CHAPTER 2THE CHEMISTRY OF LIFE

I. The Nature of Matter A. Atoms – the basic unit of matter; made up of 3 subatomic particles

1. Proton – found in the nucleus, positive charge 2. Neutron – also found in the nucleus, no charge

3. Electron – are in constant motion in the space around the nucleus, negative charge

B. Elements & Isotopes 1. Element consists of one type of atom, 100+ known, 1 or 2 letter symbol

2. Isotope- atoms of an element with a different # of neutrons, some are radio- active (unstable nuclei)

3. Chemical Compounds – 2 or more elements combined in definite proportions

a.NaCl - chemical formula for table saltb. Sodium (Na) is a silver metal & chlorine is a green gas

c. Salt is a white solid with different properties from either of the elements it is comprised of

4.Chemical Bonds – atoms in compounds are held together by bonds involving the valence electrons

                                                                                                

         

a.Ionic bond – one atom (Na) transfers an electron to another (Cl)

b. Covalent bond – atoms share electrons

                                                                

         

c.Van der Waals Forces – a slight attraction between

oppositely charged

portions of nearby molecules

Why does ice float?

II. Properties of Water A. The Water Molecule (H2O)

1. Polarity – water is polar because of the uneven distribution of electrons between the O and the H, the

O end is slightly – and the H end is slightly + 2. Hydrogen bonds- weaker, up to 4 bonds possible at once, this is responsible for adhesion and cohesion

B. Solutions & Suspensions 1. 2 types of mixtures can be made with water a. Solution Ex. salt in H20

Na & Cl ions areattracted by the polar H20 molecules & become dispersed(H20 is the solvent & salt is the solute)

b. Suspensions – some materials don’t dissolve but separate into pieces small enough not to settle out

C. Acids, Bases, & pH 1. pH scale - gives concentration of H+ ions; range 0-14

http://www.google.com/imgres?imgurl=http://bcn.boulder.co.us/basin/data/BACT/info/pH.gif&imgrefurl=http://bcn.boulder.co.us/basin/data/BACT/info/pH.html&h=325&w=350&sz=25&hl=en&start=69&tbnid=6737057KFcWYYM:&tbnh=111&tbnw=120&prev=/images%3Fq%3DpH%2Bscale%26start%3D60%26ndsp%3D20%26svnum%3D10%26hl%3Den%26lr%3D%26safe%3Dactive%26sa%3DN

2. Acids – a compound that forms H+ ions in solution; pH below 7

3. Bases – forms hydroxide (OH-) ions in solution; pH above 74. Buffers – cells need pH 6.5- 7.5; buffers

prevent too muchchange in pH

III. Carbon Compounds A. Chemistry of C 1. C can bond with many elements including other C, has 4 valence electrons

B. Macromolecules 1. Formed by polymerization, a process of mono- mers joining to make polymers

Glucose

Starch

Carbohydrates

2. Carbohydrates a. Made up of C, H, and O in a ratio of 1:2:1 b. Used by living things as their main source of energy

c. Composed of monomers of sugars which can combine into starch polymersd. Single sugars= monosaccharide's starch=polysaccharide

3. Lipids a. Composed of C and H b. Known as fats, oils, and waxes c. At least 1 C-C double bond makes a fat unsaturated

4. Nucleic Acids a. Contain H, C, O, N, and P b. Monomers called nucleotides c. Store and transmit genetic information

DNA

5. Proteins a. Contain N, C, H, and O b. Have an amino group(NH2) & a carboxyl group (COOH)

c. Amino acids (20+) are the monomers which make up the protein polymerd. Protein uses 1) Control the rate of reactions

2) Regulate cell processes3) Form bones & muscles4) Transport substances5) Fight disease