Ch05 - Chapter 4 Covalent Bond: molecular compounds + 0.74...

Info iconThis preview shows pages 1–17. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 4 Chapter 4
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
E 0 - + kJ/mol Covalent Bond: molecular compounds r 0.74 Å Bond length bond energy -436 H H H 2 + + © Kay Sandberg Section 5.1
Background image of page 2
Lewis symbol: Dots represent valence electrons H H H H Covalent bond + + + + A pair of electrons i.e., 2 electrons © Kay Sandberg Section 5.1
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
+ + H H Because the 2 H’s have the same electronegativity ( χ = 2.2), the electrons are shared equally. ∆χ = 0.0 0 1 2 3 4 5 Atomic # Li B N O F C Na K Rb Cl Br I Al H Electronegativity ( χ ) © Kay Sandberg Section 5.2
Background image of page 4
E H ©Lori Petrovich H No electronegativity Difference. Each H is equally attractive to the e- Equal sharing – non-polar bond Section 5.2
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Make ionic bond, i.e., electron transfer EN difference is large. χ = 1.0 χ = 4.0 ∆χ = 3.0 NM more EN: “takes” electron F Li + - Li F M NM 0 1 2 3 4 Atomic # Li B N O F C Na K Rb Cl Br I Al H Electronegativity ( χ ) © Kay Sandberg ection 5.2
Background image of page 6
E Li 1+ F 1- Huge electronegativity Difference. F is much more attractive to the e- Decisive Victory – ionic compound Section 5.2 ©Lori Petrovich
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
+ Li + + + Li + Li + Li + Li - F - F - F Covalent bond: nuclei attracted to electron density between them: •directional Ionic bond: electrostatic attraction between charged spheres Cations attracted to anions in 3-dimensions: •nondirectional Ionic cmpds vs molecular cmpds © Kay Sandberg Section 5.2
Background image of page 8
∆χ > 1.8: bond is considered ionic. ∆χ < 0.4: bond is considered covalent. 0.4 ∆χ 1.8: bond is considered ?????. covalent bond ionic bond + - Li F + + H H ∆χ = 3.0 ∆χ = 0.0 © Kay Sandberg ection 5.2
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
H Cl χ = 2.1 χ = 3.0 ∆χ = 0.9 Cl is not electronegative enough to “take” H’s valence electron but Cl is electronegative enough to “hog” H’s valence electron. δ + δ - Partial + Partial - 2 poles Polar covalent bond Bond dipole H Cl Cl H © Kay Sandberg ection 5.2 “+” goes on less EN atom
Background image of page 10
E H δ + Cl δ - Some electronegativity Difference. e- is more attracted to Cl, but still visits H Unfair matchup – polar covalent bond Section 5.2 ©Lori Petrovich δ + means something between 0 and 1+ 0.4 ∆χ 1.8: bond is considered polar covalent
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Tendency of an atom to draw electrons in a covalent bond toward itself. Electronegativity Electronegativity (EN): To determine the polarity of a bond To determine the polarity of a bond: examine the ∆χ of the atoms bonded. The bigger ∆χ , the more polar the bond. 0 1 2 3 4 5 Atomic # Li B N O F C Na K Rb Cl Br I H Be Electronegativity ( χ ) © Kay Sandberg Section 5.2
Background image of page 12