1 / 22

Covalent Bonds: Sharing Electrons for Stability

This chapter explains the concept of covalent bonds, where atoms share electrons to achieve stability. It discusses the octet rule, ionic bonds, and the balance of attractive and repulsive forces. The effects of bonding on stability, bond length, and bond energy are also explored. Additionally, the distribution of electrons and different types of covalent bonds are discussed using Linus Pauling's electronegativity scale. The chapter concludes with a discussion on the prediction of bond types based on electronegativity differences and the properties of substances with metallic, ionic, and covalent bonds.

scutler
Download Presentation

Covalent Bonds: Sharing Electrons for Stability

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Ch 6: Covalent bonds • WHY DO ATOMS BOND?

  2. GOAL: stability • ACHIEVED: OCTET RULE • BOND: Ions/ionic bonds transfere-s/oppchgs • Covalentbonds - atoms sharevale- & remain neutral

  3. Covalent bond - atoms share e- pair/s • Balance - attractive & repulsive forces • Attraction - nuclei of 1 atom & e-sof other • Repulsion - neighboring nuclei • p191

  4. Effects of Bonding increases stability decreases potential E …lost E is transferred to surroundings 11

  5. Potential E determines Bond Length Bond length– dist. between nuclei of bonded atoms (@ lowest pot. E) ex: H-H bond length is 75 pm Remember, nuclei vibrate: bond length is averaged

  6. Bond E - force required to break a bond • higher bond E = stronger bonds = shorter bond lengths • w/bond length of 75 pm, the pot. E of H2 is 436 kJ/mol • …436 kJ to break bonds of 1 mol of H2 molecules. • ~ 104 Cal 100-calorie-snacks

  7. Bond Energy p193…Hi & Lo…

  8. molecular orbital – location of shared/bonding e-s

  9. COVALENT BONDS sharing ≠ equal

  10. Bonding typespure covalent/nonpolar covalentpolar covalent ionic • We can predict the distribution of the electrons/bond type using Linus Pauling’s electronegativity scale p194/195

  11. Bonding types

  12. NOTES • nonpolar covalent bond: 0-.5 • ex: H-H, 2.2 – 2.2 = 0 • (all diatomic molecules– molecule w/2 atoms of same element)

  13. DIATOMIC MOLECULE

  14. NOTES • polar covalent bond: .5 - 2.1 • Atom w/higher e-neg will hoard e-s →δ- • Ex: HF: 4.0 (F) - 2.2 (H) = 1.8 • H+F– • dipole – molecule w/opp partial charges δ- or δ+

  15. In general: the >r the e-neg difference, • the >r the polarity • the stronger the bond. p196

  16. Another prediction: • An ionic bond forms between a nonmetal & a metal. • A covalent bonds tend to form between 2 nonmetals. • Remember, this is a rule of thumb – actual experiments are used to determine the bond type… • Ga-F difference?

  17. Another prediction: • An ionic bond forms between a nonmetal & a metal. • A covalent bond forms between 2 nonmetals. • Remember, this is a rule of thumb – actual experiments may be used to determine the bond type… • Ga-F difference? 2.2, yet covalent

  18. Another prediction: • An ionic bond forms between a nonmetal & a metal. • A covalent bond forms between 2 nonmetals. • Remember, this is a rule of thumb – actual experiments may be used to determine the bond type… • Ga-F difference? 2.2, yet covalent • Al-Cl difference? 1.6, yet, forms crystals…is ionic

  19. The type of bond determines properties of the substance. • Ionic very strong crystal lattice structure • Covalent little attraction to neighboring molecules • Metallic (s) e-s flow freely/ = attraction to each atom

  20. Substances with Metallic, Ionic, and Covalent Bonds

  21. Classify the following cpds according to their predicted bond type: • NO 3.4 – 3.0 = .4 nonpolar covalent • CO • HF • NaCl • HBr • NaI • Ionic bond character: Na-F 3.1 ↑ % ionic character • Ca-O2.4

More Related