1. Basic Chemistry for Biology Atomic Structure and the Backbone of Life

2. List three states of matter and how they change. Define element, atom, compound and molecule. Identify the importance of ions and isotopes within a biological system. Draw a model of the structure of an atom. Explain what determines atomic stability. Relate the formation of ionic and covalent bonds to the stability of atoms. Identify the elements necessary for all life. Discuss several reasons why carbon is considered to be the backbone of all life. Define acids and bases and relate their importance to biological systems. Objectives At the conclusion of this unit students will be able to…

3. Three States of Matter Solid Liquid Gas Evaporation Sublimation Condensation Melting Point Freezing Point Boiling Point Critical Thinking Living things need a constant supply of energy, even though many of the chemical reactions they undergo release energy. Why is this true?

4. THINK – PAIR – SHARE Turn to your neighbor & discuss the following terms… Atom vs. Element Compound vs. Molecule

5. Elements Necessary for All Life The Basic 6 –Sulfur –Phosphorous –Oxygen –Nitrogen –Carbon –Hydrogen SPONCH Other Elements –Iron –Magnesium –Potassium –Calcium –Manganese –Chlorine –Zinc –Sodium –Selenium

6. Atomic Model of Carbon Atomic Number = 6 Atomic Mass = 12 Number of Protons = 6 Number of Neutrons = 6 Number of Electrons = 6 Thinking Critically A fluorine atom has nine electrons. Make an energy level diagram for fluorine. How many electrons would be needed to fill its outer level?

7. Forms of Pure Carbon Graphite Coal Diamond C 60 (Buckminster-fullerenes)

8. Why is CARBON the Backbone of all LIFE? To be stable it has to make 4 covalent bonds Carbon can bond with other carbon atoms or other atoms. It can make single, double, triple bonds They can form straight chains, branched chains or ring structures.

9. Types of Bonds formed by Carbon

10. Ions vs. Isotopes Ions Gain or lose electrons Ions can cross membranes Examples –Ca ++ muscles –Na + thinking –K + muscles Isotopes Gain or lose neutrons Used to trace pathways through the body. Examples –Carbon-14 used for carbon dating Half-life of C-14 is 5,730 years –Barium used for x-rays

11. What determines if something is an acid or base? pH – percentage of Hydrogen pH Scale – the pH scale ranges from 1-14 with 7 being neutral. Acids – any substance that produces a hydrogen ion (H + ) in water. Base – any substance that produces a hydroxide ion (OH - ) in water.

12. Types of Chemical Bonds Ionic Bonds: weak bonds formed when metals transfer electrons to nonmetals. –How are ionic bonds held together? Covalent Bonds: a stronger bond that is formed when two non-metals share electrons. Their valence shells overlap. Hydrogen Bonds: a weak ionic bond formed between hydrogen and fluorine, oxygen, and nitrogen. Types of Chemical Bonds

13. Polar vs. Ionized: Molecules can have ends that contain charges without gaining or losing electrons –Polar molecules exist because atoms share electrons unevenly based on electronegativity –Ionic compounds will gain or lose electrons leaving different parts of their molecules with different charges. Polarized vs. Ionic

14. Water: the cradle of life Polar molecule A universal solvent: it will dissolve all other polar molecules through Hydrogen bonding High Specific Heat Capacity Water: the cradle of Life!

15. Water cont’d Water Ionizes: breaks down into H+ and OH - Hydrophobic/Hydrophilic: –Phobic: water fearing (non-polar) –Philic: water loving (polar) Cohesion/Adhesion: –Co: water sticking to water –Ad: water sticking to other polar molecules Water cont’d

17. Acids Compounds that form H + when dissolved in water –H+ is called a hydrogen ion –Example: HCL ------- > H + + Cl - Hydrogen Ion Have a pH of 0-6.9 Known as H + donors

18. Bases Compounds that form OH - when dissolved in water –OH- is known as a hydroxide ion –Example: NaOH -------- > Na + + OH - Hydroxide ion Have a pH of 7.1-14 Known as H + acceptors

19. pH of Chemical Reactions Most chemical reactions occur at pH values between 6-8 –Changes in the pH can have deadly effects on the organism Acid rain can change the pH of soil and destroy crops or other organisms (run-off into lakes and streams) One place the pH is very acidic is the stomach (ph 1.5-3.5) –Enables food to be broken down

20. Buffers Any fluid that resists a change in pH Resist change by either accepting or donating protons –Example: Human blood Why?

21. Review Questions Answer each of the following questions in your notes. What information is contained in a chemical formula? Describe the structure of an atom. Why do all isotopes of an element have the same properties? How are they different? What is a compound? Using the structure of a water molecule, explain why water is polar. What does pH measure?