicon TetraChloride = Disilicon Hexachloride = NO is also nitrous oxide

Number Prefix 1 mono 2 di- 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca CO =Carbon Monoxide S02 = Sulfur Dioxide NO3 = Nitrogen trioxide CF5 =Carbon Pentafluoride CO2 = Carbon Dioxide NO2 = Nitrogen Dioxide NO = Nitrogen Monoxide N2O3 =Dinitrogen trioxide CF4 =Carbon Tetrafluoride N2O5=Dinitrogen pentoxide SiCl4 = Silicon TetraChloride Si2Cl6 = Disilicon Hexachloride NO is also nitrous oxide

Which of the following compounds is named INCORRECTLY?
CS2, carbon disulfide BCl3, boron trichloride IF7, iodine heptafluoride PCl5, phosphorus hexachloride d

Which of the following molecular compounds is named INCORRECTLY?
SbCl3, antimony trichloride C2O5, dicarbon pentoxide CF4, carbon tetrafluoride H3As, hydrogen arsenide d

Formal Charge: FC = V – (N + B/2) H2O CO2 NH3 [NO3]- Acetylense C2H2

Formal Charge: H2O CO2 NH3 [NO3]- Oxygen FC: 6 – (4+2) = 0
Hydrogens FC: 1 – (0+1) = 0 Acetylense C2H2

Formal Charge: H2O CO2 NH3 [NO3]- Acetylense C2H2

Formal Charge: H2O CO2 NH3 [NO3]- Oxygens FC: 6 – (4+2) = 0
Carbon FC: 4 – (0+4) = 0 Acetylense C2H2

Formal Charge: H2O CO2 NH3 [NO3]- Hydrogen FC: 1 – (0+1) = 0
Acetylense C2H2 Hydrogen FC: – (0+1) = 0 Nitrogen FC: – (2+3) = 0

Formal Charge: H2O CO2 NH3 [NO3]- Oxygen Top FC: 6 – (4+2) = 0
Acetylense C2H2 Oxygen Top FC: – (4+2) = 0 Oxygens on Bottom FC: – (6+1) = -1 Nitrogen FC: – (0+4) = +1

Assignment: H2CO [CN]- [ClO3]-
Draw the Lewis Dot Structure then determine the formal charge for each atom in the molecule. METHANAL FORMALDEHYDE

FC & Octet Rule H2SO4 SO3 SO2 Acetylense C2H2 Octet Rule is just a RULE OF THUMB, not a law of Chemistry Lewis Structures are Limited 2D drawings. Molecular Orbital Theory is more robust

FC & Octet Rule H2SO4 SO3 SO2 Acetylense C2H2

FC & Octet Rule H2SO4 SO3 SO2 Acetylense C2H2 Octet Rule works great for C, N, O, F and Halogens but Once you get to row/energy level 3 on the periodic table you get D shells and the Octet rule doesn’t necessarily apply.

FC & Octet Rule H2SO4 SO3 SO2 Compare the Formal Charge
Acetylense C2H2

FC & Octet Rule H2SO4 SO3 SO2 Compare the Formal Charge Sulfur:
Acetylense C2H2 Sulfur: Hydrogen-L Hydrogen-R Oxygen-L Oxygen-R Oxygen-T Oxygen-B Sulfur: Hydrogen-L Hydrogen-R Oxygen-L Oxygen-R Oxygen-T Oxygen-B

Acetylense C2H2 Sulfur: – (0 +4) = +2 Hydrogen-L Hydrogen-R Oxygen-L Oxygen-R Oxygen-T Oxygen-B Sulfur: (0 + 6) = 0 Hydrogen-L Hydrogen-R Oxygen-L Oxygen-R Oxygen-T Oxygen-B

Acetylense C2H2 Sulfur: – (0 +4) = +2 Hydrogen-L – (0+1) = 0 Hydrogen-R – (0+1) = 0 Oxygen-L Oxygen-R Oxygen-T Oxygen-B Sulfur: (0 + 6) = 0 Hydrogen-L 1 – (0+1) = 0 Hydrogen-R 1 – (0+1) = 0 Oxygen-L Oxygen-R Oxygen-T Oxygen-B

