2.1.2 Water Flashcards
Draw and label 2 water molecules bonded together
H-O-H
Strong hydrogen bonds
What is a hydrogen bond?
A weak interaction that occurs when a negatively charged oxygen atom is bonded to a positively charged hydrogen atom.
What can water do due to being a liquid at room temperature?
- provide a habitat for living things
- form a major component of tissues in living organisms
- provide a reaction medium for chemical reactions
- be an effective transport medium e.g in blood and vascular tissue
Why does water have a high boiling and melting point?
The numerous strong forces of attraction between molecules (hydrogen bonds) mean more energy is required in order to break the forces of attraction and allow the molecule to move more and change state.
What are molecules that are attracted to water called?
Give examples of this type of molecule.
Hydrophilic
Sodium chloride, glucose
Why won’t water dissolve non-polar molecules?
Because they don’t have a region of charge therefore the molecule can’t be split up as there is no part of the molecule to be attracted to the charges in water.
What are molecules that aren’t attracted to water called?
Give examples of this type of molecule.
Hydrophobic
Fats and cholesterol, oxygen
What is the 1st of 7 properties of water?
What does this property mean?
How is this important/ useful?
- High specific heat capacity.
- Means that water can absorb or lose a large quantity of heat before the temperature of the water changes.
- This is useful as it provides constant and stable living conditions for water organisms. Also, constant water conditions helps to maintain homeostasis inside cells and means that enzyme-controlled reactions happen properly.
What is the 2nd of 7 properties of water?
What does this property mean?
How is this important/ useful?
- Water has a high latent heat of vaporisation
- this means that a large amount of energy is required to change the water from a liquid to a gas
- this is useful because when organisms get too hot, the evaporation of water of the surface through sweating, panting or transpiration acts as an efficient cooling effect and cools the organism down
What is the 3rd of 7 property of water?
What does this property mean?
How is this important/ useful?
- Water as ice has a lower density then liquid water
- this means that when water freezes due to a drop in temperature, a layer of ice forms of the surface of the water and floats, insulating the water beneath it. This is because each water molecule forms 4 hydrogen bonds to other water molecules, making a spaced out lattice shape which is less dense then water.
- this is really useful as it means organisms living in bodies of water have a stable environment throughout winter because they can still move and the water is insulated by the ice. The ice also provides a habitat for animals such as polar bears. Also water has a high density, meaning it can support organisms by the up-thrust it exerts.
What is the 4th of 7 property of water?
What does this property mean?
How is this important/ useful?
- Water creates surface tension.
- Water molecules at the surface don’t have any water molecules to bond to above it, therefore they exhibit stronger attractive cohesive forces to the molecules surrounding them. This creates a barrier on the surface called surface tension.
- this is very useful for small insects such as pond skaters as it provides a habitat for them.
What is the 5th of 7 property of water?
What does this property mean?
How is this important/ useful?
- Water is a universal solvent.
- This means water can dissolve a lot of other polar molecules
- This is useful because it means sessile animals and mussels etc can eat the dissolved substances as food
What is the 6th of 7 property of water?
What does this property mean?
How is this important/ useful?
- Water is transparent
- This means that water lets light completely pass through it
- this is useful for under water plants such as coral or seaweed as they can still receive light which they then use for photosynthesis to make food
What is the 7th of 7 property of water?
What does this property mean?
How is this important/ useful?
- Water can travel against gravity in a process called capillary action.
- this means that through the cohesion between water molecules, and the adhesion between the water molecules and the walls of the xylem, the water can travel upwards, delivering water to the entirety of the plant.
- this is useful as it means the water is serving as a transport medium and can sufficiently transport water to the rest of the plant
What is meant by the term polar molecule?
Water has 2 opposite charge ends of the molecule, the oxygen being slightly negatively charged and the hydrogen being slightly positively charged.
