Chemistry: Atoms, Bonds, and Compounds

Gulf of Mexico's Dead Zone

• Nutrient-rich runoff causes plankton blooms and hypoxia (low oxygen levels).
• Hypoxia kills or displaces marine organisms, impacting fisheries and the fishing industry.
• US government and farmers debate reducing fertilizer use.
• Distance between nitrogen/phosphorus source and dead zone can complicate management.

Atoms and Elements

• Atoms are the basic unit of matter.
• Nucleus contains protons and neutrons.
• Electrons move around the nucleus.
• Elements are substances that cannot be broken down into other substances.
• There are 94 naturally occurring and 24 artificially created elements.

Bonding

• Atoms combine by bonding.
• Covalent bonds involve shared electrons.
• Ionic bonds involve transferred electrons.
• A molecule is two or more atoms joined by covalent bonds.
• A compound is a substance composed of two or more different elements.

Organic and Inorganic Compounds

• Organic compounds primarily have covalently bonded carbon and often include hydrogen.
• Hydrocarbons are organic compounds containing only hydrogen and carbon.
• Inorganic compounds lack carbon-carbon bonds.

Solutions

• A mixture is a combination of elements, molecules, or compounds that are not bonded chemically.
• Solutions are mixtures with uniformly distributed ingredients.
• Mixtures can be solids, liquids, or gases.

Macromolecules

• Large organic compounds essential for life.
• Proteins perform various functions, including enzyme activity.
• Nucleic acids (DNA & RNA) control protein production.
• Carbohydrates provide energy and structure (sugars, starch, cellulose).
• Lipids (fats, waxes, hormones) are not soluble in water.

Water

• Water is essential for all living organisms.
• Hydrogen bonding gives water unique properties.
• Cohesion allows water to resist temperature changes.
• Water is less dense as a solid than a liquid.
• Water can dissolve many molecules.

Acids, Bases, and pH

• Water molecules separating into ions (H⁺ and OH⁻) creates acidic, basic, or neutral solutions.
• The pH scale measures acidity or basicity.
• A pH of 7 is neutral.
• A pH below 7 is acidic, with a high concentration of H⁺.
• A pH above 7 is basic, with a high concentration of OH⁻.

Interacting Systems

• Earth's interconnected systems use energy, information, and matter.
• Negative feedback loops stabilize systems, like thermoregulation in humans.
• Predator-prey cycles are an example of negative feedback.
• Positive feedback loops drive systems to extremes.

Spheres of Function

• Earth's systems are divided into spheres based on location and function.
• Geosphere: Earth's rocks and minerals.
• Lithosphere: Crust and uppermost mantle; includes tectonic plates.
• Asthenosphere: Soft middle mantle, heated by outer core.
• Lower mantle: Solid rock.
• Hydrosphere: Earth's water.
• Atmosphere: Earth's gases.
• Biosphere: Interacting living and nonliving things.

The Geosphere

• The geosphere consists of rocks and minerals.
• Crust: Earth's outer rocky layer.
• Mantle: Hot, mostly solid layer beneath the crust.
• Core: Inner and outer core, including molten metal.

Plate Tectonics

• Crust and mantle are divided into tectonic plates.
• Lithosphere: Crust and uppermost mantle, divided into tectonic plates.
• Asthenosphere: Soft, heated middle mantle.
• Convection currents in the asthenosphere move tectonic plates.
• Plate collisions/separation create landforms.
• Divergent, transform, and convergent are three major plate boundary types.

Divergent and Transform Plate Boundaries

• Divergent boundaries: Magma rises, pushing plates apart, creating new crust .
• Transform boundaries: Plates slip past each other, causing earthquakes.

Convergent Plate Boundaries

• Convergent boundaries: Plates collide, causing subduction (one plate slides under another) or mountain building.

The Biosphere and Atmosphere

• Biosphere: The part of Earth that contains living and nonliving things interacting.
• Atmosphere: Contains gases essential for life, including oxygen and greenhouse gases.

The Hydrosphere

• The hydrosphere consists of Earth's water (mostly salt water).
• Fresh water is a small portion (0.5%) of total water and usable for drinking and irrigation.
• Earth's fresh water includes surface water and groundwater.

The Water Cycle

• The continuous movement of water through the Earth's environment.
• Involves evaporation, transpiration, precipitation, runoff, infiltration, uptake, and groundwater.

Nutrient Cycling

• Matter cycles through the environment.
• Matter is transformed, not created or destroyed.
• Nutrients are essential for life processes.
• Nutrients circulate in biogeochemical cycles.

The Carbon Cycle

• Cycles carbon through the environment.
• Involves photosynthesis, cellular respiration, combustion, and the ocean-atmosphere exchange.
• Includes the roles of producers, consumers, and decomposers.

The Phosphorus Cycle

• Cycles phosphorus through the environment.
• Involves weathering, erosion, runoff, uptake by plants, and return to the soil and ocean.
• Includes the roles of producers, consumers, and decomposers.
• Humans add fertilizers and detergents affecting phosphorus distribution.

The Nitrogen Cycle

• Cycles nitrogen through the environment.
• Involves fixation, nitrification, denitrification, and other processes driven by organisms and human activities.
• Includes the roles of producers, consumers, and decomposers.
• Humans influence nitrogen cycling through fossil fuel combustion, agriculture, and industrial emissions.