Bell work Draw a solid Work on the first column of terms for chapter 10

Bell work What is an ionic bond?

Johannes Diderik van der Waals The theory that describes the electrostatic attraction between molecules is called van der waals forces

Van der Waals His work also on the kinetic theory of gases led to further work on the continuity of the liquid and gaseous states He received the noble prize for physics in 1910

We can see his work take place around us in God’s creation today : The van der Waals forces is the force to which the gecko's climbing ability is attributed. A gecko can hang on a glass surface using only one toe. Efforts continue to create a synthetic "gecko tape" that exploits this knowledge.

More on the gecko So far, research has produced some promising results - early research yielded an adhesive tape product, which only obtains a fraction of the forces measured from the natural material, and new research has yielded a discovery that purports 200 times the adhesive forces of the natural material.

Intermolecular forces Forces that play an important role in determining the physical properties of various substances Classified into three groups –Dipole – dipole –Hydrogen bonds –Dispersion (London) forces

Dipole to dipole interactions Remember the polar molecules have unevenly distributed electrical charges Positive charges of one molecule attract the negative charge of another molecule: the stronger the polarity the stronger the force –The dipole to dipole forces of polar molecules are similar to the forces in crystals of ionic compounds, but they are much weaker

Hydrogen bonds A hydrogen bond is a special type of attractive interaction that exists between an electronegative atom and a hydrogen atom bonded to another electronegative atom. This type of bond always involves a hydrogen atom, thus the name.

Dispersion (London) Forces The electrostatic attraction that arises between atoms or molecules of the presence of instantaneous and induced dipoles Not a strong force, known as a weak force

The three forces Dispersion forces work between all kinds of molecules: polar and nonpolar. Dipole to dipole interactions are only between polar molecules Hydrogen bonds only exist between polar molecules that have the correct atoms (hydrogen with nitrogen, oxygen, or fluorine)

Sample problem: List the types of intermolecular forces that act between the molecules of the following compounds: a. O=C=O b. H:F c. Br:Cl Solution: __________________________________ __________________________________ __________________________________ ____________

Questions? Write down 3 questions you have so far.

Chart of three forces

Home work Read pages Write a ½ pg summary on it

Candle lab What will happen to the candle when you light it? What causes the candle to change states of matter? Why? What other objects have you noticed changes of state in? Draw pictures of your candle – Before After

Solids What are some basic properties of solids? What is the difference between table salt and carbon tetrachloride? How does the kinetic theory explain why solids have the properties they do? –Give an example: Why do solids resist compression?