Chapter 5: Water and Seawater
• Water has many unique properties, both chemical and physical.
• Salts and other dissolved compounds in seawater. • Ocean water salinity, temperature, and density vary with depth.

Water's structure defines its many properties
• Atoms – building blocks of all matter
• Subatomic particles
– Protons
– Neutrons
– Electrons

• Number of protons distinguishes chemical elements Water is a molecule
• Strong covalent bonds between one hydrogen (H) and
(two) oxygen (O) atoms
• A single molecule of water is stable. • H20 is dipolar
– Bent shape gives water its unique properties

• Dipolar nature leads to molecules attracting each other Hydrogen Bonding
• Polarity results in attraction between molecules. • Also, attraction to ions in water. Hydrogen Bonding
• Hydrogen bonds are weaker than covalent bonds but strong enough to contribute to:
– Cohesion

– High surface tension

Hydrogen Bonding
-High solubility of compounds in water

-Unusual thermal properties of water

-Density of water

Water as a solvent
• Water molecules attract other polar molecules.
• This attraction produces an ionic bond.
• Water can dissolve almost anything – universal solvent Water’s thermal properties
• Water in all three phases is present at the Earth’s surface. • Water moderates the Earth’s heat budget.

Heat, Freezing and Boiling Points
• Heat – energy that is transferred
• Temperature – average kinetic energy of molecules in a substance
• Freezing point (also melting point): 0°C
• Boiling point (condensation point): 100°C
• Freezing and boiling points of water are unusually high

Water’s Heat Capacity and Specific Heat
• Heat Capacity – ratio of heat absorbed to the change in temperature • Water has a high heat capacity – can take in or lose much heat without changing