3.2 Water Flashcards
When do covalent bonds occur?
When atoms share electrons
What does polar molecules have in terms of charge?
Regions of negativity and regions of positivity
What is a hydroxyl group? What is its symbol?
1 Hydrogen bonded to 1 Oxygen (OH)
Describe the properties of Hydrogen bonds. Refer them to water.
Weak interactions
Occur in high numbers
Constantly break + reform in water molecules
What are the properties of water?
- High boiling point
- Lighter than O2 and CO2
- Liquid at room temp due to H bonds
- Takes lots of energy to evaporate water + to raise its
temp
What happens to water when it freezes?
Becomes less dense due to the H bonds formed
- What happens to water below 4°C?
2. What does this result in?
- H bonds fix positions of polar molecules further apart
than average distance in liquid state - Produces a giant, rigid open structure
Why does ice float?
Less dense than water
Why is water said to have cohesive properties?
Moves as one mass bc molecules are attracted to each other (cohesion)
Why is water said to have adhesive properties?
Water molecules are attracted to other materials
*e.g. when you wash your hands, water sticks to them, it doesn’t just run off
Why does water have a skin of surface tension?
Water molecules are more cohesive to each other than
to air
Describe the role of water in terms of: acting as a solvent.
Give examples.
Due to its polarity, water is a solvent which solutes in an organism can dissolve in
E.G. cytosol of prokaryotes + eukaryotes is mainly water
Describe the role of water in terms of: acting as a medium
Medium for chemical reactions
Helps transport dissolved compounds in + out of cells
Describe the role of water in terms of: acting as a transport medium
- Due to cohesion, molecules stick together when water
is transported through the body - Adhesion occurs between water molecules + other polar molecules
-Combo of adhesion + cohesion = water displays capillary action
What is capillary action?
When water rises up a narrow tube against gravity
