Bond Polarity and Dipole Moments

Water molecule dipole moment

Bond Polarity and Dipole Moments

The polarity of water affects its properties

– Causes water to remain liquid at higher temperature

– Permits ionic compounds to dissolve in it

In water, Oxygen pulls on the electrons more than the hydrogens do.

This makes the Oxygen end slightly negative and the Hydrogen end slightly positive.

Water molecules attract to each other with hydrogen bonds.

Describe the polar covalent bond and it’s effects between water molecules.

Covalent Bonding in Biology – 2b, 2e.2

Most molecules you learned about in Biology are covalently bonded molecules.

Covalent Bonding in Biology - cont

Knowing how many valence electrons an atom has allows you to predict how many covalent bonds it can form.

Now you can draw Lewis dot structures of molecules!

Be able to draw the Lewis diagrams of covalent molecules.

Complex Molecules

Metallic Bond – 2a.1

Metal atoms don’t hold on to electrons well in bonds.

This means that electrons are delocalized - free to roam from metal atom to metal atom

These are called metallic bonds and give metals the ability to conduct electricity (electrons)

Describe the metallic bond.

B. Ionic bonding and Structures of Ionic Compounds

Polyatomic ions work in the same way as simple ions The covalent bonds hold the polyatomic

ion together so it behaves as a unit

Ionic Compounds Containing Polyatomic Ions

• Writing Lewis Structures for Polyatomic Ions

[SO4]2- 2-

[NO2]- -

[NH4]+ +

+

Intermolecular Forces – 2d In any substance at any temperature, the

forces holding the material together are constantly working against the internal energy of particle motion. In a solid, there is not enough energy to

overcome the Intermolecular forces In a liquid, there is more energy, but only

enough to allow the liquid to take the shape of its container

In a gas, the energy has completely overcome the Intermolecular forces

As temperature (molecular motion) increases, molecules can break free of their IM forces Melting boiling

Explain how Intermolecular forces and molecular motion interact to create solids, liquids, and gases.

freezing of water.flv

Quiz Std 2.

1.) Draw the Lewis Structure for the following atoms:

K, Al, Si, O, S, N.2.) Ionic Bonds happen mainly between …..3.) Describe how Ionic Bonds form.4.)Solve the following equation;214

84Po + 242He + 20

-1e → _____239

92U + 42He → _____ + 1

0n94Be + 1

1H → _____ + 42He