Chemistry of Life

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What are some of the basic physical and chemical processes that allow energy to be stored and utilized by living things?

Chemistry of Life

 Atom – composed of  Nucleus  Proton – positive charge  Neutron – neutral charge  Electrons – orbiting nucleus, negative charge

Chemistry of Life

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Element

– a substance consisting entirely of one type of atom.

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Molecule

– two or more

atoms

joined together by a chemical bond.

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Chemical compounds

– two or more

elements

joined together (can be the same or different type of element)

Chemical bonds

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Chemical bonds

– how atoms are held together. Energy is stored in the bonds!

Types of Chemical Bonds 

Ionic bonds

: electrons are transferred  one atom (or compound) loses electron; becomes positive  one atom (or compound) gains electron; becomes negative

Salt:

NaCl  Na + + Cl Example of Ionic Bond

 Covalent bonds: electrons are

shared

between atoms to form molecules  (not as strong as ion bonds! ) Water: H 2 O Each hydrogen atom bonds with the Oxygen atom

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Hydrogen Bonding

Special type of bonding / attraction between water molecules.

 It is the reason water will “beads up” (cohesion) or climbs up sides of graduated cylinder (adhesion) to form the meniscus.

Chemical Bonds

 Van der Waals Forces - not as strong as ionic or covalent but are responsible for the Gecko’s ability to climb up a glass window

ACIDS, BASES, BUFFERS

 pH – measurement the concentration of the H+ (hydrogen ions) in solution.

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pH equal to 7: The Solution is

Neutral

ACIDS, BASES, BUFFERS

Acids:  pH is less than 7  Release hydrogen ions H + in solution  Has positive charge,  Juices, vinegar  Taste sour

ACIDS, BASES, BUFFERS

 Base  

pH greater than 7

Releases hydroxide ions OH in solution  Ex. are ammonia, some soaps, lye  Taste bitter, feel slimey ___________________

pH Scale

Buffers

 Buffers: solutions that react with acids or bases and prevent sudden changes in pH, for example

bicarbonate of soda, Tums