Chemistry

1. Chemistry • Composition of Matter • Energy • Solutions

2. The Chemical Context of Life

4. Composition of Matter • Matter • Elements • Atoms • Compounds

5. Learning Objectives • Define element, atom, compound, & molecule • Draw a model of the structure of an atom • Explain what determines an atom’s stability • Contrast ionic & covalent bonds

6. Elements, Atoms, & Chemical Bonding • To View Video: • Move mouse cursor over slide title-link • When hand appears, click once • ASX Video plays about 5 min

7. Composition of Matter • Matter • Anything that occupies space & has mass: - quantity of matter in an object • Element: • A pure substance that cannot be broken down chemically into simpler kinds of matter

8. Periodic Table of the Elements Elements of organic molecules Important ions / metals Trace elements 118 Discovered

9. Periodic Table:Symbols & Numbers Atomic Number Element Symbol 1 5 Element Name 2 3 Atomic Mass # 6 Energy Shell Valence Electrons 4

10. Most Common Elements In Living Tissues Note: # e- matches # p+ Note: how e- fill energy levels

11. Elements of Living Things S P O N C H U H X I A Y L O Y T R D F S G R B R U P E O O O R H N G N G O E E R N N U S

12. Atomic Structure: Nucleus Proton / positive charge / plus sign • Atom: • The smallest particle of an element that still retains all the properties of that element • Nucleus: • protons: p+ • neutrons: n0 Neutron / neutral charge/ no sign

13. Atomic Structure & Terminology • Atomic Number: • # of protons (p+) • Atomic Mass Number: • # of protons (p+) + # of neutrons (n0) • Energy Levels (Shells): • electrons: e- • orbitals: regions where electrons orbit the nucleus e- in “highest “energy levels have the most energy

14. Compounds • Compound: • A pure substance made up of atoms of 2 or more elements in a fixed ratio • Chemical Reactions: • Elements combine in ways that cause their atoms to become stable • Chemical bonds are broken, atoms are rearranged, & new attachments are formed

15. Why do atoms undergo chemical reactions? • Atoms that have unfilled outer energy levels form bonds with other atoms to become stable • H & He need 2 e- to fill outer shell • C, O, N, P, S, Na, Ca, K, Cl, I, etc need 8 e-to fill outer shell

16. Chemical Bonding • Covalent Bond: • Sharingof 1 or more pairs of electrons between atoms • Strong chemical bond: valence shells merge

17. Compounds & Molecules • Kinds of Compounds: • Ionic compounds – ionic bonding • Molecular compounds – covalent bonding • Molecule: Requires covalent bonding • The simplest part of a substance that retains all the properties of that substance & exists in a free state

18. Chemical Bonding • Ionic Bond: • Transferof 1 or 2 e- from one atom to another forming ions • Cations are +; anions are - • Oppositely charged ions attract one another • Weak chemical bond: valence shells do not merge

19. Ionic Bonding • To View Video: • Move mouse cursor over slide title-link • When hand appears, click once • ASX Video plays about 1 min

20. Ionically Bonded Compounds form Crystal Lattices

21. Molecules & Compounds Not all compounds are molecules Not all molecules are compounds

22. Types of Compounds • Molecular compounds • Covalently bonded atoms Ex: H2O (water) is a molecular compound consisting of H & O in a 2:1 ratio • Ionic compounds • Ionically bonded atoms Ex: NaCl (table salt) is an ionic compound consisting of Na & Cl in a 1:1 ratio

23. Chemical Bonding • To View Video: • Move mouse cursor over slide title-link • When hand appears, click once • ASX Video plays about 18 min • Program contains a video quiz

24. Energy • Energy & Matter • Energy & Chemical Reactions

25. Learning Objectives • List the 3 states of matter, and explain how matter can change state • Describe how energy changes are involved in chemical reactions • Explain how enzymes affect chemical reactions in organisms • Explain what a redox reaction is

26. Energy & Matter • Energy: • The ability to do work or cause change • Forms of energy: • Radiant energy (light) • Thermal energy (heat) • Chemical energy (stored & usable) • Electrical energy (stored & usable) • Mechanical energy • One form of energy can be converted to another form • Free Energy: • The energy in a system available to do work • Biological systems are OPENsystems

27. Energy Conversion Stored Chemical Energy Radiant Energy < Heat > Usable Chemical Energy of ATP

28. Free Energy Change in position Movement cross membrane Chemical breakdown

29. Work:Closed & Open Systems

30. Energy in Living Things Kinds of Work Done by Cells

31. States of Matter • All atoms & molecules in any substance are in constant motion • Exception – absolute zero = 0 oK or -273 oC • The rate of motion determines the state of matter: • Solid • Liquid • Gas

32. Three States of MatterCoexist on Earth Gas Liquid Solid

33. Phases (States)of Matter • Solids: • Little particle motion – vibrate in place w/ strong mutual attraction • Fixed volume & shape • Liquids: • Moderate particle motion – move freely w/ moderate mutual attraction • Fixed volume taking the shape of the container • Gases: • Rapid particle motion – move rapidly w/ little or no mutual attraction • Unfixed volume filling the container they occupy

34. Phase Changes in Matter Phase changes occur when thermal energy isadded toorremoved fromthe substance in its current phase.

35. Energy& Chemical Reactions • Reactants: • Combine to form products • Left side of typical chemical equation • Products: • Formed from reactants • Right side of typical chemical equation

36. Chemical Reaction Notation A + B AB reactant + reactant --yields product CO2 + H2O H2CO3

37. Reversible Reactions A + BAB CO2 + H2OH2CO3 Equilibrium: the rate of formation of AB from A + B is equal to the rate of formation of A + B from AB.

38. Energy& Chemical Reactions • Exergonic Reactions: • Release energy • Can occur spontaneously • Decomposition: breakdown of more complex molecules into simpler ones • Endergonic Reactions: • Absorb energy • Do NOT occur spontaneously • Synthesis: formation of more complex molecules from simpler ones

39. Energy Transfer:Exergonic Reaction C6H12O6+6O2  (sugar) (oxygen gas) 6CO2+ 6H2O+Energy(carbon (water)(ATP) dioxide) Example: Cellular Respiration

40. Energy Transfer:Endergonic Reaction 6CO2+ 6H2O+Energy  (carbon (water)(from sunlight) dioxide) C6H12O6+6O2 (sugar) (oxygen gas) Example: Photosynthesis

41. Energy Flow & Chemical Cycling

42. Activation Energy • Activation Energy: • Amount of energy needed to begin any chemical reaction • Necessary for both exergonic & endergonic reactions • Used to break bonds in the reactants so that new bonds can form to make the products

43. Reaction Energy Profile Activation energy

44. Activation Energy Barrier & Enzymes • Catalyst: • Chemical substances that reduce the amount of activation energy needed for a reaction to occur • Enzymes: • Catalyst proteins in living things • Specific for particular chemical reactions

45. Enzyme Function

46. Chemical Reactions & Energy • To View Video: • Move mouse cursor over slide title-link • When hand appears, click once • Mov Video plays about 2 min

47. Enzymes & Activation Energy • To View Video: • Move mouse cursor over slide title-link • When hand appears, click once • Mov Video plays about 2 min

48. Reduction – Oxidation:Redox Reactions • Reduction = gain of e- • the reduced molecule is an oxidizing agent • electron acceptor • Oxidation = loss of e- • the oxidized molecule is a reducing agent • electron donor

49. Redox Reaction X-2e- + Y X + Y-2e-

50. Transfer of Electrons& Energy Release 2