Acetylense C2H2 Don’t necessarily need to expand octet for sulfuric acid Sulfur: – (0 +4) = +2 Hydrogen-L – (0+1) = 0 Hydrogen-R – (0+1) = 0 Oxygen-L – (4+2) = 0 Oxygen-R – (4+2) = 0 Oxygen-T Oxygen-B Sulfur: (0 + 6) = 0 Hydrogen-L 1 – (0+1) = 0 Hydrogen-R 1 – (0+1) = 0 Oxygen-L – (4+2) = 0 Oxygen-R – (4+2) = 0 Oxygen-T Oxygen-B

Acetylense C2H2 Sulfur: – (0 +4) = +2 Hydrogen-L – (0+1) = 0 Hydrogen-R – (0+1) = 0 Oxygen-L – (4+2) = 0 Oxygen-R – (4+2) = 0 Oxygen-T – (6+1) = -1 Oxygen-B – (6+1) = -1 Sulfur: (0 + 6) = 0 Hydrogen-L 1 – (0+1) = 0 Hydrogen-R 1 – (0+1) = 0 Oxygen-L – (4+2) = 0 Oxygen-R – (4+2) = 0 Oxygen-T Oxygen-B

Acetylense C2H2 Sulfur: – (0 +4) = +2 Hydrogen-L – (0+1) = 0 Hydrogen-R – (0+1) = 0 Oxygen-L – (4+2) = 0 Oxygen-R – (4+2) = 0 Oxygen-T – (6+1) = -1 Oxygen-B – (6+1) = -1 Sulfur: (0 + 6) = 0 Hydrogen-L 1 – (0+1) = 0 Hydrogen-R 1 – (0+1) = 0 Oxygen-L – (4+2) = 0 Oxygen-R – (4+2) = 0 Oxygen-T – (4+2) = 0 Oxygen-B – (4+2) = 0

Assignment/Quiz SO3 SO2 [SO4]2- SF6
Draw the preferred dot structure for the molecules on the right, indicate any octet violations and include calculations of formal charge. Show how the triple bond in Carbon Monoxide (CO) has a coordinate bond in it. Include the formal charge of each atom. In the image below, indicate which dot structure is favorable in terms of formal charge. Acetylense C2H2

[NO3]- [NO3]- Nitrate Ion Another Way to do this:
Count the total number of VEs Start with a Single Bond representing 2 electrons Fill in the next 8 electrons … Move Electrons into bonds until you have an octet. [NO3]-

[NO3]- [NO3]- Nitrate Ion Another Way to do this:
Count the total number of VEs Start with a Single Bond representing 2 electrons Fill in the next 8 electrons … Move Electrons into bonds until you have an octet. [NO3]- 5VEs 18VEs 1VE 24VEs

O O N O [NO3]- [NO3]- Nitrate Ion Another Way to do this:
Count the total number of VEs Start with a Single Bond representing 2 electrons Fill in the rest of the electrons… Move Electrons into bonds until you have an octet. [NO3]- O O 5VEs 18VEs 1VE N 24VEs O

Count the total number of VEs Start with a Single Bond representing 2 electrons Fill in the rest of the electrons… Move Electrons into bonds until you have an octet. [NO3]- O O 5VEs 18VEs 1VE N 24VEs 18VEs Remaining O

Count the total number of VEs Start with a Single Bond representing 2 electrons Fill in the rest of the electrons… Move Electrons into bonds until you have an octet. [NO3]- O O 5VEs 18VEs 1VE N 24VEs 0VEs Remaining O

Count the total number of VEs Start with a Single Bond representing 2 electrons Fill in the rest of the electrons… Move Electrons into bonds until you have an octet. [NO3]- O O 5VEs 18VEs 1VE N 24VEs 18VEs Remaining O 0VEs Remaining Oxygen Obeys the Octet!

Count the total number of VEs Start with a Single Bond representing 2 electrons Fill in the rest of the electrons… Move Electrons into bonds until you have an octet. [NO3]- O O 5VEs 18VEs 1VE N 24VEs 18VEs Remaining O 0VEs Remaining Oxygen Obeys the Octet! But Nitrogen Does not!

Count the total number of VEs Start with a Single Bond representing 2 electrons Fill in the rest of the electrons… Move Electrons into bonds until you have an octet. [NO3]- O O 5VEs 18VEs 1VE N 24VEs 18VEs Remaining O Move a Pair from any Oxygen atom and make one double bond! 0VEs Remaining Oxygen Obeys the Octet! But Nitrogen Does not!

