Upload
sherilyn-franklin
View
230
Download
0
Tags:
Embed Size (px)
Citation preview
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