POLARITY AND SOLUBILITY: “Like dissolves like”. Review of shapes: What are the five basic shapes? Linear Trigonal Planar Tetrahedral Trigonal.

POLARITY AND POLARITY AND SOLUBILITY:SOLUBILITY:

““Like dissolves like”Like dissolves like”

Review of shapes:Review of shapes:What are the five basic shapes?What are the five basic shapes?

LinearLinearTrigonal PlanarTrigonal PlanarTetrahedralTetrahedralTrigonal PyramidalTrigonal PyramidalBentBent

Review of Bonding:Review of Bonding:Ionic or covalent?Ionic or covalent?

Ionic = metal + nonmetalIonic = metal + nonmetalCovalent = nonmetal + Covalent = nonmetal +

nonmetalnonmetalNonpolar Covalent = electrons Nonpolar Covalent = electrons

shared equallyshared equallyPolar Covalent = electrons Polar Covalent = electrons

shared unequallyshared unequally

Review of ElectronegativityReview of Electronegativity

Electronegativity is the ability of an atom to Electronegativity is the ability of an atom to attract electrons in a compound. attract electrons in a compound.

The The more electronegative element in a more electronegative element in a compound will pull the electrons towards compound will pull the electrons towards itself. itself.

The difference in electronegativity The difference in electronegativity determines if the bond is nonpolar, polar determines if the bond is nonpolar, polar or ionic. or ionic.

Definitions of PolarityDefinitions of Polarity Polar bond — bond involves unequal Polar bond — bond involves unequal

distribution of electronsdistribution of electrons Polar Molecule - Polar Molecule - A molecule with a net A molecule with a net

dipole as a result of the opposing charges dipole as a result of the opposing charges (i.e. having partial positive and partial (i.e. having partial positive and partial negative charges) from polar bonds negative charges) from polar bonds arranged asymmetrically arranged asymmetrically

Dipole—charges in a molecule are Dipole—charges in a molecule are separated; use andseparated; use and

Electronegativity and Bond TypeElectronegativity and Bond Type

Electronegativity difference determines the Electronegativity difference determines the type of bond formed type of bond formed

Subtract the electronegativities of the Subtract the electronegativities of the elements in the bond. elements in the bond.

If the difference is:If the difference is: 0.0 to 0.2 the bond is nonpolar covalent 0.0 to 0.2 the bond is nonpolar covalent 0.3 to 1.4 the bond is polar covalent 0.3 to 1.4 the bond is polar covalent > 1.5 the bond is ionic IF a metal is involved> 1.5 the bond is ionic IF a metal is involved

HOWEVER If only nonmetals are involved, the HOWEVER If only nonmetals are involved, the bond is considered polar covalent. bond is considered polar covalent.

Periodic Table of ElectronegativitiesPeriodic Table of Electronegativities

ExamplesExamples

Carbon DisulfideCarbon Disulfide Formula CSFormula CS22

Since the electronegativities of C and S are both 2.5, Since the electronegativities of C and S are both 2.5, the difference will be 0 and you have a nonpolar bond.the difference will be 0 and you have a nonpolar bond.

WaterWater Formula HFormula H2200

ENENHH = 2.1 = 2.1

ENENOO = 3.5 = 3.5

EN =1.4 polar covalentEN =1.4 polar covalent

More ExamplesMore Examples Sodium bromide Sodium bromide

formula = NaBr; formula = NaBr; ENENNaNa = 0.9, = 0.9,

ENENBrBr = 2.8 = 2.8

has a ΔEN = 1.9 and ionic bondhas a ΔEN = 1.9 and ionic bond

Hydrogen fluoride Hydrogen fluoride formula = HF; formula = HF; ENENHH = 2.1, = 2.1,

ENENFF = 4.0 = 4.0

ΔEN = 1.9 and polar covalent bondΔEN = 1.9 and polar covalent bond

Polarity and Molecular GeometryPolarity and Molecular Geometry

Draw Lewis Structure & Bar Draw Lewis Structure & Bar Diagram; Diagram;

Use (partial positive) and Use (partial positive) and (partial negative) to show charge (partial negative) to show charge distributiondistribution

Determine Shape of MoleculeDetermine Shape of Molecule Determine Polarity of MoleculeDetermine Polarity of Molecule

HH22OO1) Lewis & Bar?1) Lewis & Bar?

2) Shape?2) Shape?3) Polarity?3) Polarity?

O H H

O—H H

bentPolar—electrons distributed unequally

OFOF22

1) Lewis & Bar?1) Lewis & Bar?

2) Shape?2) Shape?3) Polarity?3) Polarity?

O—F

bentNonpolar—electrons distributed equally

O F F F

CFCF44

1) Lewis & Bar?1) Lewis & Bar?

2) Shape?2) Shape?3) Polarity?3) Polarity?

tetrahedral

Nonpolar—electrons distributed equally

F C F F

F F—C—F F

F

Determining solubility:Determining solubility:““Like Dissolves LikeLike Dissolves Like””

Polar compoundsPolar compounds like water like water dissolve polar and ionicdissolve polar and ionic solids solids like NaCl like NaCl

Nonpolar compoundsNonpolar compounds like oils like oils and fats and fats dissolve other dissolve other nonpolar nonpolar compoundscompounds

Determining Solubility Examples:Determining Solubility Examples:Are these pairs soluble?Are these pairs soluble?

HCl HCl HH22OO

Both are polar, therefore they Both are polar, therefore they are soluble in each other.are soluble in each other.

O—H

HH—Cl

Determining Solubility Examples:Determining Solubility Examples:Are these pairs soluble?Are these pairs soluble?

CFCF44 NHNH33

CFCF44 is nonpolar, NH is nonpolar, NH33 is polar; is polar;

therefore NOT soluble in each therefore NOT soluble in each other.other.

F—C—F F

F H—N—H H

Practical Application:Practical Application:Solubility and the Human BodySolubility and the Human BodyNonpolar compounds will be Nonpolar compounds will be

fat soluble and can be stored fat soluble and can be stored for later use. for later use.

Polar compounds will be water Polar compounds will be water soluble and are passed in the soluble and are passed in the urine if not used immediately. urine if not used immediately.

For further reading to help with your spice project. For further reading to help with your spice project. http://www.chemistry.wustl.edu/~edudev/LabTutorials/Vitamins/http://www.chemistry.wustl.edu/~edudev/LabTutorials/Vitamins/

vitamins.html vitamins.html