In-Depth Water Properties and Theories

Learning Outcomes

  • Understanding particle theory, atom structure, and bonding explains the properties of water and its significance to marine life.

Students should be able to:

  • 1.1.1 Explain changes of state in water (solid, liquid, gas) using the kinetic particle theory.

  • 1.1.2 Describe the structure of the atom: nucleus (protons and neutrons) with electrons in shells.

  • 1.1.3 Understand that sea water is a mixture of different elements and compounds.

  • 1.1.4 Describe (use diagrams) covalent bonding in a water molecule (sharing of electron pairs).

  • 1.1.5 Identify covalent molecules (water, carbon dioxide, oxygen, sulfur dioxide, glucose) from diagrams.

  • 1.1.6 Describe (using diagrams) ionic bonding in sodium chloride (loss/gain of electrons to form ions).

  • 1.1.7 Identify ionic substances (sodium chloride, calcium carbonate) from diagrams.

  • 1.1.8 State the chemical name and formula of salts in sea water (NaCl, MgSO₄, CaCO₃).

  • 1.1.9 Explain formation of hydrogen bonds in water.

  • 1.1.10 Explain how hydrogen bonding affects water's properties: solvent action, density, specific heat capacity.

Properties of Water:

  • Importance of Water:

    • Coverage: 71% of Earth is covered with water; 97% is in oceans.

  • Oceans: Major oceans include Pacific, Atlantic, Arctic, Southern, and Indian, collectively covering approximately 70% of the globe.

Kinetic Particle Theory (KPT):

  • All matter consists of tiny particles (atoms, molecules, ions) constantly in motion.

  • The energy of particles determines their movement and interaction.

Behavior in Different States:

  • Heating: Increases particle motion (energy).

  • Cooling: Decreases particle motion (energy).

States of Matter Comparison:

State

Energy in Particles

Forces Between Particles

Arrangement of Particles

Movement of Particles

Shape

Volume

Gas

Highest

None

Far apart

Move quickly

Indefinite

Indefinite

Solid

Lowest

Strong

Close together, regular

Vibrate in place

Definite

Definite

Liquid

Moderate

Moderate

Close together, random

Move around each other

Indefinite

Definite

Water Molecule Structure:

  • Composed of 2 hydrogen atoms (H) and 1 oxygen atom (O).

  • Covalent Bonds: Hydrogen atoms bond to oxygen via covalent bonds, resulting in a polar molecule.

  • Hydrogen Bonds: Water molecules bond through hydrogen bonds, which arise from interactions between partial charges.

Effect of Hydrogen Bonds on Water Properties:

  • Universal Solvent: Can dissolve many substances due to its polarity.

  • Density: Ice is less dense than liquid water due to crystal lattice structure when frozen.

  • Specific Heat Capacity: High due to hydrogen bonds, moderates temperature (climate buffer).

Additional Properties:

  • Surface Tension: On the water surface, hydrogen bonds create a 'film'.

  • Cohesion: Water molecules attract each other (droplet shape).

  • Adhesion: Water molecules attracted to other substances (capillary action).

  • Water exists in all three states (solid, liquid, gas).