The Name is BondThe Name is Bond

Chemical Bond!Chemical Bond!

Types of BondsTypes of Bonds

There are two Major categories of BondsThere are two Major categories of Bonds

IntraIntramolecularmolecular

& & InterIntermolecularmolecular

So what is the difference between So what is the difference between intramolecular intramolecular and and intermolecularintermolecular

bonds?bonds?

Intramolecular BondsIntramolecular Bonds

IntramuralIntramural sports involves competition sports involves competition

withinwithin one school.one school.

IntramolecularIntramolecular Bonds are attractive forces Bonds are attractive forces withinwithin a compound.a compound.

Intramolecular BondsIntramolecular Bonds

The bond between The bond between Oxygen and Oxygen and Hydrogen in a water Hydrogen in a water molecule is an molecule is an intramolecular bond. intramolecular bond.

Intramolecular BondsIntramolecular Bonds

The bond between NaThe bond between Na+1 +1 and Cland Cl-1-1 is an is an intramolecular Bond.intramolecular Bond.

Intramolecular BondsIntramolecular Bonds

IonicIonic – – an attraction between a metal and an attraction between a metal and a nonmetal or a metal and polyatomic ion. a nonmetal or a metal and polyatomic ion.

This involves a gain/loss of electrons.This involves a gain/loss of electrons.

CovalentCovalent – an attraction between two or – an attraction between two or more nonmetals. This involves the sharing more nonmetals. This involves the sharing

of electron pairs.of electron pairs.

Intramolecular Bonds

Polar vs. NonpolarPolar vs. Nonpolar An unequal sharing An unequal sharing

of electrons will of electrons will result in a polar result in a polar molecule. molecule.

All All ionicionic compounds compounds are are polarpolar. .

CovalentCovalent compounds may be compounds may be polarpolar or or nonpolarnonpolar..

How is Polarity determined?How is Polarity determined?

There are 4 simple rules to help There are 4 simple rules to help you out!you out!

Rules for determining PolarityRules for determining Polarity1. Check the electronegativity 1. Check the electronegativity

difference between both atoms.difference between both atoms.((If there are more than two atoms go If there are more than two atoms go to step #2to step #2)

* The molecule is nonpolarmolecule is nonpolar if the difference is .4 or lessdifference is .4 or less..

* The * The molecule is polarmolecule is polar if the if the difference is .5 or greaterdifference is .5 or greater..

Polarity with 3 or more atomsPolarity with 3 or more atoms

2. Check the electronegativity difference 2. Check the electronegativity difference between the central atom and all between the central atom and all surrounding atoms.surrounding atoms.

*If all of the differences are .4 or less *If all of the differences are .4 or less then then the the molecule is nonpolar.molecule is nonpolar.

*If any electronegativity difference is .5 *If any electronegativity difference is .5 or greater go to step 3or greater go to step 3

3. If there are any unshared 3. If there are any unshared pairs of electrons on the pairs of electrons on the central atom, then the central atom, then the molecule is molecule is polarpolar..

4. If each of the surrounding 4. If each of the surrounding atoms are pulling with equal atoms are pulling with equal and opposite force then the and opposite force then the molecule is molecule is nonpolarnonpolar..

Nonpolar MoleculesNonpolar Molecules A nonopolar molecule will result when 2 A nonopolar molecule will result when 2 nonmetal atoms have an electronegativity nonmetal atoms have an electronegativity

difference below .5difference below .5

MoleculeMolecule Electroneg.Electroneg. DifferenceDifference #1 H – H#1 H – H 2.1 – 2.1 = 2.1 – 2.1 = 0 0

#2 H – I #2 H – I 2.1 – 2.5 = .4 2.1 – 2.5 = .4

These molecules are considered to be nonpolar These molecules are considered to be nonpolar because the electron pair is equidistant from because the electron pair is equidistant from

each atom.each atom.

Polar MoleculesPolar MoleculesA polar molecule will result when 2 A polar molecule will result when 2

nonmetal atoms have an nonmetal atoms have an electronegativity difference of .5 or electronegativity difference of .5 or

greatergreater

MoleculeMolecule Electroneg.Electroneg. DifferenceDifference H-ClH-Cl 2.1 – 3.0 = .92.1 – 3.0 = .9

These molecules are considered to be These molecules are considered to be polar because the electron pair is held polar because the electron pair is held

closer to the nucleus of one of the closer to the nucleus of one of the atoms.atoms.

Intermolecular BondsIntermolecular Bonds

An interstate highway runs An interstate highway runs BETWEEN BETWEEN DIFFERENTDIFFERENT states.states.

An An INTERMOLECULAR BONDINTERMOLECULAR BOND is an is an attraction attraction BETWEEN DIFFERENTBETWEEN DIFFERENT molecules.molecules.

Intermolecular BondsThere are three different types

of intermolecular bonds

Bond Type Bond StrengthHydrogen Strong

Dipole-Dipole Medium

London Forces Weak

(Dispersion)

Intermolecular Bonds

Hydrogen Bonds (aka H bonds) These bonds may occur between

covalent polar molecules.

H-bonds occur when Hydrogen of one molecule is bonded DIRECTLY to an atom of F, O, or N atom from an adjacent molecule.

Intermolecular Bonds

Dipole – Dipole Bonds Dipole – Dipole Bonds May occur between May occur between polar polar covalent molecules.covalent molecules.There is an attraction between the positive end There is an attraction between the positive end of one molecule and the negative end of of one molecule and the negative end of another molecule.another molecule.

Intermolecular Bonds

London Forces

(akaDispersion Forces)

These bonds occur between nonpolar molecules.

They are represented by the black dashes between the molecules

So What Do YOU Know?So What Do YOU Know?

What type of intermolecular bond exists What type of intermolecular bond exists between each molecule?between each molecule?

H2

NH3

HCl

H2O

C2H6

NI3

AnswersAnswers

MoleculeMolecule Intramolecular BondIntramolecular Bond

H2 London

NH3 Hydrogen

HCl Dipole - Dipole

H2O Hydrogen

C2H6 London

NI3 Dipole - Dipole

Intermolecular Bonds

Rank the compounds from lowest boiling point to highest boiling point.

CH4

HF

NBr3

Intermolecular Bonds

Rank the compounds from lowest boiling point to highest boiling point.

CH4 1

HF 3

NBr3 2

That’s all FolksThat’s all Folks