1. Why is the water important for biology?
2. How does the polarity of water molecules work?
3. What are the emergent properties of water?
Water is essential for living.
All organisms are made of water and also their environments.3/4 of Earth is water and 70-95% of a cell is surrounded by water. Water can be found as solid, liquid and gas. All living organisms need water more than anything else.
The polarity of water molecules results in hydrogen bonding.
Water is composed by 2 hydrogen and 1 oxygen elements. Oxygen is more electronegative than hydrogen. It means the electrons of the covalent bonds spend more time closer to oxygen than to hydrogen. They are polar covalent bonds. The distribution is unequal.
The four emergent properties of water :
Cohesion
Moderation of Temperature
Insulation of Bodies of Water by Floating Ice
The Solvent of Life
In this picture, water behaves as if covered by an invisible film. Some animals can stand, walk or run on water without breaking the surface. This shows us the cohesion of water resulting from the collective strength of its hydrogen bonds.
5 main facts from this chapter :
. Water has a specific heat, heat is absorbed when hydrogen bonds break is released when hydrogen bonds form.
. Ice floats because it's less dense than liquid water . This allows life to exist under the frozen surfaces of lakes and polar seas.
. A water molecule can transfer an H plus to another water molecule to form H3O plus and OH minus.
. A substance that reduces the hydrogen ion concentration of a solution is called a base.
. The sphere of water molecules around each dissolved ion is called a hydration shell.
Video :
http://www.youtube.com/watch?v=QH1yphfgfFI
This third chapter is quiet harder than the first 2 chapters. It has more chemistry and chemical themes and made me get confused. In this chapter, we basically learned how the structure of a water molecule allows it to interact with other molecules.
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