Count the total number of VEs Start with a Single Bond representing 2 electrons Fill in the rest of the electrons… Move Electrons into bonds until you have an octet. [NO3]- O O 5VEs 18VEs 1VE N 24VEs 18VEs Remaining O Move a Pair from any Oxygen atom and make one double bond! 0VEs Remaining Oxygen Obeys the Octet! Nitrogen has an Octet!

Assignment: O3 C2H6 C2H4 CO C2H2 [OH]- [NH4]+
Another Way to do this: Count the Number of VEs Start with a Single Bond representing 2 electrons. Fill in the rest of the electrons making octets where possible… Move Electrons into bonds until you have an octet. Carbon is always the central atom. Carbon will bond to itself. Least electronegative atom in the middle (never H). Some molecules can have a single and double bond. All of these obey the octet rule.

Resonance Structures

Resonance [NO3]- Nitrate Ion
Same Structure Can be drawn in Multiple formats [NO3] Nitrate Ion

O O N O Resonance [NO3]- Nitrate Ion
Same Structure Can be drawn in Multiple formats [NO3] Nitrate Ion O O N O

O N O O Resonance [NO3]- Nitrate Ion
Same Structure Can be drawn in Multiple formats [NO3] Nitrate Ion O N O O

Resonance SO3 Sulfur Trioxide
Same Structure Can be drawn in Multiple formats SO3 Sulfur Trioxide Not the Suflite ion = [SO3]2-

Resonance SO3 Sulfur Trioxide
Same Structure Can be drawn in Multiple formats SO3 Sulfur Trioxide

Resonance [CO3]2- Carbonate
Same Structure Can be drawn in Multiple formats [CO3]2- Carbonate

Resonance [CO3]2- Carbonate
Same Structure Can be drawn in Multiple formats [CO3]2- Carbonate Should Put Brackets

Resonance Same Structure Can be drawn in Multiple formats
We draw all the possible Lewis Structures and use a two-sided arrow to show resonance. The actual molecule is NOT ANY OF the drawn pictures. The actual molecule is a combination of the three images blended together. We know this because the length of double and single bonds differs but in these molecules, the bond lengths are the same (via x-ray diffraction). Single Lewis Structures are Inadequate!

Assignment Draw Resonance Structures for Sulfite (Polyatomic Ion)
Same Structure Can be drawn in Multiple formats Draw Resonance Structures for Sulfite (Polyatomic Ion) Ozone molecule Phosphate Ion (check the FC!)

Coordinate Covalent Bond
One atom contributes both electrons in a bond. Ammonia NH to Ammonium Ion [NH4]+

One atom contributes both electrons in a bond. Ammonia NH to Ammonium Ion [NH4]+ H H N H

One atom contributes both electrons in a bond. Ammonia NH to Ammonium Ion [NH4]+ H+ H H H H N N H H

One atom contributes both electrons in a bond. Ammonia NH to Ammonium Ion [NH4]+ H Nitrogen Contributes Both Electrons! H H H H N N H H

#Valence – (Unshared + ½ Shared)
Compare FC of Nitrogen #Valence – (Unshared + ½ Shared) Ammonia NH to Ammonium Ion [NH4]+ H Nitrogen Contributes Both Electrons! H H H H N N H H

1s orbital is completely empty and it is extremely reactive.
Hydronium Acids and Protonation Hydronium! [H3O]+ H+ H H O Hydrogen Ion! 1s orbital is completely empty and it is extremely reactive.

Compare FC of Nitrogen #Valence – (Unshared + ½ Shared) Hydronium! [H3O]+ H+ H H O The Lone proton (H+ cation) attaches itself to lone pair of valence electrons in the water molecule.

