chemical basis of life chapter 2. chemistry matter is made up of separate chemical components...
Post on 22-Dec-2015
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TRANSCRIPT
Chemistry
• Matter is made up of separate chemical components– Chemistry = Interactions between
atoms/molecules
Sub-cellular concepts
• Matter
• Atoms
• Elements
• Natural elements– About 25 essential for life– H,O,N,C = 96% of human body– Trace elements
Atomic Structure• 3 Basic subatomic particles.
– Proton– Electron– Neutrons
• Atomic Number
• Atomic Mass
Isotopes
• different forms of same element.
• Same number of Protons, but different mass
• Radioactive Isotopes
Electrons (e-)
• Arranged in shells
• Valence
Hydrogen (H)Atomic number = 1
Electron
Carbon (C)Atomic number = 6
Nitrogen (N)Atomic number = 7
Oxygen (O)Atomic number = 8
Outermost electron shell (can hold 8 electrons)
First electron shell (can hold 2 electrons)
• Reactivity
Chemical Bonding – Ionic Bonds
• Form between Ions of opposite charge
• NaCl– One atom gives up e- (cation).– One atom recieves e- (anion).– Results in filled outer shells for both.
Chemical Bonding: Covalent Bonds
• Result from electron sharing.– 1 or more pairs of outer shell electrons.– Number of possible bonds = number
needed to fill outer shell.
Chemical Bonding – Hydrogen Bonds
• Attraction between the (+) and (-) ends of a molecule
• Weak bonds
• Hydrogen = positive end
• Oxygen = negative end
More Definitions
• Solutions– Solvent– Solute
• Aqueous solution = Water is the solvent– Water = Universal solvent– Results from the Polarity
pH (potential of Hydrogen)
• H2O dissociates into H+ and OH- (hydroxide) ions– Acids– Bases
• pH scale
Chemical Reactions• Processes producing chemical changes
in matter– Reactants– Products
• Matter cannot be created or destroyed
• Energy flow
2 H2O2 2 H2O