Basic Chemistry Water Acids, Bases and pH Cell Compounds Basic Chemistry Water Acids, Bases and pH

Basic Chemistry Organic versus Inorganic Compounds Organic compounds are the basis of all living things – those present in living organisms are grouped into four types All compounds are made of bonded atoms Covalent Bonds, Polar Covalent, Ionic Bonds Atoms bond to become more stable – through sharing electrons. Different degrees of sharing result in different bonds. Polar molecules have dipoles where there are regions of positive and negative areas.

Water All living things depend on water Inorganic, Covalent, Polar O H Negative dipole O H Positive Dipole

Water Hydrogen Bonding: attractive forces between adjacent water molecules O H δ- δ+ O H δ- δ+ O H δ- δ+

High Heat Capacity Excellent Solvent Transparent Water Hydrogen Bonding gives water some very important properties. High Heat Capacity Excellent Solvent Transparent Greatest Density at 4˚C Cohesive Lubricant

Acids and Bases

Acids Acids are molecules that dissociate to release hydrogen ions (H+) Strong acids such as hydrochloric acid dissociate easily: HCl → H+ + Cl- Weak acids dissociate to a much lesser extent H2O → H1+ + OH1-

Bases Bases are molecules that release hydroxide ions (OH1-) Bases combine with Acids to neutralize them H1+ + Cl1- + Na1+ + OH1-→ H2O + NaCl

pH A measure of the amount of free H1+ -log[H1+] Range of 1-14 7 is neutral < 7 is acidic and >7 is basic In organisms pH is very important Buffers help to maintain pH by binding with excess hydrogen or hydroxide ions

In Review Organic Compounds will be examined throughout this course. Inorganic Compounds like acids, bases and water are important in living systems. Hydrogen Bonding gives water many properties that make it significant in all living things.

Homework For each property of water – explain what the property is and how it is important in living systems. Describe dehydration synthesis and hydrolysis For each of the following compounds provide an example and draw its structure. a) Carbohydrate b) Lipid c) Protein d) Nucleic Acid