Water and Life on Other Planets

1) Identify molecular structure and physical and chemical properties of water.

2) Describe how water's structure explains its properties.

3) Explain water's role in living things.

1) The molecular structure of water consists of a single oxygen covalently bonded to two hydrogen atoms. The physical properties of water includes it's appearance,color, odor and taste. It also includes the boiling point and freezing point of water. The chemical properties of water includes solubility, adhesion, cohesion, surface tension, specific heat capacity, heat of vaporization etc.

2) Water is polar in nature. Therefore, it forms hydrogen bonds. This gives water it's unique properties such as a relatively high boiling point, high specific heat, cohesion, adhesion and density.

3) Water is very much necessary for the survival of living organisms. Water also aids in the digestion process.

Step-by-step explanation

1) Structure of water molecule:

• One water molecule is made up of 2 hydrogen atoms and 1 oxygen atom. They are bonded by polar covalent bonds.
• The 2 hydrogen atoms and 1 oxygen atomis arranged in a non-linear shape.

Physical properties of water:

• It is colorless, tasteless, odorless, and transparent in its pure liquid state.
• It boils at 100°C and water freezes at 0°C.
• It can exist in all three physical states, i.e., solid, liquid, or gas.
• Density of water increases as its temperature decreases until it reaches 4°C. Water is unique because its density begins to decrease as the temperature decreases to 0°C.

Chemical properties of water:

• Water is an universal solvent.
• Water is a polar molecule.
• Water is a stable substance due the sharing of electrons between the hydrogen and oxygen by covalent bonding.
• Water has a high heat of vaporization.
• Its polarity results in high surface tension and adhesion.
• Cohesion of water creates liquid state. It also creates bonding between hydrogen and oxygens between neighboring atoms. This allows the insects to walk on water.
• Water has high specific heat. Therefore, it takes a long time to change its temperature.

2) The molecular structure of water plays a significant role in determining its properties. It is a polar molecule. Hence, it is able to form multiple hydrogen bonds. This accounts for many of water's unique properties such as a relatively high boiling point, high specific heat, cohesion, adhesion and density.

3) Role of water in living things:

• It is necessary for the survival of organisms.
• It acts as a medium for the metabolic process of cells.
• Water is also necessary for the synthesis of many biological molecules.
• Water helps in maintaining a stable internal temperature.
• It provides effective transport medium i.e., blood, vascular tissue in plants etc.