1. © 2012 Pearson Education, Inc. PowerPoint ® Lecture Slides Prepared by Patty Bostwick-Taylor, Florence-Darlington Technical College C H A P T E R 2 Basic Chemistry

2. © 2012 Pearson Education, Inc. Isotopes and Atomic Weight Atomic weight Close to mass number of most abundant isotope Atomic weight reflects natural isotope variation

3. © 2012 Pearson Education, Inc. Radioactivity Radioisotope Heavy isotope Tends to be unstable Decomposes to more stable isotope Radioactivity—process of spontaneous atomic decay Used to tag biological molecules for medical imaging.

4. © 2012 Pearson Education, Inc. Text, pages 10-11 PET scan

5. © 2012 Pearson Education, Inc. Molecules and Compounds Molecule—two or more atoms of the same elements combined chemically Compound—two or more atoms of different elements combined chemically

6. © 2012 Pearson Education, Inc. Figure 2.4

7. © 2012 Pearson Education, Inc. Chemical Reactions Atoms are united by chemical bonds Atoms dissociate from other atoms when chemical bonds are broken

8. © 2012 Pearson Education, Inc. Electrons and Bonding Electrons occupy energy levels called electron shells Electrons closest to the nucleus are most strongly attracted Each shell has distinct properties The number of electrons has an upper limit Shells closest to the nucleus fill first

9. © 2012 Pearson Education, Inc. Electrons and Bonding Bonding involves interactions between electrons in the outer shell (valence shell) Full valence shells do not form bonds

10. © 2012 Pearson Education, Inc. Inert Elements Atoms are stable (inert) when the outermost shell is complete How to fill the atom’s shells Shell 1 can hold a maximum of 2 electrons Shell 2 can hold a maximum of 8 electrons Shell 3 can hold a maximum of 18 electrons

11. © 2012 Pearson Education, Inc. Inert Elements Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state Rule of eights Atoms are considered stable when their outermost orbital has 8 electrons The exception to this rule of eights is Shell 1, which can only hold 2 electrons

12. © 2012 Pearson Education, Inc. Figure 2.5a

13. © 2012 Pearson Education, Inc. Reactive Elements Valence shells are not full and are unstable Tend to gain, lose, or share electrons Allow for bond formation, which produces stable valence

14. © 2012 Pearson Education, Inc. Figure 2.5b

15. © 2012 Pearson Education, Inc. Chemical Bonds Ionic bonds Atoms become stable through the transfer of electrons Form when electrons are completely transferred from one atom to another Ions Result from the loss or gain of electrons Anions are negative due to gain of electron(s) Cations are positive due to loss of electron(s)

16. © 2012 Pearson Education, Inc. Figure 2.6

17. © 2012 Pearson Education, Inc. Figure 2.6, step 1

18. © 2012 Pearson Education, Inc. Figure 2.6, step 2

19. © 2012 Pearson Education, Inc. Figure 2.6, step 3

20. © 2012 Pearson Education, Inc. Chemical Bonds Covalent bonds Atoms become stable through shared electrons Electrons are shared in pairs Single covalent bonds share one pair of electrons Double covalent bonds share two pairs of electrons

21. © 2012 Pearson Education, Inc. Figure 2.7a

22. © 2012 Pearson Education, Inc. Figure 2.7b

23. © 2012 Pearson Education, Inc. Figure 2.7c

24. © 2012 Pearson Education, Inc. Covalent Bonds Covalent bonds are either nonpolar or polar Nonpolar Electrons are shared equally between the atoms of the molecule Electrically neutral as a molecule

25. © 2012 Pearson Education, Inc. Figure 2.8a

26. © 2012 Pearson Education, Inc. Covalent Bonds Covalent bonds are either nonpolar or polar Polar Electrons are not shared equally between the atoms of the molecule Have a positive and negative side or pole

27. © 2012 Pearson Education, Inc. Figure 2.8b

28. © 2012 Pearson Education, Inc. Chemical Bonds Hydrogen bonds Weak chemical bonds Hydrogen is attracted to the negative portion of polar molecule Provides attraction between molecules

29. © 2012 Pearson Education, Inc. Figure 2.9 Hydrogen bonds H O H H O H O H H H O H H H O (a)(b) –– ++ ++ ++ –– –– ++ –– ++ –– ++

30. © 2012 Pearson Education, Inc. Patterns of Chemical Reactions Synthesis reaction (A + B  AB) Atoms or molecules combine Energy is absorbed for bond formation Decomposition reaction (AB  A + B) Molecule is broken down Chemical energy is released

31. © 2012 Pearson Education, Inc. Figure 2.10a

32. © 2012 Pearson Education, Inc. Figure 2.10b

33. © 2012 Pearson Education, Inc. Patterns of Chemical Reactions Exchange reaction (AB + C  AC + B) Involves both synthesis and decomposition reactions Switch is made between molecule parts and different molecules are made

34. © 2012 Pearson Education, Inc. Figure 2.10c

35. © 2012 Pearson Education, Inc. Biochemistry: Essentials for Life Organic compounds Contain carbon Most are covalently bonded Includes carbohydrates, lipids, proteins, nucleic acids Inorganic compounds Lack carbon Tend to be simpler compounds Includes water, salts, and some acids and bases

36. © 2012 Pearson Education, Inc. Important Inorganic Compounds Water Most abundant inorganic compound in the body Vital properties High heat capacity Polarity/solvent properties Chemical reactivity Cushioning

37. © 2012 Pearson Education, Inc. Important Inorganic Compounds Salts Easily dissociate into ions in the presence of water Vital to many body functions Include electrolytes which conduct electrical currents

38. © 2012 Pearson Education, Inc. Figure 2.11 O H H ++ ++ –– Water molecule Na + Cl – Salt crystal Ions in solution

39. © 2012 Pearson Education, Inc. Important Inorganic Compounds Acids Release hydrogen ions (H + ) Are proton donors Bases Release hydroxyl ions (OH – ) Are proton acceptors Neutralization reaction Acids and bases react to form water and a salt

40. © 2012 Pearson Education, Inc. pH Measures relative concentration of hydrogen ions pH 7 = neutral pH below 7 = acidic pH above 7 = basic Buffers—chemicals that can regulate pH change

41. © 2012 Pearson Education, Inc. Figure 2.12

42. © 2012 Pearson Education, Inc. Chemical Reactions Dehydration synthesis—monomers or building blocks are joined to form polymers through the removal of water molecules

43. © 2012 Pearson Education, Inc. Figure 2.13a

44. © 2012 Pearson Education, Inc. Chemical Reactions Hydrolysis—polymers are broken down into monomers through the addition of water molecules

45. © 2012 Pearson Education, Inc. Figure 2.13b