1

+-

+ -

+-BONDIN

G

2

3

+-

+ -

+-IO

NIC

BONDIN

G

4

IONIC RADII

+-

Zeff

5

MONOATOMIC CATIONS

LOW IONIZATION ENERGY ELEMENTSELECTROPOSTIVE ELEMENTS LOSE SOME OR ALL OF THEIR VALENCE ELECTRONS

LOSE HIGHEST n QUANTUM NUMBER FIRSTTRANSITION ELEMENTS: HIGHEST ns FIRST; THEN d

Na: [Ne]3s1 Na1+: [Ne]Ca: [Ar]4s2 Ca2+: [Ar]

Fe: [Ar]3d64s2 Fe2+ : [Ar]3d6

Fe3+ : [Ar]3d5

LOSE HIGHEST SUBLEVEL (l) FIRST

Sn: [Kr]4d105s25p2 Sn2+: [Kr]4d105s2

Sn4+: [Kr]4d10

REMINDER: CATION RADIUS < ATOM RADIUS

6

MONOATOMIC ANIONS

ELECTRONEGATIVE ELEMENTS GAIN ELECTRONS

NUMBER GAINED IS AMOUNT NEEDED TO FILL VALENCE ORBITALS ....HIGHEST p SUBLEVEL

O: [He]2s22p4 O2-: [He]2s22p6 O2-: [Ne]

I: [Kr]4d105s25p5 I1- : [Kr]4d105s25p6 I1- : [Xe]

REMINDER: ANION RADIUS > ATOM RADIUS

TO HELP REMEMBER MONOATOMIC ANION CHARGE:

GROUP NUMBER - EIGHT …….OR

EIGHTEEN - GROUP NUMBER

7

IONIC COMPOUNDS

ELECTROPOSITIVE ELEMENT TRANSFERS OR LOSES ELECTRON(S) TO THE ELECTRONEGATIVE ELEMENT

METAL LOSES ELECTRON(S) TO NON-METAL

NaF CaF2 FeF3

8

9

COVALENT BONDS

10

IONIC BONDS:

TRANSFER ELECTRONS FROM HIGHER E ORBITALS TO LOWER E ORBITALS

USUALLY: METAL + NON-METAL

NOT INDIVIDUAL MOLECULES

SPHERICAL, NON-DIRECTIONAL CHARGE

NaCl MgF2 BaO

COVALENTBONDS

SHARING OF ELECTRONS

USUALLY: BETWEEN NON-METALS

DIRECTIONAL BONDS

INDIVIDUAL MOLECULES

CO CO2 C2H5OH

11

POLAR COVALENT BONDS

ELECTRONEGATIVITY (): MEASURE OF ATOM’S ABILITY TOATTRACT BONDING ELECTRONS

NON-POLAR COVALENT BOND: = 0 H2, Cl2, O2

POLAR COVALENT BOND: > 0 HCl, H2O, ICl

H Cl

= 2.1 3.0 = 0.9

BOND DIPOLE

BOND POLARITY INCREASESAS INCREASES

ROUGH RULE: > 1.8, BOND IS CLASSIFIED AS IONIC

METAL + NON-METAL = IONICNON-METAL + NON-METAL = COVALENT

. ...

12

IN EACH OF THE FOLLOWING, IDENTIFY THE MORE POLARBOND AND INDICATE THE DIRECTION OF THE DIPOLE.