Compare FC of Nitrogen #Valence – (Unshared + ½ Shared) Hydronium! [H3O]+ H Now we have the Hydronium Ion and we need to put in our brackets and charge. H H O

Compare FC of Nitrogen #Valence – (Unshared + ½ Shared) Hydronium! [H3O]+ H Will another hydrogen attach to the other pair forming H40?. H H O

Assignment #Valence – (Unshared + ½ Shared) Formate Ion [HCO2]- Draw a Lewis Dot Structure for the Formate Ion. Draw multiple structures (resonance) if necessary. Include calculations of formal charge. Then Draw the Structure (include resonance if necessary) if a Hydrogen cation (H+) attached to an oxygen and find its name. Include the formal charge

Water is a Polar Molecule!
H2O Oxygen 3.44 Hydrogen 2.20 Drops on a Penny Snapping Drops Surface Tension Sand vs Snowman Capillary Action Melting Points Boiling Points Solubility

Carbon Dioxide is Non-Polar
CO2 Oxygen 3.44 Carbon 2.55 Δχ=0.89 O C O Why is Carbon dioxide non-polar?

Carbon Dioxide is Non-Polar
CO2 Oxygen 3.44 Carbon 2.55 Δχ=0.89 δ- δ+ δ- O C O Why is Carbon dioxide non-polar? Because it is linear or perfectly symmetrical.

O H H Water is Bent δ- δ+ δ+ Because water is not a linear molecule.
Why is Water Polar? δ+ δ+ Because water is not a linear molecule.

MOLECULAR GEOMETRY: VSEPR
δ- O H H Why is Water Polar? δ+ δ+ Because water is not a linear molecule.

H C N What about HCN? δ+ δ- CO2
Hydrogen 2.20 Carbon 2.55 Nitrogen 3.04 δ+ δ- H C N Prussic Acid Hydrogen Cyanide Prussic Acid is Polar Because it is linear but the ends have opposite charges.

Covalent Bonding Shapes VALENCE SHEELL ELECTRON PAIR REPULSION
VSEPR Covalent Bonding Shapes VALENCE SHEELL ELECTRON PAIR REPULSION

Why do these molecules look like this
Why do these molecules look like this? Can we see pictures of these molecules?

VSEPR Basics: electrons can’t stand each other!

Figuring out a Molecules Geometry
Draw Lewis structure How many things are there around the central atom? What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like? PHET SIM AND Styrofoam

Common Molecular Shapes

What Shape? Groups 2 Pairs 0 BeH2 CO2 HCN
How many things are there around the central atom? What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like? Groups 2 Pairs 0

BeH2 How many things are there around the central atom?
What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like?

CO2 Carbon Dioxide How many things are there around the central atom?

HCN Hydrogen Cynanide How many things are there around the central atom? What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like? Prussic Acid

Linear Shape BeH2 CO2 Groups 2 Pairs 0 HCN
BaF2 is an exception to VSEPR theory….non-linear….108 degeen angles…

What Shape? BCl3 BF3 CO32- COCl2 Groups 3 Pairs 0

BCl3 Boron Trichloride How many things are there around the central atom? What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like?

[CO3]-2 Carbonate Ion How many things are there around the central atom? What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like?

COCl2 Carbonyl dichloride
How many things are there around the central atom? What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like? This colorless gas gained infamy as a chemical weapon during World War Phosgene

Trigonal Planar BCl3 BF3 CO32- COCl2 Groups 3 Pairs 0

What Shape? Groups 2 Pairs 1 SO2 NO2- O3
How many things are there around the central atom? What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like? Groups 2 Pairs 1

SO2 Sulfur Dioxide Is this correct?
How many things are there around the central atom? What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like? Is this correct?

SO2 Sulfur Dioxide Not correct, there are 10 electrons in the circle.
How many things are there around the central atom? What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like? Not correct, there are 10 electrons in the circle.

SO2 Sulfur Dioxide How many things are there around the central atom?
What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like? The Single Bond is a Coordinate Covalent Bond

O3 Ozone How many things are there around the central atom?
What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like? Ozone also has a single coordinate covalent bond.

Bent Geometry SO2 NO2- O3 Groups 2 Pairs 1

Tetrahedral Shape CH4 CCl4 SO42- Groups 4 Pairs 0

CH4 Methane How many things are there around the central atom?

CCl4 Carbon TetraFluoride
How many things are there around the central atom? What structure is this molecule based on? Which atoms are replaced by lone electron pairs? What is the final structure and what are the bond angles like?

Trigonal Pyramidal NH3 NF3 PCl3 Groups 3 Pairs 1

NH3 Ammonia How many things are there around the central atom?

Bent Geometry H2O ClO2 OF2 Groups 2 Pairs 2

H20 Water How many things are there around the central atom?

