Bonds• Ionic• Covalent• Hydrogen

Bonds

Ionic• Transfer electrons• Form between ions

(+/-)

Covalent• Share electrons• Weaker than ionic

• 2 types– Polar– Nonpolar

Polar Bonds

• Unequal distribution of charge• Water molecule

Nonpolar

• Equal sharing of electrons

Hydrogen bonds

• Attraction between positive hydrogen portion of one molecule…

• And negative portion of a second molecule

• Water molecules are bonded by hydrogen bonds

Properties of Water

• Cohesion– Attractive force–Holds together– Due to H-bonding– ex: water sticking to

other water molecules-meniscus

Properties of Water

• Surface tension• Related to

cohesion• Due to H-

bonds• Cause water

to be pulled down into liquid

• “skin” on top of the water

• Water striders• http://www.yo

utube.com/watch?v=KSLUwmJOo_M

Properties of Water

• Adhesion– Attractive

force between two different surfaces

– Ex: Water molecules and glass molecules

Properties of Water

• Capillary action• Raising of liquid• Glass tube, water

will rise automatically

Acids and Bases

Acids:

• Taste sour

• Contains H+, (the more H+, the stronger the acid)

• Very reactive

Properties of Bases:

• Taste bitter

• Contains OH- (the more OH-, the stronger the base)

• Slippery when wet

Acids and Bases

• If the number of H+ ions in a solution is greater than number of OH- ions than the solution is an acid

• If the OH- ions are greater than the H+ ions than the solution is a base

pH Scale

• Ranges from 0-14• Numbers 0-6 represent acids• 7 is neutral• Numbers 8-14 represent bases

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

strongest acid strongest base

pH ScaleAs you move from pH 0 to pH 14, the

concentration of H+ DECREASES (10 times each number)

As you move from pH 0 to pH 14, the concentration of OH- INCREASES (10 times each number)

Ex: A substance with pH3 is 100 times stronger acid than a substance with pH 5. A substance with pH 8 is 100 times weaker base than a substance with pH 10.

Buffer

• Neutralize acids or bases • Keep the pH from large changes