1. 2. 3. How are the chemical properties and reactivity of an element related to atomic valence configuration? At the subatomic level, what is a covalent bond? What four elements are the principal atomic constituents of biological molecules, and how do they differ in terms of their covalent interactions? 4 What is meant by the term electronegativity? How does electronegativity affect the properties of any given covalent bond? Compare the relative electronegativities of the four principal atomic constituents of biological molecules, and relate that property to the formation of polar versus non-polar covalent bonds between them. 5. 6. What drives the formation of stable ions? Why is a sodium ion more stable chemically than the sodium atom? 7. At the subatomic level, what is an ionic bond? 8. What is a hydrogen bond? Is it more similar to an ionic bond or a covalent bond? Why? 9. Why is it accurate to depict water as “sticky” molecules? 10. At the molecular level, what explains water’s cohesive and adhesive properties? How is this related to the existence of sequoias that are hundreds of feet tall? At the molecular level, what explains water’s high specific heat and heat of vaporization (compared to similarly sized non-polar substances)? How is this related to the relative stability of earth’s temperature and our ability to moderate temperature changes in our bodies? At the molecular level, what explains the fact that unlike most substances, frozen water is less dense than liquid water? How is this related to Earth’s fitness for life? At the molecular level, what explains the fact that water is an excellent solvent? Why is this important in a biological context? 11. 12. 13. BIO204-Unit 1 Vocabulary and Study Questions 14. In aqueous solution, why are covalent bonds more stable than ionic bonds? In other words, why will ionic compounds dissociate into constituent ions, but molecular compounds do not dissociate readily into constituent atoms? 15. What determines if a compound is hydrophilic or hydrophobic? 16. At the molecular level, explain what is meant by the term “like dissolves like 17. What happens when a water molecule dissociates? 18. What two chemical moities associate to re-form a water molecule? 19. What is meant by the dynamic equilibrium of association/dissociation in pure water? 20. What number determines the pH of an aqueous solution, and why is this 7 for pure water? 21. What happens when an acid dissociates, and how does this affect the hydrogen ion/hydroxide ion concentrations in 22. 23. What chemical characteristics cause a substance to dissociate a hydrogen ion? What happens when a base is added to an aqueous solution, and how does this change the hydrogen ion/hydroxide ion concentrations in the solution? What is a “weak acid,” and why is it weak relative to a “strong acid”? Using carbonic acid/bicarbonate as an example, explain what happens in a buffered system when the concentration of hydrogen ion or hydroxide ion is increased 24. 25.