Chapter 2: Chemical Basis of Life (A & P 1)

Chemistry

the branch of science that deals with the composition and characteristics of chemicals

Matter

Anything that takes up space and has weight (mass).

Elements

Smallest units of matter with specific chemical properities

Atoms

Smallest unit of an element; made of protons, nuetrons and electrons.

Ions

Atoms that gain or lose electrons, becoming charged.

Atomic Structure

• Nucleus - Contains protons (+) and Neutrons (0)

• Electrons (-) - Orbits nucleus in shells

• Atomic # - Number of protons

• Mass # - protons and neutrons

Isotopes

Same atomic number, different mass number.

Some are radioactive and emit energy

Ionic Bonds

Transfer electrons; single, double, triple bonds

Covalent Bonds

Atoms share electrons; single, double, triple bonds

Polar Covalent Bonds

Unequal electron sharing = polar molecule

Hydrogen Bonds

Weak attractions between polar molecule

Molecule

Two or more bonded atoms

Compound

Molecule with different elements

Molecular Formula

C6H12O6 (glucose), H2O

Structural Formula

Shows arrangement of atoms

Types of Chemical Reactions

• Synthesis

• Decomposition

• Exchange

• Reversible

  • Catalysts (enzymes)

Synthesis Reaction

small —> large (growth)

Decomposition

Large —> small (digestion)

Exchange reaction

Bonds break and rearrange

Reversible

Products revert to reactants

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Catalysts (Enzymes)

Speed up reactions

Electrolytes

Release ions into water

Acids

Release H+ ions

Bases

Combine with H+ ions

pH Scale

7 = Neutral

less than 7 = Acid

above 7 = Basic

Buffers

Stabilize pH by combining with excess H+ or OH+

Inorganic Compounds

• Water

• Oxygen

• Carbon Dioxide

• Salts

Organic Compounds

• Lipids

• Proteins

• Nucleic Acids

• ATP