ROSMAWATI BINTI JAMALUDIN AMAL BINTI HARUN NORLEHA BINTI MAD DUKOL NIK ABIBAHTON BINTI NIK ALI INNOVATOR 2 INNOVATOR 3 INNOVATOR 4 INNOVATOR 1 CHEMISTRY LECTURER NEGERI SEMBILAN MATRICULATION COLLEGE QR CODE eMo.Ge LEARNING KIT
TABLE OF CONTENT STEPS TO DRAW THE LEWIS STRUCTURE THE GUIDELINES FOR PREDICTING THE MOLECULAR GEOMETRY BASED ON THE VSEPR THEORY MOLECULAR GEOMETRY WITH LONE PAIR OF ELECTRONS THE GUIDELINES FOR DETERMINING THE TYPES OF HYBRIDISATION FINGER TECHNIQUE STEP TO DETEMINE THE MOLECULAR GEOMETRY PERIOD 2 (TEMPLATE) STEPS TO WRITE THE HYBRIDISATION PROCESS (TEMPLATE) DRAW THE ORBITAL OVERLAPPING (TEMPLATE) THE GUIDELINES FOR DEDUCING THE POLARITY OF A MOLECULE STEPS IN DETERMINE THE TYPES OF INTERMOLECULAR FORCES EXERCISES ANSWERS A simple innovation tool made of laminated paper. It’s contains: • brief notes on the topic Chemical Bonding and template for hybridisation process. • a replica model TOH to represent the 5 types of overlapping orbital sp, sp2 , sp3 , sp3d and sp3d2 1 2 4 8 9 11 16 18 19 20 STEP TO DETEMINE THE MOLECULAR GEOMETRY PERIOD 3 & ABOVE (TEMPLATE) STEPS TO WRITE THE HYBRIDISATION PROCESS (TEMPLATE) DRAW THE ORBITAL OVERLAPPING (TEMPLATE) 14
Determine the central atom (the least electronegative atom). Sum the no. of valence electrons of all atoms in the molecule or ion. For ion: • One electron is added for each unit of negative charge • One electron is subtracted for each unit of positive charge Draw a skeletal structure by connecting the central and terminal atoms together. Distribute the remaining electrons to the terminal atoms, so that each atom achieves octet configuration (except H- duplet) For any remaining valence electrons, place the electrons on the central atom as a lone pair electrons. 1 2 4 5 3 STEPS TO DRAW THE LEWIS STRUCTURE 1
Draw the plausible Lewis structure Count the total number of electron pairs (bonding pairs + lone pairs electrons) at the central atom Apply the VSEPR theory to determine the molecular geometry / shape. Establish the electron pair geometry of the central atom THE GUIDELINES FOR PREDICTING THE MOLECULAR GEOMETRY BASED ON THE VSEPR THEORY 2
The electron pairs in a valence shell surrounding a central atom repel each other. As a result, both bonding pairs and lone pairs of electrons arrange themselves to be as far apart as possible, to minimise the repulsion. A lone pair of electrons repels other electron pairs more strongly than a bonding pair, does the repulsion between electron pairs decreases in the following order: L.P – L.P > L.P – B.P B.P – B.P > A A A L.P denotes lone pair B.P denotes bonding pair Valence Shell Electron Pair Repulsion (VSEPR) theory. 3
Class No. of bonding pairs electrons at central atom No. of lone pairs electrons at central atom Electron Pair Geometry Molecular Geometry AX3 3 0 Trigonal planar Molecular Geometry 2 1 Bent @ V-shaped AX2E Trigonal planar Trigonal planar <120O AX2 2 0 Linear Linear X A X 1800 A X X 1200 X A X X MOLECULAR GEOMETRY WITH LONE PAIR OF ELECTRONS 4
AX2E2 2 2 Bent @ V-shaped Tetrahedral Class Electron Pair Geometry Molecular Geometry AX4 4 0 Tetrahedral A X X X Molecular Geometry 3 1 Trigonal pyramidal AX3E Tetrahedral Tetrahedral X A X A X X X X 109.5O <109.5O <109.5O No. of bonding pairs electrons at central atom No. of lone pairs electrons at central atom 5
AX4E 4 1 Trigonal bipyramidal Seesaw @ distorted tetrahedron AX3E2 2 3 Linear Class Electron Pair Geometry Molecular Geometry AX5 5 0 Trigonal bipyramidal Trigonal bipyramidal Molecular Geometry AX2E3 3 2 Trigonal bipyramidal Trigonal bipyramidal T-shaped X A X X A X X A X X X A X X X X X X <90O <90O <120O 180O 90O 120O No. of bonding pairs electrons at central atom No. of lone pairs electrons at central atom 6
A X AX5E 5 1 Octahedral Square pyramidal AX4E2 4 2 Square planar Octahedral Class Electron Pair Geometry Molecular Geometry AX6 6 0 Octahedral Octahedral A X X X X X X Molecular Geometry X X X 90O <90O A X X X X X 90O No. of bonding pairs electrons at central atom No. of lone pairs electrons at central atom 7
