Exceptions to the Octet Rule Hybridization Objective Today

Exceptions to the Octet Rule Hybridization

Objective Today I will be able to: Determine the exceptions to the octet rule Predict the molecular shape of a molecule using the VSEPR theory Apply hybridization to determining the orbital shape of a molecule Evaluation/ Assessment Informal assessment – Listening to group interactions as they complete the exeptions to the octet Lewis Structure Practice Formal Assessment – Analyzing student responses to the exit ticket and the Lewis Structure Practice. Common Core Connection Make sense of problem and persevere in solving them Reason abstractly and quantitatively Use appropriate tools strategically Look for and make use of structure

Lesson Sequence • • Warm – Up Evaluate: Bonding and Nomenclature Exam Part 1 – Formal Assessment • • Explain: Molecular Polarity Elaborate: Molecular Shapes Lab Polarity – Formal and informal assessment • • Engage: Holiday Activity Evaluate: Exit Ticket • Formal assessment

Warm - Up • What molecular shapes allow for a molecule to have an expanded octet? • Draw the Lewis Structure for BF 3 – What is its molecular shape? – What angles are present in the shape? – Polar or nonpolar?

Objective • Today I will be able to: – Predict the molecular shape of a molecule using the VSEPR theory – Apply hybridization to determining the orbital shape

Homework • STEM Fair Presentations – January 23 • Finish VSEPR Theory Practice

Agenda • • • Warm – Up Pass out course recommendation slips Exceptions to the Octet Rule notes VSEPR Theory Practice Hybridization Exit Ticket

Exceptions to the Octet Rule Notes

Exceptions to the Octet Rule • Molecules with an odd number of valence electrons – Example: NO

Exceptions to the Octet Rule • Free Radical – unpaired electrons • Occurs in molecules with an odd number of electrons • Typical causes of free radicals - increased oxygen (take in ozone) - smoking - UV light

Exceptions to the Octet Rule • Free Radicals (continued) • Can damage cells, and cause advanced aging • Antioxidants bind with free radicals, making them significantly less harmful

Exceptions to the Octet Rule • Less than an Octet

Exceptions to the Octet Rule • BF 3 commonly bonds with NH 3

Exceptions to the Octet Rule • More than 8 valence electrons • Occur in atoms that have the 3 d sublevel available for bonding

Exceptions to the Octet Rule • Atoms that only have two valence electrons • H, He, Li, and Be • Stable with only two valence electrons in their s sublevel

VSEPR Theory Practice Work with the people in your row. We will review the answers as a class

Draw the Lewis Structures for the following molecules • • • Determine the shape CH 3 Cl CH 2 O BCl 3 PF 5 • • SF 6 Xe. F 4 SF 4 ICl 3

Hybridization

Hybridization

What is hybridization? • Atoms use their valence electrons to form bonds. But how is it that they form bonds of equal energy when some of the electrons come from the s orbital and some come from the p orbital? ? • Hybrid orbitals are orbitals of equal energy (between the energy of s & p orbitals) produced by the combination of two or more orbitals on the same atom.

Hybridization • An atom in a molecule may adopt a different set of atomic orbitals (called hybrid orbitals) than those it has in the free state. • See B&L pages 319 -322 for explanation and diagrams of electron promotion

• The hybridization of a particular molecule is determined by the central atom. • We only need to worry about it’s valence electrons.

Your Hybridization Options: • • • sp sp 2 sp 3 d 2 sp 3 d 3

Hybridization Be. F 2 Look at B Write the orbital diagram for B You need to have 2 e- available to bond to F Write a new orbital diagram Promote electrons

Be. F 2 http: //wps. prenhall. com/wps/media/objects/3081/3155729/blb 0905/bl 09 p 312 b. jpg

Hybridization BCl 3 Look at B Write the orbital diagram for B Promote electrons

Exit Ticket • Determine the shape of the following molecules – Xe. F 4 – PCl 5 – NH 3

http: //www. dlt. ncssm. edu/tiger/diagrams/moleculargeometry/BCl 3_Hybrid. gif

Consider CH 4 Carbon has 4 valence electrons 1 s 2 2 p 2 2 of the electrons are in the s orbital and 2 are in the p orbital. s & p have different shapes and different amounts of energy.

Consider CH 4 To create 4 equal bonds, carbon’s one 2 s and three 2 p orbitals fuse into 4 new identical orbitals called sp 3. 2 p 2 s Hybridization sp 3

• What type of hybridization does BF 3 have? • 1 s 2 2 p 1 Empty hybridized orbitals are dropped 2 p Hybridization sp 3 2 s sp 2 So sp 3 becomes sp 2

How do you include lone pairs of ein hybridization? • Each lone pair of electrons has it’s own hybridized orbital. • See next slide.

What type of hybridization does H 2 O have? Oxygen e- configuration 1 s 2 2 p 4 (Use oxygen because it is the central atom) 2 p 2 s Hybridization sp 3

• Draw the hybridization orbital diagram for phosphorus in PCl 3

Try this hybridization animation http: //www. mhhe. com/physsci/chemistry/esse ntialchemistry/flash/hybrv 18. swf