P-F OR S-F

N-F OR P-F

C-H OR O-H

Al-Cl OR Si-Cl

REMEMBER: INCREASES UP A GROUPAND ACROSS THE PERIOD

S > P

P-F > S-F

P-F IS MORE POLARDIPOLE TOWARDS F

N > P P-F IS MORE POLARDIPOLE TOWARDS F

O > C O-H MORE POLARDIPOLE TOWARDS O

Si > Al Al-Cl MORE POLARDIPOLE TOWARDS Cl

IONIC

13

LEWISSYMBOLS:

PICTORIAL REPRESENTATIONS OF VALENCE SHELL ELECTRONS

SHOWS OUTERMOST ELECTRONS IN4 “ORBITALS” FOLLOWING HUND’S RULE

C

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

OCTET

DUET

14

FF F FF FFF

BONDING PAIRNONBONDING PAIRS(LONE PAIRS)

TO DETERMINE LEWIS STRUCTURES, YOU NEED:

ELECTRONS REQUIRED:ER = 8 x NON-H ATOMS + 2 x H ATOMS

VALENCE ELECTRONS AVAILABLEVE = (VALENCE ELECTRONS IN ALL ATOMS)

SHARED PAIRS (NUMBER OF BONDS) SP = ½ (ER-VE)

LONE PAIRS = ½ (VE) - SP

15

GUIDES FOR DETERMINING LEWIS STRUCTURES OF SYSTEMS OBEYING THE OCTET (DUET) RULE

DETERMINE ER, VE, SP, & LP

DRAW MOLECULE WITH SINGLE BONDS

UNLESS NOTED: FIRST ATOM IS CENTRAL

ADD OTHER BONDS TO SATISFY SP

ADD LONE PAIRS TO SATISFY OCTET(S)

ON MOST ELECTRONEGATIVE ATOMS FIRST

WORTH NOTING:

H ATOMS CAN ONLY HAVE 1 BOND (TERMINAL ATOMS)

HALOGENS: 1 BOND UNLESS CENTRAL ATOM

16

DRAW LEWIS STRUCTURES FOR:

CH4

H2O

ER =

VE =

SP =

ER =

VE =

SP =

LP =

LP =

17

DRAW LEWIS STRUCTURES FOR:

F2

HCl

ER =

VE =

SP =

ER =

VE =

SP =

LP =

LP =

18

DRAW LEWIS STRUCTURES FOR:

PF3

NH3

ER =

VE =

SP =

F P F

F

ER =

VE =

SP =

LP =

LP =

19

WHAT IS THE LEWIS STRUCTURE OF O2?

ER = 8 x # O ATOMS16 ELECTRONS NEEDED

VE = 2 O ATOMS x 6 e- PER ATOM12 ELECTRONS AVAILABLE

SP = ½(ER-VE) = ½ (16-12)

2 SHARED PAIRS 2 BONDS

O O

WHAT IS THE LEWIS STRUCTURE OF C2H2?

ER = 2 x 8 e- + 2 x 2 e- 20 e-

VE = 2 C ATOMS x 4 e- + 2 H ATOMS x 1 e-10e-

SP = 1/2 (20 e- - 10e-)

5 SHARED PAIRSH C C H

LONE PAIRS = ½ (VE) - SP = ½ (12) - 2 =4

20

BOND ORDER: NUMBER OF SHARED ELECTRON PAIRSC C

C C

C C

BO = 1 OR SINGLE BONDBO = 2 OR DOUBLE BOND

BO = 3 OR TRIPLE BOND

BOND STRENGTH OF A SPECIFIC BOND INCREASES AND BOND LENGTH DECREASES AS BOND ORDER INCREASES

CO C O C O

CO C O C O

STRENGTH

LENGTH

< <

> >

358 799 1058 kJ/MOLE

1.43 1.23 1.13 Ao

21

MOLECULARSTRUCTURE

VSEPR

22

VALENCE SHELL ELECTRON PAIR REPULSION

VS E P RELECTRON REGIONS OR GROUPS OF NEGATIVE CHARGE

AROUND AN ATOM REPEL ON ANOTHERATTAIN POSITION TO MINIMIZE REPULSION

1 ELECTRON GROUP OR ELECTRON REGION IS A:

LONE PAIR

SINGLE BOND

DOUBLE BOND

TRIPLE BOND

THE MOLECULAR SHAPE IS DETERMINED USING THESE ELECTRON GROUPS

23

What does it mean to hybridize?

