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AP Biology Class notes from Dr. George's class turned into a study guide on Chemistry of life.
Basics
Everything is made up of matter |
Only 25 elements are essential for life |
Matter is made up of atoms |
96% of living matter is N,H,C,O |
Atoms consist of protons, Neutrons, and Electrons |
4% of living matter is Ca,K,S,P |
Bonding Properties
Electron Effects- |
determine chemical behavior of atom |
depends on the # of the electrons in the outermost shell called the "valance electrons" & "Valance shell" |
atoms want a complete octate (8 valance electrons) except for hydrogen (wants 4) |
Chemical Reactivity
Atoms tend to complete a partially filled valance shell or empty a partially filled valance shell. |
This drives reactions & completes bonds |
Bonds in chemistry
Strong Bonds |
Weak Bonds |
Covalent Bond -> share electrons evenly |
Hydrogen Bond -> attraction between + and - |
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Ionic |
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Covalent Bonds
Why are covalent bonds so strong? |
Multiple covalent bonds |
* 2 atoms share a pair of electrons |
* Double Bonds ex: O2 |
* both atoms are holding on |
* 2 Pairs of electrons |
* Very stable |
* Triple bonds ex: N2 (very strong) |
* Forms Molecules ex: H2O |
* 3 pairs of electrons |
Polar vs Non Polar Covalent Bonds
Polar Covalent |
Non-Polar Covalent |
No areas of + or - because electrons are shared evenly |
Electrons are shared unequally by atoms |
Ex: Hydrocarbons (Methane CH4) |
Ex: (H2O) -> O is more - and pulls electrons away from the H making O have a - charge. |
Balanced and stable |
Hydrogen Bonding
Attraction between +H in one H2O molecule and the -O in another H2O molecule |
Weak Bond |
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