1.1 Particle Theory and Bonding

1.1 Particle Theory and Bonding

• All matter contains particles in constant motion, even if just vibrating.
• The energy of these particles determines their motion and state (solid, liquid, gas).
• Changes in energy lead to changes in state:
  • Melting (solid to liquid): Adding energy makes particles vibrate faster, breaking apart from each other and flowing.
  • Evaporation (liquid to gas): Heating a liquid gives particles more energy, making them move faster and further apart until they evaporate.
  • Boiling: A specific temperature (100°C at 1 atm) where liquid rapidly turns to gas.
  • Condensation (gas to liquid): Cooling a gas causes particles to lose energy, slowing down and coming together to form a liquid.
  • Freezing (liquid to solid): Cooling a liquid causes particles to lose energy, becoming closer together and forming the structure of a solid.

1.1.2 Atom Structure

• Atoms have a nucleus with protons (positive) and neutrons (neutral).
• Electrons (negative) orbit the nucleus in shells.
• The first shell holds two electrons, and subsequent shells can hold up to eight (octet rule).
• Atoms are most stable when their outermost shell is full.
• Atomic number = number of protons in an atom.

1.1.3 Mixtures and Compounds

• Seawater is a mixture of different elements and compounds.
• Nearly every element is found in the ocean, usually combined as compounds.

1.1.4 Covalent Bonding

• Covalent bonds involve sharing of electron pairs between non-metal atoms.
• These bonds are strong because they complete the outermost electron shells of the atoms involved.
• Water molecules form a covalent bond through sharing.

1.1.5 Covalent Molecules

• Water (H₂O): Needed for photosynthesis.
• Oxygen (O₂): Needed for respiration.
• Carbon Dioxide (CO₂): Needed by plants for photosynthesis.
• Sulfur Dioxide (SO₂): Needed by bacteria for chemosynthesis.
• Glucose (C₆H₁₂O₆): Produced by photosynthesis.

1.1.6 Ionic Bonding

• Ionic bonds occur when atoms gain or lose electrons to create charged ions.
• Opposites attract: Positive ions (cations) bond with negative ions (anions).
• Salts are formed from ionic bonds (e.g., sodium chloride).

1.1.7 and 1.1.8 Ionic Substances and Salts in Seawater

• Ionic substances include sodium chloride (NaCl), magnesium sulfate (MgSO₄) and calcium carbonate (CaCO₃).
• These are common salts found in seawater.

1.1.9 and 1.1.10 Hydrogen Bonding in Water

• Hydrogen bonds form between polar molecules (like water) due to uneven electron sharing.
• Water's polarity allows it to dissolve many ionic and polar substances.
• Water has high specific heat capacity, meaning it absorbs or releases a lot of heat without a significant temperature change.
• Water's density properties help regulate temperature in the environment by the low density of ice.
• Hydrogen bonding is crucial for water's properties (high boiling point, solubility, and ice floating).

1.2 Solubility in Water

• Solvent: A substance capable of dissolving other substances.
• Solute: A substance that can be dissolved.
• Solution: A mixture of solute and solvent.
• Dissolution: The process of dissolving.
• Solubility: How much solute can dissolve in a given amount of solvent.
• Salinity: Concentration of dissolved salts in seawater (measured in parts per thousand, ppt).
• Salinity affects the freezing point of water.
• Temperature and pressure affect the solubility of salts and gases in water.

1.2.6 Surface Runoff, Precipitation, and Evaporation

• Precipitation (rain, snow) lowers salinity by adding water.
• Evaporation increases salinity by removing water.
• Surface runoff can affect salinity with fresh water (dilution) or salts (increase)

1.2.7 pH Scale

• pH measures the concentration of hydrogen ions (H⁺) in a solution.
• The pH scale ranges from 0 to 14.
• Acidic solutions have a pH less than 7.
• Neutral solutions have a pH of 7.
• Alkaline (basic) solutions have a pH greater than 7.

1.2.8 Measuring pH

• Litmus paper, universal indicator, and pH probes can be used to measure pH.

1.2.9 Oxygen Solubility in Water

• Temperature and salinity affect oxygen solubility.
• Warmer temperatures and higher salinity reduce oxygen solubility.
• Increased depth increases pressure which increases oxygen concentration
• The solubility of CO2 is high.

1.2.10 Factors Affecting Gas Solubility in Water

• Factors like temperature, pressure, atmospheric pressure and salinity all play a role in impacting gas solubility.

1.3 Density and Pressure in Water

• Water temperature affects density (warmer water is less dense).
• Salinity affects density (higher salinity increases density).
• Pressure increases density.
• Density differences create water layers (e.g., thermocline, halocline).
• Ice floats because it is less dense than liquid water; this prevents the entire water body from freezing.

1.3.4 Importance of Floating Ice

• Ice acts as a thermal insulator.
• This prevents the entire body of water from freezing.
• Allows marine organisms to live.

1.3.5 Temperature and Salinity Gradients in Water

• Gradients in temperature and salinity create distinct water layers (e.g., surface layer, thermocline, halocline).
• These layers influence mixing and circulation.