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Biology Chapter 2

Biology Chapter 2. The Chemistry of Life. I. The nature of matter-. A. Atoms-_____________ Derived from Greek word Atomos ,which means “unable to be cut” As described by _____________________,2300 years ago. Basic unit of matter. Democritus. Atoms cont’d.

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Biology Chapter 2

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  1. Biology Chapter 2 The Chemistry of Life

  2. I. The nature of matter- • A. Atoms-_____________ • Derived from Greek word Atomos,which means “unable to be cut” • As described by _____________________,2300 years ago Basic unit of matter Democritus

  3. Atoms cont’d • 100 million atoms would make a room about 1 cm long • DOES contain__________________particles that are smaller than an atom subatomic

  4. Subatomic particles

  5. Calculating subatomic particles: • PROTONS=Atomic Number=electrons(in a neutral atom) • MASS NUMBER=p + n • N=Mass-p • Electrons=p=atomic number

  6. Examples: • For Cl –atomic # =17 and mass =35 • P=17,electrons=17,neutrons =35-17=18 • For Li---It has 3 protons and 4 neutrons • Li has mass number=7 ,atomic # =3 and electrons= 3

  7. Atoms cont’d • Since atoms tend to have p=electrons ,the + and – charge balance ,making them neutral • _________________center of atom bound by STRONG FORCES. • Electrons are attracted to + nucleus ,but are held in levels by the energy of their motion nucleus

  8. B. Elements and Isotopes • _______________=PURE SUBSTANCE CONSISTING OF ONE KIND OF ATOM • More than 100 in existence but ~24 compose living things • Represented by 1 or 2 letter symbol Element

  9. Common symbols

  10. Common symbols

  11. Isotopes-atoms of the same element with a different number of neutrons----example:C-12,C-13,C-14----all averaged together for the atomic mass • Isotopes are identified by ____________________. • Radioactive Isotopes have unstable nuclei and break down at a constant rate over time… • Radioactive Isotopes uses:________________________________________ • All isotopes of an element have the same chemical properties because they have the same # of ______________-. Tracers-esp. in medical diagnosis,dating fossils,identifying and treating cancer,kill bacteria electrons Mass number

  12. Isotopes cont’d ‘WEIGHTED MASS”-ie .Atomic weight=average mass of all isotopes for an element

  13. C. Chemical Compounds=_______________________ • Shown by a chemical formula • Physical and chemical properties for an element differ a lot when they are bound in a compound • What is the ratio of H:O on H2O?_________ Substance formed by 2 or more substances in definite proportions 2:1

  14. Physical properties:______________________ • Chemical properties:_______________ Don’t change substance—color,smell.. Change substance-flammability ,corrosion

  15. D. Chemical Bonds hold together atoms in a compound • Ionic Bonds-electrons are transferred from one to another creating an electrical ,ionic charge that binds the atoms • Tends to happen between metals and nonmetals • Looking @ p.37 ,draw what happens in a NaCl bond

  16. Figure 2-3 Ionic Bonding Section 2-1 Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1 Go to Section:

  17. Figure 2-3 Ionic Bonding Section 2-1 Sodium atom (Na) Chlorine atom (Cl) Sodium ion (Na+) Chloride ion (Cl-) Transfer of electron Protons +11 Electrons -11 Charge 0 Protons +17 Electrons -17 Charge 0 Protons +11 Electrons -10 Charge +1 Protons +17 Electrons -18 Charge -1 Go to Section:

  18. Covalent Bonds-_____________________ • The moving electrons of both atoms travel in the orbits of both atoms • Double or triple bonds occur when 4 or 6 electrons are shared • ______________-smallest unit of a compound • See drawing 2-4 on p.37and draw the bond of H2O molecule Share electrons

  19. E. Van der Waals Forces_intermolecular forces that result from unequal sharing that results in tiny + or – charges in covalent bonds Help hold a molecule together a little more….see example of gecko on p.39 E. Van der Waals Forces_intermolecular forces that result from unequal sharing that results in tiny + or – charges in covalent bonds Help hold a molecule together a little more….see example of gecko on p.39

  20. Rapid movement of electrons can create regions of tiny (+) and (-) charges/As some molecules are close together,slight attraction between oppositely charged regions of nearby molecule-esp. when molecule is large Rapid movement of electrons can create regions of tiny (+) and (-) charges/As some molecules are close together,slight attraction between oppositely charged regions of nearby molecule-esp. when molecule is large

  21. II. Properties of water • Single most abundant compound in most living things • A. The Water Molecule • _____________-because of an uneven distribution of electrons between O and H atoms • O side is more – pole because it has more electrons • It is ,essentially ,neutral ,but has a more – and more + end • Because of this polarity water molecules can attract one another Polar