Trigonal Bipyramidal PF5 PCl5 Groups 5 Pairs 0

T-Shaped PF5 PCl5ClF3 BrF3 SeO32- Groups 3 Pairs 2

Seasaw Shaped SF4 BrF4+ Groups 4 Pairs 1

Octahedral SF6 SiF63- Groups 6 Pairs 0

SF6 Sulfur hexafluoride and PF5 Phosphorous Pentafluoride

Square Pyramidal BrF5 IF5 Groups 5 Pairs1

Bicarbonate Hydrogen Carbonate Sulfate Peroxide
Ammonium Chlorite Hydroxide Thiocyanate Chromate Hydronium Chlorate Permanganate Sulfite DiChromate Nitrite Perchlorate Bicarbonate Hydrogen Carbonate Sulfate Peroxide Nitrate Acetate BiSulfate Hydrogen Sulfate Carbonate Oxalate HypoChlorite Cyanide Dihydrogen Phosphate Hydrogen Phosphate Phosphate

[ClO2]- [HSO4]- [NH4]+ [OH]- [SCN]- [CrO4]2- [H3O]+ [SO3]2- [Cr2O7]2-
[MnO4]- [SO3]2- [Cr2O7]2- [NO2]- [ClO4]- [HCO3]- [SO4]2- [02]2- [NO3]- [C2H3O2]- [HSO4]- [CO3]2- [C2O4]2- [ClO]- [CN]- [H2PO4]- [HPO4]- [PO4]3-

NH4+ H H N H H 1+ Tetrahedral 5 + 4(1) -1 = 8VEs Home
Hydrogen is never the central atom and Nitrogen is the more electronegative so it goes in the middle. H N H Tetrahedral 5 + 4(1) -1 = 8VEs H Home

H3O+ H O H H 1+ Trigonal Pyramidal Hydronium 6 + 3(1) -1 = 8VEs Home
Hydrogen is never the central atom and Oxygen is the more electronegative so it goes in the middle. H O H 6 + 3(1) -1 = 8VEs H Home

NO2- N O O 1- RESONANCE  5 + 2(6) +1 = 18VEs Bent Nitrite Home
Oxygen is more electronegative but in this case oxygen has to go on the ends. This structure must be drawn twice to show resonance. 1- N O O RESONANCE  Home

NO3- O O N O 1- RESONANCE  5 + 2(6) +1 = 18VEs
Trigonal Planar Nitrate Oxygen is more electronegative but in this case oxygen has to go on the ends. This structure must be drawn three times to show resonance. O O 1- N RESONANCE  O Home

ClO- Cl O 1- 7 + 6 +1 = 14VEs Linear Hypochlorite Home
This is a linear molecule as all two atom molecules are linear by definition. 1- Cl O Home

ClO2- Cl O O 1- RESONANCE  7 + 2(6) +1 = 20VEs Bent chlorite Home
A bent (not shown) single bond Lewis structure as shown here to the right satisfies the octet rule nicely but formal charge considerations suggest a resonance structure with a double bond and Chorine violating the octet rule. 1- Cl O O RESONANCE  Home

ClO3- Cl O O O 1- RESONANCE  7 + 3(6) +1 = 26VEs
A single bond Lewis structure as shown here to the right satisfies the octet rule nicely but formal charge considerations suggest a resonance structure with a double bond and Chorine violating the octet rule. Three structures must be drawn here. 7 + 3(6) +1 = 26VEs Trigonal Pyramidal chlorate 1- Cl O O RESONANCE  O Home

O Cl O O O ClO4- 1- RESONANCE  Tetrahedral perchlorate
A single bond Lewis structure as shown here to the right satisfies the octet rule nicely but formal charge considerations suggest a resonance structure with three double bonds and Chorine violating the octet rule. Four structures must be drawn here. 7 + 6(4) +1 = 32VEs ClO4- 1- O Cl O O RESONANCE  O Home

H O H C C O H CH3CO2- 1- RESONANCE 
Acetate is a tetrahedral carbon atom connected to a trigonal planar carbon atom. It has a double bond that requires drawing two resonance structures. Tetrahedral -- Trigonal Planar Acetate (2)4 + 3(1) +2(6) +1 = 24VEs H 1- O H C C RESONANCE  O H Home

