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What happens if interacting things do not want to give?. They must share…. What does it mean to share an e- ?. Linked. shared e- “belongs” to both atoms both complete octets valence energy levels of overlap the sharing/overlap binds the atoms together and is called a covalent bond. - PowerPoint PPT Presentation
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What happens if interacting things do not want to give?
They must share…
What does it mean to share an e- ?– shared e- “belongs” to both atoms– both complete octets– valence energy levels of overlap
• the sharing/overlap binds the atoms together and is called a covalent bond
Linked
Linked
Pg 309-311
Ionic vs. Covalent Bond
• Metals give e-; Nonmetals take e-; electrostatic attraction created keeps atoms together– Ions “stick” together = formula unit
• Nonmetals share e- forming overlapping valences that keep atoms together– Overlap forms a new shape=molecule
Write in the box How are these diagrams different?
Drawing Bonding
Venn diagram model
Draw Lewis symbol for Cl
Is one Cl noble gas stable?
Lewis Structure show shared pair(s) as line and unshared pairs as dots
single line = “single bond”Pg 309-311
Draw Lewis symbols for each atom of water then match up the electrons to make bonds!
Draw its Lewis structure
overlap creates a new molecule with its own shape
What about water???
Pg 309-311
Venn diagram
Try N bonding with H
• Draw Lewis structure for new molecule.
Pg 309-311
• Draw Lewis symbol for N & H
• How will they share electron pairs???
Try matching up carbon with hydrogen…
Drawing Lewis Structures “step by step” example…PCl3
1. Sum valence electrons for all atoms
2. Divide total # of ve- by 2 to give # of electron pairs
3. Determine which atom is the CENTRAL atom???
4. Surround the central atom with 4 electron pairs
5. Put the other atoms around the central atom
6. Use the remaining pairs to complete octets around each remaining atom
7. If there are not enough electron pairs to provide an octet for each atom, move nonbonding electron pairs between 2 atoms that already share a pair
Pg 317-319
PCl3 is used to make numerous phosphate compounds for industrial purposes one of which is PSCl3
which is then used to make parathion which is used as an insecticide
Lewis Structure PracticeCl2 NF3
HF CHCl3 (C is central)
Ions have a charge. How will this change your total # of valence electrons???
sulfate ion chlorate ion
Multiple Bonds
sigma (σ) bond - covalent bond in which electron density is concentrated along the internuclear axis
pi (π) bond - results from the overlap between two p orbitals oriented perpendicularly to the internuclear axis
Equivalent Resonance Structures
Draw Lewis Structure for:
SO3
Pg 322-325
Equivalent Resonance Structures
Draw Lewis Structure for:
CO3-2
Non-Equivalent Resonance Structures
What if you can draw two completely different Lewis Structures each following the octet rule, which one is most reasonable???Draw 2 different Lewis structures for:
CO2 “carbon dioxide”
Formal Charge
charge difference between valence electrons of each isolated atom and number of electrons assigned to atom in a specific Lewis Structure
The best structure has (1) the fewest formal charges and (2) the negative charge on the most electronegativity atom
Pg 320-321
VESPRValence Electron Shell-Pair Repulsion
• Electron domain – region about a central atom in which electrons are likely to be found ((bonding AND nonbonding))
• Bonding electrons – electrons shared between atoms
• Nonbonding electrons (lone pairs) – electrons that are not shared but are needed to complete atoms octet
Pg 346-357
VESPR• Electron domains (lone pairs and bonds)
will orient naturally to “try to get out of each other’s way”
• The best arrangement of a given number of electron domains is the one that minimizes the repulsion among them
• 3-d shape depends on the bond angles resulting from domain arrangement
Pg 346-357
Linked
1) draw each Lewis structure 2) determine the # of electron domains around the CENTRAL ATOM 3) how many electron domains are bonding sites?
H2O CH4
NH3
Hybrids A hybrid results from combing
two of the same types of things giving characteristics of both
• Hybridization explains bond angles and resulting geometries
• shape of a hybrid orbital is different from original
• total number of atomic orbitals remains constant
sp hybridization (example BeF2)
Be no single electrons
F 1 single electron
if Be “promotes” an electron
Then 2 single electrons are available.
BUT one s and one p would give not give the predicted symmetrical linear geometry.
sp hybridization (example BeF2)
SO valence-bond theory says they “mix” to create 2 new AND identical sp orbitals creating symmetrical geometry
Be now
has 2 identical/symmetrical
sp orbitals that can overlab
with F’s 2p orbitals
Link
sp2 hybridization
sp3 hybridization
Link
sp3d & sp3d2 hybridization
When sharing, why would one interacting thing get more than another???
Electronegativity - ability of an atom in a molecule to attract electrons to itself (electron affinity)
Pg 312-317
Linked
PolarityPg 312-317 Linked
•Polar (“puller”) – atoms pull electrons differently; results in uneven distribution
–Gives bond partial positive and partial negative “dipoles”
• Nonpolar – atoms pull electrons equally; results in even distribution
How “puller” is polar?
use electronegativity values to determine the extent of the polarity
to be “puller” difference MUST be greater than 0.4
Pg 312-317
non-puller polar bear
puller polar bearExample: Determine extent of polarity of a B – Cl bond
Dipole Moments• Which of the following bonds is the most
polar? Which one is Non-polar?
Cl – Cl H – O
C – O Br – F
N – H C – H
Molecular Polarity Dipole moment of multi-atom molecules depends on BOTH polarities of individual bonds and molecular geometry
Pg 263-266
Molecular Polarity
polar
polar
polar
non-polar
non-polar
Polarity results in ….Intermolecular Attraction
Dipole-Dipole - of one molecule attracts to the of another
Pg 445-446
Hydrogen bondingdipole-dipole attraction of H in a polar bond to an F, O, or N in another molecule
H bonding is stronger than regular dipole-dipole due to an unshared electron pairLinked
Pg 449-451
Hydrogen bonding of water
Pg 449-451
Ion – Dipole attraction
Attraction of ionic charge and partial dipole charge of a polar molecule
Pg 445-446
How do compounds dissolve???Linkedion–dipole attraction separates NaCl formula units into isolated ions
dipole-dipole attraction cause water molecules to surround and isolate sugar molecules
Naming Binary Molecular Compounds
• element furthest to the left on table should be written first
• if same group element with higher atomic # should be written first
• second element name should end with “ide”
• Greek prefixes designate # of atoms of each element
((prefix mono is NOT used for first element)))
Pg 66-67
Prefixes
1 mono 2 di 3 tri
4 tetra 5 penta 6 hexa
7 hepta 8 octa 9 nona
10 deca
SO…
CO SF6 N2O P2O3
Pg 66-67
Practice
• Cl2O3 BrF3
• I2O4 SO3
• dihydrogen monosulfide
• Iodine monobromide
• Nitrogen monoxide
• Chlorine dioxide
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