CHAPTER 2:  BASIC CHEMISTRY

 

I.  Matter: anything that has mass and volume

 

A.  Solid, liquid or gas

B. Elements: basic unit of matter that can't be broken down by chemical  means (92)

1.      Symbols: C, H, N, O, P, S, (most common in life) Na, Mg, Al, Si, Cl, K, Ca, F

2.      Atoms: smallest part of an element that acts like that element

a. Protons: positive charge, in the nucleus

b. Neutrons: neutral charge, in the nucleus

c. Electrons: small, negative charge

3.      Atomic weight: number of protons and neutrons in an atom, ex) C=12

4.  Atomic number: number of protons (and electrons) in an atom, ex) C=6

 

C.  Isotopes: have a different number of neutrons, often radioactive, ex) C14

 

D. Chemical Properties

1.  Energy: the ability to do work

a.  Kinetic energy: energy of motion

b.  Potential energy: stored energy

2.      Electron shells, orbitals, or energy levels (Bohr model) where  electrons are

 

3.      located

a.  1st level: 2 electrons (spherical orbital)

b.  2nd level: 8 electrons (spherical, 3-D dumbbell shaped, x,

    y, z)

c.  Octet rule: the outer shell is most stable when it is filled

d.  The number of electrons in the outer shell determine

     whether atoms react with each other

3.  Chemical Formulas: set proportion of elements, ex) H2O

4.  Equations: represent a chemical reaction,

     ex) C6H12O6 + 6 O2 -> 6 H2O+ 6 CO2

 

II. Compounds: 2 or more different elements bond together ex) H20

A.     Molecule: the smallest part of a compound that has properties of that

     compound, ex) O2, H2O

B.  Opposite charges attract in ionic bonding

1.  Ions: charged particle, ex) H+ (lost 1 electron)

a. Anion: negative charge, ex) Cl- (electron acceptor)

b. Cation: positive charge, ex) Na+ (electron donor)

2.  Ionic bond: positive and negatives ions attract, ex) Na+Cl-

C.  Covalent Bonds: atoms share electrons equally, C-C

1.  Double covalent: O=O, stronger bond

2.  Nonpolar: equal sharing of electrons, ex) CH4

3.  Polar: molecule results in uneven charge distribution, ex) H2O

4.  Hydrogen bonds: weak bond that holds slightly polar molecules

    together, ex) DNA, water clings together, shown by a dotted line,

    easily  broken

D.  Reactions in Cells (LEO says GER)

1.  Oxidation: loss of electrons

2.  Reduction: gain of electrons

III.  Water is essential to life (70-90% water)

 

A.  Universal solvent (dissolves), facilitates chemical reactions

B.     Adheres (clings to surfaces) and is cohesive (clings together), makes it

     good for transporting nutrients, and wastes

C.  Resists changes in temperature

D.  Resists change of state (from liquid to ice and from liquid to steam)

E.  Less dense as ice than as liquid water

F.  Hydrophilic, attracted to water; hydrophobic, repelled by water

G.  High surface tension, ex) water strider

IV.  Acids and Bases: narrow range in living systems

 

A.  Water ionizes: H2O <-> H+ + OH-

B.  pH Scale: 0-6 acid, 7 neutral, 8-14 base

C.  Acids: ionic compound that releases H+, ex) lemon juice

D.  Bases: ionic compound that releases OH-, alkaline, ex) ammonia

E.  Buffers: neutralize acids and bases; acid + base -> salt + H2O

F.     Problems caused by acid rain

I.  The Mole

            A.  The mole is defined as the number of carbon 12 atoms in 12 grams of

                  carbon 12.

 

            B.   The number of atoms in 12 grams of carbon 12 atoms corresponds to

                   Avogadro's Number, which is 6.02 * 1023.

 

            C  Amadeo Avogadro was a 19th century chemist (1776-1856)

 

            D.  The name "Avogadro's Number" is just an honorary name attached to

                  the calculated value of the number of atoms, molecules, etc. in a

                  mole of any chemical substance.

 

            E.  1 mole (of any substance) = 6.02*1023 atoms, molecules, or ions

                 (depending on how that substance exists at that time.) (For example, 1

                  mole of Na+ ions has 6.02*1023 Na+ ions in it.)

 

            F.  1 mole (of any substance) = the total of the elements atomic masses

                  expresses in grams. (For example, 1 mole of Na weighs 23 grams.)

 

II.  Oxidation-Reduction Reactions

 

            A.  Oxidation is the loss of electrons

 

            B.  Reduction is the gain of electrons

 

            C.  Oxidation and reduction always takes place at the same time because

                 one molecule accepts the electrons given up by another molecule.

 

            D.  In living things, hydrogen ions often accompany electrons.  Therefore,

 

                        1.  Oxidation is a loss of hydrogen atoms (e- + H+).

 

                        2.  Reduction is a gain of hydrogen atoms.

 

Reduction

energy + CO2 + 2H20 ® (CH20) + H20 + O2

Oxidation

 

                        3.  When hydrogen atoms are transferred from water to carbon

                             dioxide, glucose is formed.

 

                        4.  Water has been oxidized and carbon dioxide has been reduced.

 

                        5.  The oxidation states are numbers that allow us to keep track of

                             the electrons in each element.

 

                            Oxidation State:             +4            2(-2)®            0                      0

 

                        6.  Oxidation is the increase in oxidation numbers. Reduction is

                              exactly the opposite. It is the reduction in oxidation numbers.