1. The Chemical Context of Life
Unit 2
Chapter 2

2. Matter Anything that takes up space and has mass Affected by gravity
Consists of elements and compounds

3. Element Compound “pure” substance
Can’t be broken down to another substance
Periodic table
Compound
2 + different elements combined in a fixed ratio
Ex. H2O, NaCl

4. Elements of Life 20-25% essential elements
O, C, N, and H make up 96% living matter
4% : P, S, Ca, K & trace elements
required in minute quantities
(ex: Fe, I)

5. Atoms and Molecules Atoms Mass Location Charge neutron 1 nucleus
Subatomic particles
Mass
(dalton or AMU)
Location
Charge
neutron 1
nucleus
proton +1
electron
negligible
shell -1

6. Isotopes # neutrons varies, but same # of protons
Radioactive isotopes used as tracers (follow molecules, medical diagnosis)
Uncontrolled exposure causes harm

7. Strongest Bonds Ionic: 2 ions (+/-) bond (givers/takers) Na+Cl-
affected by environment

8. Ionic bond

9. Covalent: sharing of e-
Polar: covalent bond between atoms that differ in electronegativity
Unequal sharing of electrons
Nonpolar: e- shared equally
O2 or H2

10. Covalent bond

11. Weaker Bonds
Hydrogen: H of polar covalent molecule bonds to electronegative atom of other polar covalent molecules

12. Bonds Covalent Ionic Hydrogen All important to life
Form cell’s molecules
Quick reactions/ responses
H bonds to other electronegative atoms
Strong bond
Weaker bond (esp. in H2O)
Even weaker
Made and broken by chemical reactions

13. Function is related to shape
Similar shapes = mimic
morphine, heroin, opiates mimic endorphin (euphoria, relieve pain)

14. Chemical Reactions Reactants  Products
6CO2 + 6H2O  C6H12O6 + O2
Chemical equilibrium: point at which forward and reverse reactions offset one another exactly
Reactions still occurring, but no net change in concentrations