Chemistry WarmUp What is a valence electron? What is a valence shell? How many electrons can be in the outermost shell for an element? Why don’t the noble gases react? *Hint* You might want to grab a textbook to help you…

The Name is Bond Chemical Bond!

Types of Bonds Intramolecular & Intermolecular There are two Major categories of Bonds Intramolecular & Intermolecular

So what is the difference between intramolecular and intermolecular bonds?

Intramolecular Bonds within one school. Intramural sports involves competition within one school. Intramolecular Bonds are attractive forces within a compound.

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

The bond between Na+1 and Cl-1 is an intramolecular Bond. Intramolecular Bonds The bond between Na+1 and Cl-1 is an intramolecular Bond.

Intramolecular Bonds Ionic – an attraction between a metal and a nonmetal or a metal and polyatomic ion. This involves a gain/loss of electrons. Covalent – an attraction between two or more nonmetals. This involves the sharing of electron pairs.

Intramolecular Bonds Polar vs. Nonpolar An unequal sharing of electrons will result in a polar molecule. All ionic compounds are polar. Covalent compounds may be polar or nonpolar.

How is Polarity determined? There are 4 simple rules to help you out!

Rules for determining Polarity 1. Check the electronegativity difference between both atoms. (If there are more than two atoms go to step #2) * The molecule is nonpolar if the difference is .4 or less. * The molecule is polar if the difference is .5 or greater.

Polarity with 3 or more atoms 2. Check the electronegativity difference between the central atom and all surrounding atoms. *If all of the differences are .4 or less then the molecule is nonpolar. *If any electronegativity difference is .5 or greater go to step 3

3. If there are any unshared pairs of electrons on the central atom, then the molecule is polar. 4. If each of the surrounding atoms are pulling with equal and opposite force then the molecule is nonpolar.

Molecule Electroneg. Difference Nonpolar Molecules A nonopolar molecule will result when 2 nonmetal atoms have an electronegativity difference below .5 Molecule Electroneg. Difference #1 H – H 2.1 – 2.1 = 0 #2 H – I 2.1 – 2.5 = .4 These molecules are considered to be nonpolar because the electron pair is equidistant from each atom.

Polar Molecules A polar molecule will result when 2 nonmetal atoms have an electronegativity difference of .5 or greater Molecule Electroneg. Difference H-Cl 2.1 – 3.0 = .9 These molecules are considered to be polar because the electron pair is held closer to the nucleus of one of the atoms.

Intermolecular Bonds An interstate highway runs BETWEEN DIFFERENT states. An INTERMOLECULAR BOND is an attraction BETWEEN DIFFERENT molecules.

Intermolecular Bonds Bond Type Bond Strength There are three different types of intermolecular bonds Bond Type Bond Strength Hydrogen 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.

CHEMISTRY WARM UP 1. What are the two types of intramolecular bonds? 2. What are the three types of intermolecular bonds? 3. What three elements can hydrogen bond to in order to be classified as a hydrogen bond?

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

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? What type of intermolecular bond exists between each molecule? H2 NH3 HCl H2O C2H6 NI3

Answers Molecule Intramolecular 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 Folks