1. The properties of water are essential to all life on Earth. a. Outline the significance of the labeled parts of this diagram, showing the attraction between three water molecules.
| Negative charge oxygen atom
| Positive charged oxygen atom
| Weak hydrogen bond between δ+ and δ- parts of neighboring water molecules.
| Strong hydrogen bond
| Slight negative charge as large oxygen atom attracts shared electrons closer to itself than the hydrogen atom.
Extension: at this point you might want to consider how ionic and covalent bonding work, in order to really understand how the slight positive (δ+ ) and slight negative (δ- ) charges are generated. 2. Water has many properties which are essential for life. Complete the table below.
| Significance to living things
| When a solid changes to a liquid and a gas more heat is added. This is quite hard as to change phases you have to break the hydrogen bonds and it takes a lot of energy to change from one phase to another.
| Water’s thermal properties means that it has the ability to cool us down. When sweat evaporates off our body it takes heat away from our body.
| Water’s polar nature makes water “sticky”. This happens because the water molecules stick together due to the hydrogen bonds.
| If water were not “sticky” water would not form droplets. In addition, cohesion allows plants to transpire and pull water up to the leaves.
| Solvent Properties
| Again due to water’s polar nature water is known as the “universal solvent” and as a result is it good at dissolving substances. Polar substances are hydrophilic and non-polar substances are hydrophobic.
| Water’s solvent properties mean that it can transport waste through veins and arteries. It enables trees to transport gases and solutes as well.
| (include uses as a coolant, medium for metabolic reactions, transport medium)
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