Chemical Basis of LifeChapter 2

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

Periodic Table of Elements

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 – Ionic Bonds

Ionic Bond Animation

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.

Covalent Bond Animation

Water

• Polar molecule– Electronegativity– Polar covalent bonds

Chemical Bonding – Hydrogen Bonds

• Attraction between the (+) and (-) ends of a molecule

• Weak bonds

• Hydrogen = positive end

• Oxygen = negative end

Hydrogen Bonding Animation

Unique Properties of Water

• Cohesion

• Adhesion

• Resistant to temperature change

Molecular Structure• Structural formula

• Ball and stick

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

pH Scale

Chemical Reactions• Processes producing chemical changes

in matter– Reactants– Products

• Matter cannot be created or destroyed

• Energy flow

2 H2O2 2 H2O

Types of Chemical Reactions

• Oxidation-Reduction (redox)– Ex. C6H12O6 + 6O2 6CO2 + 6 H2O + ATP