Chapter 3 “Water and Life”
Key Concepts
- Polar covalent bonds in water molecules result in hydrogen bonding
- Four emergent properties of water contribute to Earth’s suitability for life
- Acidic and basic conditions affect living organisms
Hydrogen Bonding In Water
- Electrons of the polar covalent bonds spend more time near oxygen than
hydrogen
● Charge unevenly distributed; making water a polar molecule
● Polarity results in hydrogen bonds between molecules
Emergent Properties Of Water
- Four properties of water that contribute to suitable environment for life:
● Cohesive behavior
● Ability to moderate temperature
● Expansion upon freezing
● Versatility as a solvent
Cohesion Of Water Molecules
- Cohesion - Hydrogen bonds collectively hold molecules together
● Results in high surface tension
● Contributes to water transport in organisms
- Adhesion - Attraction between different substances
● Helps to counter downward pull of gravity
Co- means same, Ad- means different
Temperature Moderation By Water (Slide 1 of 2)
- Water absorbs heat from warmer air and releases stored heat to cooler air
● Absorbs or releases large amount of heat with only a slight change in its own
temperature
Temperature Moderation By Water (Slide 2 of 2)
Kinetic energy - energy in motion
● Random energy of moving atoms or molecules
Temperature - the average kinetic energy of molecules in body of matter
● Heat - thermal energy transfers from one body of matter to another
● Calorie - amount of heat required to raise temp of 1g of water 1 celsius
● Joule - 0.239 cal OR 1 cal = 4.184 J
Water’s Specific Heat
Key Concepts
- Polar covalent bonds in water molecules result in hydrogen bonding
- Four emergent properties of water contribute to Earth’s suitability for life
- Acidic and basic conditions affect living organisms
Hydrogen Bonding In Water
- Electrons of the polar covalent bonds spend more time near oxygen than
hydrogen
● Charge unevenly distributed; making water a polar molecule
● Polarity results in hydrogen bonds between molecules
Emergent Properties Of Water
- Four properties of water that contribute to suitable environment for life:
● Cohesive behavior
● Ability to moderate temperature
● Expansion upon freezing
● Versatility as a solvent
Cohesion Of Water Molecules
- Cohesion - Hydrogen bonds collectively hold molecules together
● Results in high surface tension
● Contributes to water transport in organisms
- Adhesion - Attraction between different substances
● Helps to counter downward pull of gravity
Co- means same, Ad- means different
Temperature Moderation By Water (Slide 1 of 2)
- Water absorbs heat from warmer air and releases stored heat to cooler air
● Absorbs or releases large amount of heat with only a slight change in its own
temperature
Temperature Moderation By Water (Slide 2 of 2)
Kinetic energy - energy in motion
● Random energy of moving atoms or molecules
Temperature - the average kinetic energy of molecules in body of matter
● Heat - thermal energy transfers from one body of matter to another
● Calorie - amount of heat required to raise temp of 1g of water 1 celsius
● Joule - 0.239 cal OR 1 cal = 4.184 J
Water’s Specific Heat