  22. Polar charges are written in ( ) to show they are weaker than ionic charges • H bonds not strong ,but water can form___________ H bonds…..causing many of its properties-/bonding with itself O,N, and F multiple

  23. A single water molecule can be involved in as many as 4 H-bonds __________________-attraction between molecules of the same substance…water is cohesive Cohesion

  24. example-surface tension allows spiders to walk on water cohesion

  25. ___________________-attraction between molecules of different substances-example-water creating meniscus as attaches to sides of graduated cylinder • capillary action and how it is used in nature __________________ Draws water out of roots and up into stems and leaves adhesion

  26. adhesion

  27. HEAT CAPACITY---because of H-bonds ,takes a lot of heat to get water molecules moving faster, creating high heat capacity….helping organisms maintain body temp’s

  28. B. Solutions and Suspensions • Water is often in a ________________________,where 2 or more elements or compounds are PHYSICALLY combined mixture

  29. Figure 2-9 NaCI Solution Section 2-2 Cl- Cl- Na+ Na+ Water Water Go to Section:

  30. Figure 2-9 NaCI Solution Section 2-2 Cl- Cl- Na+ Na+ Water Water Go to Section:

  31. 2 types of solutions • __________________mixture where components evenly distributed • Ions are surrounded by water molecules and evenly distributed • _____________-substance dissolved • ______________-substance that does dissolving • ____________________-mixtures of water and non dissolved materials—blood cells in a suspension of water in vessels solvent solute suspension Solutions

  32. Acids,Bases and pH- • Water molecule can react to form ions.Draw reaction as shown @ bottom of p.42: • _________________indicates concentration of H ions in solution pH

  33. Each step represents a power of 10example-pH of 5 has 10 x as many H+ ions as same qty of ph 6 • ______________-higher concentrations of H+ ions and pH <7 • _______________-alkaline-lower H+ concentration and pH>7 • ________________weak acids or bases that react w/ strong ones to prevent sharp pH changes acids bases buffers

  34. Buffers are dissolved in life’s fluids ,playing an important role in maintaining homeostasis in organisms

  35. pH Scale Section 2-2 Oven cleaner Bleach Ammonia solution Increasingly Basic Soap Sea water Human blood Neutral Pure water Milk Normal rainfall Acid rain Increasingly Acidic Tomato juice Lemon juice Stomach acid Go to Section:

  36. Interest Grabber Life’s Backbone Section 2-3 • Most of the compounds that make up living things contain carbon. In fact, carbon makes up the basic structure, or “backbone,” of these compounds. Each atom of carbon has four electrons in its outer energy level, which makes it possible for each carbon atom to form four bonds with other atoms. • As a result, carbon atoms can form long chains. A huge number of different carbon compounds exist. Each compound has a different structure. For example, carbon chains can be straight or branching. Also, other kinds of atoms can be attached to the carbon chain. Go to Section:

  37. Interest Grabber continued Section 2-3 • 1. On a sheet of paper, make a list of at least ten things that contain carbon. • 2. Working with a partner, review your list. If you think some things on your list contain only carbon, write “only carbon” next to them. • 3. If you know other elements that are in any items on your list, write those • elements next to them. Go to Section:

  38. Carbohydrates Lipids Nucleic acids Proteins Sugars and starches Fats and oils Nucleotides Amino Acids Carbon, hydrogen, oxygen Carbon, hydrogen, oxygen Carbon, hydrogen,oxygen, nitrogen, Carbon,hydrogen, oxygen, nitrogen, phosphorus Concept Map Section 2-3 Carbon Compounds include that consist of that consist of that consist of that consist of which contain which contain which contain which contain Go to Section:

  39. III. Carbon Compounds • In the 1800’s,chemists thought compounds created by living things –organic compounds-were much different than others • In 1838 a German chemist made the organic compound,urea ,from nonorganic ammonium cyanate…Thus principles of chemistry governing nonliving could be applied to living things • _________________________is actually the study of almost all C-compounds-many not having anything to do w/ living things. Organic Chemistry

  40. A. The Chemistry of Carbon • Why is carbon special?---1) It has 4 valence electrons and can make 4 bonds 2)It can bond w/ many other elements. Includes H,O, • 3)C can bond to other C’s in single,double or triple bonds • 4)C can form chains and rings ACETYLENE METHANE

  41. butadiene Isooctane • Forms millions of different complex structures. BENZENE RING

  42. B. Macromolecules • “Giant molecules found in organisms “ • Formed by _____________________,in which large compounds are built by joining smaller ones. • _______________-small units –join to form ______________-LARGE compounds monomers polymerization polymers

  43. The 4 groups of macromolecules are____________________________ Carbohydrates,nucleic acids,lipids and proteins

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