Unit B- Cell Compounds

Name : ______Date : ______Chemical Compounds – WATER -Notes

Backgrounds Information: Life as we know it, is based on the chemistry of organic molecules. ______

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For example;______

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The organic molecules in living things are easily grouped into four types. An understanding of these four biochemical compounds is the purpose of the next unit.

1. ______3. ______

2. ______4. ______

Why is water so incredibly important? What happens to the quality of life if the chemical conditions of living things change?

In the formation of chemical compounds, organic or inorganic, atoms must be bond together to form stable structures. In order to do this, the electron configurations around the various nuclei in the compound must also be stable. The stability can be achieved through some degree of sharing electrons between the atoms.

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-The alternative is a very unequal sharing. ______

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- In between these two extremes is what is termed polar covalent. ______

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Water Structure of water:

In a covalent bond atoms share electrons to become stable. ______

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Any molecule that ends up with different charged regions is called a polar molecule. Hence it would be a dipole.

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- ______

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Therefore, water tends to clump together. Although the bond is weak, the vast number of these bonds gives water its unique properties.

Roles of Water 1) ______

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Since blood is mainly water, the ability of water to dissolve and transport substances greatly aids in bringing about necessary chemical reactions in the body.

2) Moderates Climate (both internal and external climates) due to high Specific Heat Capacity

- ______

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Example: Oceans keep surrounding land masses cool in summer and warmer in winter. Example: ______

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3) Liquid water is more dense than ice. (very rare for compounds).

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______. Hydrogen bonding allows molecules to come closer together.

If ice formed at the bottom, all lakes and oceans would freeze solid in the winter.

4) Water is transparent.

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5) Water molecules are cohesive.

They stick to each other and to other surfaces. This keeps surfaces moist and lubricated. ______

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Acids, Bases and Buffers

Acids are molecules that dissociate to release hydrogen ions. HCl (Hydrocholoric

Acid) is a strong acid because ______

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Bases : ______

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At pH 7, the concentration of hydrogen ions = the concentration of hydroxide ions. [ H+ ] = [ OH- ]

At pH 6 : ______pH 3 has 100 times more H+ than Ph 5

The pH scale is just a comparison between the [ H+ ] and [ OH- ].

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Most enzymes, which control the chemical reactions in your body, can only operate at certain pH levels.

Example: ______

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Buffers : ______

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- + Example: Bicarbonate (HCO3 ) absorbs excess acid (H ions)

______Note: The buffer keeps pH constant despite adding more and more acid.

Example of Buffering System

# 2 #1 ______  _____ + ______

Carbonic Hydrogen Bicarbonate Acid Ion Ion

If H+ is added, ______

If OH- is getting too high, the ______

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