Chemistry Review

Radioactivity If an atom is unstable, there may be a spontaneous release of material from the nucleus as it decays Half-Life= rate of decay (the time it takes for ½ of the original amount to decay) Environmental Significance: Damages the DNA of living organisms Nuclear Energy/ Chernobyl/ Fukishima

Ionic Bond Definition Notes Examples Bond between a metal and a non-metal Transfer of electrons Notes Ions will dissociate in water Examples NaCl

Covalent Bond Definition Notes Examples Bond between two non-metals Shared electrons Notes will not dissociate in water Examples Sugar, methane

Hydrogen Bond Definition Notes Example Not really a bond but an attractive force between molecules Notes hydrogen bonding responsible for special properties of water Example Water, bases of DNA

Surface Tension Definition Environmental significance Cohesion of water molecules at the surface Attraction between the water molecules Environmental significance Aquatic insects can sit on the surface of water

Capillary Action Definition Environmental Significance Adhesion of water molecules to another surface Water may be able to move upward Environmental Significance Movement of water up stems of plants and trees

Heat Capacity Definition Environmental Significance Water is slow to change temperature Environmental Significance Organisms are not exposed to extremes Regulates climate

Freezing Expansion Definition Environmental significance Water expands when it freezes Therefore, solid is less dense than liquid and floats Environmental significance Ice forms on top of the lake creating an insulating barrier keeping heat trapped under the ice---beneficial to aquatic organisms

Solvent Definition Environmental Significance Water is the universal solvent Environmental Significance This allows for nutrient, minerals, compounds to be transported throughout the cell Pollutants are also dissolved and then distributed through water systems

WHY?? Water is POLAR! Hydrogen bonding occurs!

pH Notes

Definitions pH is the logarithmic expression of the hydrogen ion (H+) concentration Acids are compounds that release hydrogen (H+) ions in a solution Bases are compounds that release hydroxide (OH-) ions in a solution.

pH Scale

Environmental Significance Living organisms function best at a neutral (7) or slightly alkaline (7.5) pH. Strong acids and bases can interfere with biological processes of living organisms. Acids leach toxic metals from the soil—creating toxic conditions for organisms

pH Scale

Environmental Scientists Measure the pH of- Soil Water (lakes, oceans, rivers) Rain It is an abiotic factor that significantly impacts the biotic world!

The BIG question! What is the difference between the numbers on the pH scale? How much more acidic is a substance with a pH of 2 versus 3? 10X What is the difference between a pH of 4 and 8? 10,000X

Carbohydrates Elements---CHO ROLE---energy Sugars are created by photosynthesis

Lipids Elements- CHO ROLE: stored energy, cell membrane, hormones

Proteins Elements----CHON ROLES--- building blocks is amino acids tissues, enzymes, cellular transport

Nucleic Acids Elements---CHNOPS DNA- RNA----transfer genetic information