Draw a plausible Lewis structure Count the total number of electron pairs (bonding pairs + lone pairs) around a central atom (A double / triple bond is considered as one bonding pair) Type of hybridisation The total no. of electron pairs Type of hybridisation Total no. of electron pairs 2 sp 3 sp2 4 sp3 5 sp3d 6 sp3d2 No. of hybrid orbitals 2 3 4 5 6 = = = = = = THE GUIDELINES FOR DETERMINING THE TYPES OF HYBRIDISATION The no. of Hybrid orbitals = 8
s p p p d d 6 Left hand Right hand Type of hybridisation Total no. of electron pairs No. of hybrid = orbitals Lewis structure FINGER TECHNIQUE 9
1 2 3 4 5 6 1 2 1 2 3 1 2 3 4 1 2 3 4 5 1 2 3 4 5 6 STEPS TO DETERMINE THE HYBRIDISATION OF ATOMIC ORBITALS 10
Electron-pair geometry : Molecular geometry Calculate no. of valence electron Draw the Lewis Structure Total valence electron total Bonding ee- remain State bond angle: No. of bonding pairs No. of lone pairs Total electron pairs STEP TO DETEMINE THE MOLECULAR GEOMETRY 1 6 5 4 3 2 (name & draw the molecular geometry): 11
Atom Total electron pair No. of hybrid orbital Type of hybridisation Lewis structure: Hybridisation Process: _ (ground state): 2s 2p _ (excited state): _ (hybridised state): 2s 2p _ bond + _ bond = need _unpaired electron STEPS TO WRITE THE HYBRIDISATION PROCESS (PERIOD 2) Prepare hybridization process & draw valence orbital diagram of central atom Label type of hybridisation 12
DRAW THE ORBITAL OVERLAPPING Using TOH kit , draw the orbital overlapping (orbital overlapping based on the molecular geometry) 13
___ (ground state): _s _p _d ___ (excited state): _s _p _d ___ (hybridised state): _ bond + _ bond need _ unpaired electron Atom Total electron pair No. of hybrid orbital Type of hybridisation Lewis structure: Hybridisation Process: Label type of hybridisation STEPS TO WRITE THE HYBRIDISATION PROCESS (PERIOD 3 & ABOVE) Prepare hybridisation process & draw valence orbital diagram of central atom 14
DRAW THE ORBITAL OVERLAPPING Using TOH kit , draw the orbital overlapping (orbital overlapping based on the molecular geometry) 15
Draw the molecular geometry Identify polar bonds in the molecule. Indicate each bond dipole using a vector quantity (from the less electropositive to the more electropositive atom) Determine the sum of vectors of bond dipoles in the molecule. If = 0 non-polar molecule. If ≠ 0 polar molecule. THE GUIDELINES FOR DEDUCING THE POLARITY OF A MOLECULE 16
Type of covalent bond Polar bond Non-polar bond Molecular Geometry Symmetrical shape (Linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral, square planar) Unsymmerical @ asymmetrical shape (Bent, trigonal pyramidal, seesaw, T-shaped, square pyramidal) Different terminal atom Same terminal atom Bond dipoles cannot cancel each other ; µ ≠ 0 Bond dipoles cancel each other ; µ = 0 POLAR MOLECULE NON-POLAR MOLECULE No dipole moment µ = 0 STEPS TO DETERMINE THE POLARITY OF MOLECULE 17
Is the molecule POLAR London forces only (between temporary and induced dipoles) Example : He, P4 , Cl2 , H2 No Yes Dipole-dipole interactions (between permanent dipoles) Example : HCl, CH3Cl, H2S Hydrogen bond Example : NH3 , H2O, HF Is there any H atom bonded to N, O or F atom? Yes No van der Waals forces STEPS IN DETERMINE THE TYPES OF INTERMOLECULAR FORCES 18
EXERCISES 1. CH3F 2. AsCl5 3. XeF4 4. ICl3 5. BrF5 6. SeF4 7. PH4 + 8. ICl2 – 9. HCN 10. OCN – Predict molecular geometry, describe the hybridisation of the central atom using orbital diagrams and draw the overlapping of orbitals for the formation of bonds in each of the following molecules. 19
ANSWERS CH3F QUESTION 1 AsCl5 QUESTION 2 XeF4 QUESTION 3 ICl3 QUESTION 4 BrF5 QUESTION 5 PH4 + QUESTION 7 SeF4 QUESTION 6 ICl2 – QUESTION 8 HCN QUESTION 9 OCN – QUESTION 10 20
NOTES