Color coded: Biochemistry of Water
Water is a Polar molecule
Because of the high electronegativity of oxygen and the low electronegativity of hydrogen, the oxygen end has a slight negative charge (-), while the hydrogen has a slight positive charge (+).
The water molecule’s shape is said to be “bent.”
This shape means that one side of the molecule “the hydrogen side” is positive, while the other side “the oxygen side” is negative.
The polar water molecules form hydrogen bonds with each other.
These bonds affect many of the biologically important properties of water.
Important Properties of Water for Biology
Water has a high specific heat.
Specific heat:The amount of heat needed to change the temperature of 1 gram of a substance by 1 degree.
Water’s specific heat is very high due to the hydrogen bonds that hold the water molecules together.
Due to its high specific heat, water is excellent for maintaining a constant internal body temperature.
Water is an excellent solvent.
Solvent:The substance dissolving the solute.
Water is often referred to as the “Universal Solvent”. This means that water is great for dissolving other materials (solutes).
Solutes:The substance being dissolved in the solvent.
Due to its polarity, water is best at dissolving salts and polar molecules.
Water has a high heat of vaporization.
Heat of vaporization:The amount of heat needed to convert a liquid to a gas.
Due to the many hydrogen bonds which hold water molecules together, the heat of vaporization is very high for water.
When the water does eventually evaporate, it carries heat away with it.
Water is cohesive and adhesive
Cohesion:A substance sticking to itself.
Adhesion:A substance sticking to another substance.
Due to its polarity, water molecules stick to each other (cohesion) and to other polar molecules (adhesion).
This property allows transpiration to move water from the ground, through the plant, and eventually out into the air.
Transpiration:The movement of water molecules throughout plants.
Water expands as it freezes
The volume of water beings to expand after it cools to temperatures below 4 degrees Celsius.
This causes ice to be less dense than liquid water; ice can float on water.
This happens because the HYDROGEN bonds force the chains of water molecules further apart as the molecules cool down and slow down; this increased volume causes a decrease in density.
Water is a Polar molecule
Because of the high electronegativity of oxygen and the low electronegativity of hydrogen, the oxygen end has a slight negative charge (-), while the hydrogen has a slight positive charge (+).
The water molecule’s shape is said to be “bent.”
This shape means that one side of the molecule “the hydrogen side” is positive, while the other side “the oxygen side” is negative.
The polar water molecules form hydrogen bonds with each other.
These bonds affect many of the biologically important properties of water.
Important Properties of Water for Biology
Water has a high specific heat.
Specific heat:The amount of heat needed to change the temperature of 1 gram of a substance by 1 degree.
Water’s specific heat is very high due to the hydrogen bonds that hold the water molecules together.
Due to its high specific heat, water is excellent for maintaining a constant internal body temperature.
Water is an excellent solvent.
Solvent:The substance dissolving the solute.
Water is often referred to as the “Universal Solvent”. This means that water is great for dissolving other materials (solutes).
Solutes:The substance being dissolved in the solvent.
Due to its polarity, water is best at dissolving salts and polar molecules.
Water has a high heat of vaporization.
Heat of vaporization:The amount of heat needed to convert a liquid to a gas.
Due to the many hydrogen bonds which hold water molecules together, the heat of vaporization is very high for water.
When the water does eventually evaporate, it carries heat away with it.
Water is cohesive and adhesive
Cohesion:A substance sticking to itself.
Adhesion:A substance sticking to another substance.
Due to its polarity, water molecules stick to each other (cohesion) and to other polar molecules (adhesion).
This property allows transpiration to move water from the ground, through the plant, and eventually out into the air.
Transpiration:The movement of water molecules throughout plants.
Water expands as it freezes
The volume of water beings to expand after it cools to temperatures below 4 degrees Celsius.
This causes ice to be less dense than liquid water; ice can float on water.
This happens because the HYDROGEN bonds force the chains of water molecules further apart as the molecules cool down and slow down; this increased volume causes a decrease in density.