CN- C N 1- 4 + 5 +1 = 10VEs Linear Cyanide Home
This is a linear molecule as all two atom molecules are linear by definition. In order to satistfy the octet rule a triple bond must be draw. 1- C N Home

OH- O H 1- 6 + 1 +1 = 8VEs Linear Hydoxide Home
This is a linear molecule as all two atom molecules are linear by definition. 1- O H Home

O Mn O O O MnO4- 1- RESONANCE  7 + 6(4) +1 = 32VEs Tetrahedral
A single bond Lewis structure satisfies the octet rule nicely but formal charge considerations suggest a resonance structure with three double bonds and Manganese violating the octet rule. Four structures must be drawn here and Mn has 7VEs (3d54s2) MnO4- 7 + 6(4) +1 = 32VEs 1- O Tetrahedral permanganate Mn O O RESONANCE  O Home

HCO3- H O C O O 1- RESONANCE  Bent and Trigonal Planar bicarbonate
The carbon is trigonal planar…and the Oxtgen atom is bent. Two structures must be drawn for resonance. Bent and Trigonal Planar bicarbonate (6) +1 = 24VEs 1- H O C O RESONANCE  O Home

HSO4- O H O S O O 1- RESONANCE  Bent and Trigonal Planar bisulfate
It can be drawn with all single bonds where sulfur does not violate the octet rule but in terms of formal charge the structure below is favorable. The sulfur is tetrahedral and the oxygen has a bent structure. Formal charge leads to two double bonds being drawn and the necessity of drawing resonance structures . Bent and Trigonal Planar bisulfate (6) +1 = 32VEs O 1- H O S O RESONANCE  O Home

H2PO4- O H O P O H O 1- Dihydrogen phosphate tetrahedral
It can be drawn with all single bonds where Phosphorous does not violate the octet rule but in terms of formal charge the structure below is favorable. The Phosphorous is tetrahedral and the oxygen has a bent structure. Resonance structures must be drawn. Dihydrogen phosphate tetrahedral (6) +1 = 32VEs O 1- H O P O H O RESONANCE  Home

SCN- S C N 1- Linear Thiocyanate 6 + 4 +5 +1 = 16VEs Home
This is an interesting Lewis structure as its often used to introduce formal charge. You can draw it in numerous ways. A triple Sulfur-Carbon bond and a single carbon nitrogen bond or a triple carbon-nitrogen bond and a single carbon-sulfur bond. A triple sulfur bond leads to unfavorable formal charge (-2) Alternatively, two double bonds can be drawn which results in a formal charge of -1 for nitrogen. How do we choose between the two structures with a formal charge of -1? Look at electronegativity values. Since Nitrogen is more electronegative the preferred Lewis structure is shown below; SCN- Linear Thiocyanate = 16VEs 1- S C N Home

SO32- O S O O 2- RESONANCE  Sulfite trigonal pyramidal
Formal charge leads to creating a double bond which results in needing to draw two additional resonance structures. The lone pair leads to a trigonal pyramidal structure. Sulfite trigonal pyramidal 6 + 3(6) +2 = 26VEs O 2- S RESONANCE  O O Home

SO42- O O S O O 2- RESONANCE  Tetrahedral sulfate
It can be drawn with all single bonds where sulfur does not violate the octet rule but in terms of formal charge the structure below is favorable. The sulfur is and there are 6 total resonance structures that can be drawn if we move the double bonds around.. Tetrahedral sulfate 6 + 4(6) +2 = 32VEs O 2- O S O RESONANCE  O Home

CO32- O C O O 2- RESONANCE  Trigonal Planar Carbonate
Carbonate must be drawn two additional times with resonance structures being shown. Trigonal Planar Carbonate 4 + 3(6) +2 = 24VEs O 2- C RESONANCE  O O Home

HPO42- O H O P O O 2- hydrogen phosphate tetrahedral
The location of the double bond must be moved to show resonance In total, three structures would need to be drawn. The P should be shown with a double bond to all the oxygen except for the OH group. hydrogen phosphate tetrahedral (6) +2 = 32VEs O 2- H O P O O RESONANCE  Home

