CHAPTER 6: THE CHEMISTRY OF LIFEWHAT YOU WILL LEARN:

1. You will relate the structure of an atom to how it interacts with other atoms.

2. You will explain how water is important to life.

3. You will compare the role of carbon compounds in organisms.

WHY IT’S IMPORTANT:

• Living organisms are made of simple elements as well as complex carbon compounds. With an understanding of these elements and compounds, you will be able to relate them to how living organisms function.

6.1 Atoms and their InteractionsBoth living and nonliving things are

composed of the same basic building blocks called Atoms

I. Elements Substance that can’t be broken down

into simpler chemical substances. 90 naturally occurring elements

A. Natural elements in living things Only about 25 of the natural

occurring elements are essential to living organisms.

Four out of the 90 make up 96% of a human (1) Carbon (2) Hydrogen

(3) Oxygen

(4) Nitrogen

• B. Trace Elements

• Elements found in living things in very small amounts

• Plants obtain trace elements by absorption

• Animals get their trace elements by eating

II Atoms: The Building Blocks of Elements. The smallest part of an Element that has the characteristics of that Element.• A. The structure of an atom• The center of the Atom the Nucleus made of

positively charged protons and particles that have no charge - Neutrons.

• Forming a cloud around the outside are negatively charged Electrons.

• B. Electron energy levels• Electrons travel around the Nucleus in

certain regions known as energy levels

• The first level is the smallest it hold only two electrons

• The second level is larger, it can hold 8 electrons

• The third can hold 18 electrons.

• Atoms contain equal numbers of electrons and protons

III. Isotopes of an Element

• Atoms of the same element that have different numbers of Neutrons are Isotopes

• C12 C13 C14

• Isotopes such as C12 tend to break apart – they are radioactive

Atoms of the same element that have different numbers of Neutrons are Isotopes C12 C13 C14 Isotopes such as C12 tend to break apart – they are radioactive• A. How covalent bonds form• Atoms combine to become more stable

• Atoms like to have their outer energy shell filled

• Elements can fill their outer shell by sharing electrons.

• A covalent bond is make by sharing electrons

• A molecule is a group of Atoms held together by covalent bonds. H2O

• B. How Ionic Bonds Form

• An Atom that has lost or gained an electron becomes charged thus it is an ion Na + Cl-

• The attractive force between two atoms of the opposite charge is an ionic bond

• Less abundant in living things than Covalent bonds but, still very important ---sodium/potassium ions for nerve impulses and calcium ions for muscle contractions.

V. Chemical Reactions Chemical reactions occur when bonds are

formed or broken All the chemical reactions in an organism are

referred to as Metabolism – breaking down and building up

• A. Writing chemical equations

• Reactants – undergo chemical reactions H + O

• Products – substances formed by chemical reactions H2O,Table sugar C12H22O11, glucose C6H12O6

VI. Mixtures and Solutions A mixture is a combination of substances in which the individual components retain their own properties Sand/Sugar A solution is a mixture in which one or more substances (solute) are distributed evenly in another (solvent) Kool – Aid

• A. Acids and Bases• Chemical reactions can occur only when

conditions are right.• Temperature• Energy • pH

The pH is measure of how acid or basic a solution is.Scale 0 7 14Acid Neutral Base H+ 0H-

6.2 Water and Diffusion• I. Water and its Importance• Most life processes can occur only when molecules

and ions are free to move and collide with one another• Water allows movement.

• A. Water is polar• A polar molecule is a molecule with

unequal distribution of charge. • O-• H+ H+• Water attracts to water

• Hydrogen bonds - attractions between hydrogen and oxygen

• Capillary action• B. Water resists temperature changes• Water is like an Insulator helps maintain

a steady environment

• C. Water expands when it freezes• Ice on ponds• Ice breaking rocks

II. Diffusion Particles of matter are in constant motion, colliding with each other.• A. Early observation: Brownian motion • Brown – pollen grain in water • Dye particles• B. The process of Diffusion

• The net movement of particles from area of high concentration to areas of low concentration.

• Slow process because it relies on random molecular motion.

• Key factors: Concentration

• Temperature

• Pressure

• C. Diffusion in living systems

• The difference in concentrations of a substance across space is called Concentration Gradients.

• Diffusion is one way cells move things in and out of the cell (air/blood)

6.3 Life Substances “you are what you eat”

• I. Role of Carbon in Organisms

• Single bond shares 1 pair of electrons

• Double bond shares 2 pairs of electrons

• Triple bond shares 3 pairs of electrons

• Carbon--because of its 4 outer electrons can form:

• Straight chains

• Branched chains

• Rings

• Compounds that have the same simple formula (what and how much) but different structures are Isomers

• A. Molecular Chains• Carbon compounds vary in size from two

carbons to thousands

• A polymer is a large molecule formed when many smaller molecules bond together.

• Condensation - water is removed from two smaller molecules that have H+ and an OH-

• Hydrolysis - Polymers are broken apart by the insertion of a water molecule

• B. The Structure of Carbohydrates

• Contain C H O 2H to 1O

• Monosaccharides – simple sugar • ( glucose and fructose)

• Disaccharide – two monosaccharide linked together. • ( sucrose)

• Polysaccharide – polymers composed of many monosaccharides. ( starch, glycogen, and cellulose )

C. The structure of Lipids Contain C H O called fats and oils

Used for energy storage, insulation and protective coatings.

• D. The structure of Proteins• Contain C H O N

• Basic building blocks of protein are amino acids.

• 20 common amino acids

• Peptide bonds hold amino acids together to form proteins

• Proteins are the building blocks of our bodies

• Proteins called Enzymes control the rate of many chemical reactions within the body

• E. The structure of Nucleic acids• Consist of Carbon, Hydrogen, Oxygen, and Nitrogen• Made of smaller units called NUCLEOTIDES

• A Nucleotide has three groups of molecules:

• Five carbon sugar

• A phosphate group

• A base