• Hybridization is the “chemistry word” for promoting electrons to an empty orbital

3 6 2 6

2 4 5 3

1 7 1 7

5 8 4 8

The #2 “s” electron becomes a “p” and #5 “p” becomes a “s”!

Hybridization Summary Table

Geometry HybridizationTotal e-

pairsShared pairs

Lone pairs

Angle Sketch

Linear sp 2 2 0

Trigonal Planar

sp2 3 3 0

Bent sp2 3 2 1

Linear sp2 3 1 2

Tetrahedral sp3 4 4 0

Trigonal Pyramidal

sp3

4 3 1

Bent Angularsp3

4 2 2

Linearsp3

4 1 3

Hybridization Summary Table

Geometry HybridizationTotal e-

pairsShared pairs

Lone pairs

Angles Sketch

Trigonal bipyramidal

sp3d 5 5 0

See-Saw sp3d 5 4 1

T-shaped sp3d 5 3 2

Linear sp3d 5 2 3

Linear sp3d 5 1 4

Hybridization Summary Table

Geometry HybridizationTotal e-

pairsShared pairs

Lone pairs

Angles Sketch

ocatahedralsp3d2

6 6 0

Square pyramidal

sp3d2

6 5 1

Square planar

sp3d2

6 4 2

T-shapedsp3d2

6 3 3

Linearsp3d2

6 2 4

Linearsp3d2

6 1 5

27

OBEY OCTET RULE: 2, 3, OR 4 ELECTRON GROUPS

180 o

120 o

109 o

THE “MOLECULAR SHAPE” ANALYSIS INCLUDES:

DETERMINE NUMBER OF ELECTRON GROUPS

DETERMINE APPLICABLE SHAPE

NAME THE SHAPE

LINEARTRIGONAL

PLANER TETRAHEDRAL

28

WHAT IS THE SHAPE OF THE FOLLOWING:

PF3

CH4

O3

F P F

F

TRIGONAL PYRAMIDAL~109 o BOND ANGLE

P

FF F

H

H C H

H

TETRAHEDRAL109 o BOND ANGLEC

HH

H

H

O O OBENT

~120 o BOND ANGLE

O

O O

29

MORE THAN 4 ELECTRON REGIONS?

5 = TRIGONAL BIPYRAMIDAL

6 = OCTAHEDRAL

30

LARGE MOLECULES? DIFFERENT REGIONS!

CAEFFINE

LINEAR

TETRAHEDRAL

TRIGONAL PLANAR

31

BOND ORDER (AGAIN)!

FF

ELECTRON DENSITY

INTERNUCLEAR AXIS BONDNODAL PLANE

BOND

EVERY BOND CONTAINS 1 BONDMULTIPLE BONDS CONTAIN 1 BOND + BONDS

FF SINGLE BOND = BOND

O ODOUBLE BOND = BOND + 1 BOND

H C C H TRIPLE BOND = BOND + 2 BONDS

32

HYBRIDIZATION RULESONLY FORM IN MOLECULES; NOT ATOMS

COVALENTLY BONDED POLYATOMIC MOLECULESONLY MIX NON-DEGENERATE ORBITALSsp, spd BUT NOT ss OR ppREQUIRES ENERGY INPUT

O

O H

H C O

H C O H

H O C H

H C O C

H

sp3

4 BONDS

sp2

1 C-C1 C-H1 C-OOTHER pORBITAL ISIN BOND

3

C-O

33

VALENCE BOND THEORY LOCALIZES BONDING ELECTRONSDIFFICULT TO EXPLAIN RESONANCE

MOLECULAR ORBITAL THEORY DELOCALIZES ELECTRONS

C C

FREEDOM TO MOVEFREEDOM TO SPREAD

34

35

+-

+ -

+-METALLI

C BONDIN

G

Metallic Bonding• With atoms of the same metallic element

• Delocalized electron clouds caused by metallic atoms being so physically close to each other

• Known as a “sea of electrons”

• Reason why metals are such good conductors

36