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Basic Chemistry

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  1. Basic Chemistry

  2. Matter and Energy • Matter—anything that occupies space and has mass (weight) • Energy—the ability to do work • Chemical • Electrical • Mechanical • Radiant

  3. Composition of Matter • Elements—fundamental units of matter • 96% of the body is made from four elements • Carbon (C) • Oxygen (O) • Hydrogen (H) • Nitrogen (N) • Atoms—building blocks of elements

  4. Atomic Structure • Nucleus • Protons (p+) • Neutrons (n0) • Outside of nucleus • Electrons (e-) Figure 2.1

  5. Atomic Structure of Smallest Atoms Figure 2.2

  6. Identifying Elements • Atomic number—equal to the number of protons that the atom contains • Atomic mass number—sum of the protons and neutrons

  7. Isotopes and Atomic Weight • Isotopes • Have the same number of protons • Vary in number of neutrons Figure 2.3

  8. Isotopes and Atomic Weight • Atomic weight • Close to mass number of most abundant isotope • Atomic weight reflects natural isotope variation

  9. Radioactivity • Radioisotope • Heavy isotope • Tends to be unstable • Decomposes to more stable isotope • Radioactivity—process of spontaneous atomic decay

  10. Molecules and Compounds • Molecule—two or more like atoms combined chemically • Compound—two or more different atoms combined chemically Figure 2.4

  11. Chemical Reactions • Atoms are united by chemical bonds • Atoms dissociate from other atoms when chemical bonds are broken

  12. 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

  13. Electrons and Bonding • Bonding involves interactions between electrons in the outer shell (valence shell) • Full valence shells do not form bonds

  14. 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

  15. 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

  16. Inert Elements Figure 2.5a

  17. 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 Figure 2.5b

  18. Chemical Bonds • Ionic bonds • Form when electrons are completely transferred from one atom to another • Ions • Charged particles • Anions are negative • Cations are positive • Either donate or accept electrons

  19. Ionic Bonds + – Cl Na Cl Na Sodium atom (Na)(11p+; 12n0; 11e–) Chlorine atom (Cl)(17p+; 18n0; 17e–) Sodium ion (Na+) Chloride ion (Cl–) Sodium chloride (NaCl) Figure 2.6

  20. Ionic Bonds Cl Na Sodium atom (Na)(11p+; 12n0; 11e–) Chlorine atom (Cl)(17p+; 18n0; 17e–) Figure 2.6, step 1

  21. Ionic Bonds Cl Na Sodium atom (Na)(11p+; 12n0; 11e–) Chlorine atom (Cl)(17p+; 18n0; 17e–) Figure 2.6, step 2

  22. Ionic Bonds + – Cl Na Cl Na Sodium atom (Na)(11p+; 12n0; 11e–) Chlorine atom (Cl)(17p+; 18n0; 17e–) Sodium ion (Na+) Chloride ion (Cl–) Sodium chloride (NaCl) Figure 2.6, step 3

  23. Chemical Bonds • Covalent bonds • Atoms become stable through shared electrons • Single covalent bonds share one pair of electrons • Double covalent bonds share two pairs of electrons

  24. Examples of Covalent Bonds Figure 2.7a

  25. Examples of Covalent Bonds Figure 2.7b

  26. Examples of Covalent Bonds Figure 2.7c

  27. Polarity • Covalently bonded molecules • Some are non-polar • Electrically neutral as a molecule • Some are polar • Have a positive and negative side Figure 2.8

  28. Chemical Bonds • Hydrogen bonds • Weak chemical bonds • Hydrogen is attracted to the negative portion of polar molecule • Provides attraction between molecules

  29. Hydrogen Bonds Figure 2.9

  30. 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. Synthesis and Decomposition Reactions Figure 2.10a

  32. Synthesis and Decomposition Reactions Figure 2.10b

  33. 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. Patterns of Chemical Reactions Figure 2.10c

  35. Biochemistry: Essentials for Life • Organic compounds • Contain carbon • Most are covalently bonded • Example: C6H12O6 (glucose) • Inorganic compounds • Lack carbon • Tend to be simpler compounds • Example: H2O (water)

  36. Important Inorganic Compounds • Water • Most abundant inorganic compound • Vital properties • High heat capacity • Polarity/solvent properties • Chemical reactivity • Cushioning

  37. 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. Dissociation of a Salt in Water Figure 2.11

  39. 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. 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 Figure 2.12

  41. Important Organic Compounds • Carbohydrates • Contain carbon, hydrogen, and oxygen • Include sugars and starches • Classified according to size • Monosaccharides—simple sugars • Disaccharides—two simple sugars joined by dehydration synthesis • Polysaccharides—long-branching chains of linked simple sugars

  42. Carbohydrates Figure 2.13a–b

  43. Carbohydrates Figure 2.13c

  44. Carbohydrates Figure 2.14

  45. Important Organic Compounds • Lipids • Contain carbon, hydrogen, and oxygen • Carbon and hydrogen outnumber oxygen • Insoluble in water

  46. Lipids • Common lipids in the human body • Neutral fats (triglycerides) • Found in fat deposits • Composed of fatty acids and glycerol • Source of stored energy

  47. Lipids Figure 2.15a

  48. Lipids • Common lipids in the human body (continued) • Phospholipids • Form cell membranes • Steroids • Include cholesterol, bile salts, vitamin D, and some hormones

  49. Lipids Figure 2.15b

  50. Lipids • Cholesterol • The basis for all steroids made in the body Figure 2.15c

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