Essential idea: Water is the medium of life.
The cohesive nature of nature gives it surface tension. The surface tension in turn allows organisms such as pond skaters (above) to move across the surface. For pond skaters the surface of water is their habitat. The surface tension transmits vibrations from fallen invertebrates - this allows pond skaters to detect and locate their prey.
Understandings, applications and skills:
| 2.2.U1 | Water molecules are polar and hydrogen bonds form between them. |
| 2.2.U2 | Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water. [Students should know at least one example of a benefit to living organisms of each property of water. Transparency of water and maximum density at 4°C do not need to be included.] |
| 2.2.U3 | Substances can be hydrophilic or hydrophobic. |
| 2.2.A1 | Comparison of the thermal properties of water with those of methane. [Comparison of the thermal properties of water and methane assists in the understanding of the significance of hydrogen bonding in water.] |
| 2.2.A2 | Use of water as a coolant in sweat. |
| 2.2.A3 | Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water. |
[Text in square brackets indicates guidance notes]
Starter
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A rapid fire introduction from Hank Green
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Learn by discovery
Investigate to find about the properties of water by Tom Edwards Drawing and annotating hydrogen bonding in water molecules Use the video to both learn and test yourself |
Presentation and notes
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The presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.
Vocabulary
Correct use of terminology is a key skill in Biology. It is essential to use key terms correctly when communicating your understanding, particularly in assessments. Use the quizlet flashcards or other tools such as learn, scatter, space race, speller and test to help you master the vocabulary.
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Below are the notes for this topic. Alternatively the 2.2 Water bottom line template can be used as a note construction template in itself or as a checklist if you are using your own or another template such as the Cornell style template.
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Weblinks
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Hydrogen bonding
H-bonds in water, from Northland College The temporary nature of hydrogen bonds in water by St Olaf College Drawing the structure of water molecules by Stephanie Castle Polarity of water by Click4Biology Properties of water Properties of water by Sunamas Inc. Properties of water, from Northland College Molecule polarity simulation from PhET Labs (allow Java to run) Solubility in water simulation from PhET Labs (allow Java to run) _The thermal, cohesive and solvent properties of water by Stephanie Castle The relationship between the properties of water and it's uses by Stephanie Castle Cohesion in water by Click4Biology Thermal properties of water by Click4Biology Solubility and transport by water Water as a solvent by Click4Biology Dissolving, from Northland College Dissolving NaCl from PreparatoryChemistry PhET Labs: Salts and Solubility and also Dissolving Sugars and Salts |
The surface tension of water demonstrated on the ISS
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Nature of science:
Use theories to explain natural phenomena—the theory that hydrogen bonds form between water molecules explains the properties of water. (2.2)
Theory of knowledge:
Claims about the “memory of water” have been categorized as pseudoscientific. What are the criteria that can be used to distinguish scientific claims from pseudoscientific claims?
This BBC article discusses could water really have a memory?
Below is a humorous look at Homeopathy by Mitchell and Webb
This BBC article discusses could water really have a memory?
Below is a humorous look at Homeopathy by Mitchell and Webb