CrO42- O O Cr O O 2- Chromate tetrahedral 6 + 4(6) +2 = 32VEs
Chromate has 6 electrons available for bonding so this structure looks exactly like Sulfate and need multiple resonance structures as well. Chromate tetrahedral 6 + 4(6) +2 = 32VEs O 2- O Cr O RESONANCE  O Home

Cr2O72- O O O Cr O Cr O O O 2- diChromate tetrahedral-tetrahedral
Both chromates are tetrahedral and the oxygen in the center is bent. All single bonds could be drawn but formal charges suggest two double bonds and resonance structures. diChromate tetrahedral-tetrahedral 2(6) + 7(6) +2 = 56VEs RESONANCE  O 2- O O Cr O Cr O O O Home

Oxygen bonds with itself using a singla bond.
2(6) +2 = 14VEs Linear Peroxide Oxygen bonds with itself using a singla bond. 2- O O Home

C2O42- O O C C O O 2- oxalate trigonal planar x 2
Resonance structures must be drawn to show the double bond in different locations. The two single bonded oxygens have a formal charge of -1 leading to an overall charge of 2-. oxalate trigonal planar x 2 2(4) + 4(6) +2 = 34VEs 2- O O C C O O RESONANCE  Home

PO43- O O P O O 3- phosphate tetrahedral 5 + 4(6) +3 = 32VEs RESONANCE
It can be drawn with all single bonds where Phosphorous does not violate the octet rule but in terms of formal charge the structure below is favorable. The Phosphorous is tetrahedral and the three oxygen atoms have a -1 formal charge. Resonance structures must be drawn. phosphate tetrahedral 5 + 4(6) +3 = 32VEs O 3- O P O O RESONANCE  Home

How does carbon form four bonds when there are only two electrons to pair with and one empty orbital? H C H C H H 1s2 2s2 2p6 We combine the 2s and 2p orbitals into one hybridized orbital sp3 Now there are four carbons the hydrogen can bond to. sp3

Rules for Hybridization
1) determine the number of electron clouds. 2 electron clouds = 2 hybrid orbitals sp 3 electron clouds = 3 hybrid orbitals sp2 4 electron clouds = 4 hybrid orbitals sp3 1s2 2s2 2p6 O H H We don’t have to hybridize water under the old method but we do anyways. sp3 hybridized The hydrogens now bond with the two lone electrons in oxygen. a b c d a = lone pair b = lone pair c = OH bond d = OH bond sp3 hybridized

Determine the hybridization of each central atom:
1) determine the number of electron clouds. 2 electron clouds = 2 hybrid orbitals sp 3 electron clouds = 3 hybrid orbitals sp2 4 electron clouds = 4 hybrid orbitals sp3 Determine the hybridization of each central atom:

Electrons repel one another.
Oxygen forms a double bond but the idea that there are four electrons shared right between the oxygen atoms is false. Oxygen Oxygen O O Electrons repel one another. 1s2 2s2 2p4 1) determine the number of electron clouds. 2 electron clouds = 2 hybrid orbitals sp 3 electron clouds = 3 hybrid orbitals sp2 4 electron clouds = 4 hybrid orbitals sp3 sp2 p Oxygen has sp2 hybridization and one p orbtal The other oxygen atom is the same sp2 p The two oxygen atoms bond in using a hybrid sp orbital and with a p prbital.

pi bond O O Sigma bond Go over p orbital shapes use balloons to show p bonding. The first bond is a sigma bond and acts between the inter-nuclear axis. The second bond is a pi bond and acts between overlapping p orbitals. It is weaker than a sigma bond.

Electrons repel one another.
Nitrogen forms a triple bond but the idea that there are six electrons shared right between the atoms is false. Nitrogen Nitrogen 1s2 2s2 2p4 sp p sp p Electrons repel one another. 1) determine the number of electron clouds. 2 electron clouds = 2 hybrid orbitals sp 3 electron clouds = 3 hybrid orbitals sp2 4 electron clouds = 4 hybrid orbitals sp3 Nitrogen has sp hybridization and two p orbitals The two nitrogen atoms bond in using a hybrid sp orbital and two p orbitals.

Section 1: Basic Lewis Structures

Similar presentations

Presentation on theme: "Section 1: Basic Lewis Structures"— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

Section 1: Basic Lewis Structures

Similar presentations

Presentation on theme: "Section 1: Basic Lewis Structures"— Presentation transcript:

Similar presentations

About project

Feedback