Science Notes
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. | w. | Negative charge oxygen atom | | x. | Positive charged oxygen atom | | y. | Weak hydrogen bond between δ+ and δ- parts of neighboring water molecules. | | z. | Strong hydrogen bond | | δ- | Slight negative charge as large oxygen atom attracts shared electrons closer to itself than the hydrogen atom. | | δ+ | |
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.
| Explanation | Significance to living things | Thermal Properties | 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. | Cohesion | 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)
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.
| Explanation | Significance to living things | Thermal Properties | 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. | Cohesion | 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)