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CHEMISTRY of LIFE

CHEMISTRY of LIFE. Chapter 2. The Nature of Matter. Important Terms. Atom : basic unit of matter Fun Fact – 100 million atoms make can fit across your pinkie nail! Subatomic Particles : make up an atom Protons – p + Positively charged particles Neutrons – n 0 neutral particles

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CHEMISTRY of LIFE

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  1. CHEMISTRY of LIFE • Chapter 2

  2. The Nature of Matter

  3. Important Terms • Atom: basic unit of matter • Fun Fact – 100 million atoms make can fit across your pinkie nail! • Subatomic Particles: make up an atom • Protons – p+ • Positively charged particles • Neutrons – n0 • neutral particles • Electrons – e- • negatively charged particles • n0 and p+ are found in the nucleus of the atom • e- are found orbiting the nucleus

  4. Diagram of an Atom Yellow = protons Orange = neutrons Grey = electrons

  5. More Important Terms • Element: a pure substance that consists entirely of one type of atom • All elements are found on the periodic table • Elements are represented by symbols • Ca H Ar I Mg K • Compound: a substance formed by the chemical combination of 2 or more elements (same or different) in definite proportions. • Represented by formulas • H2O C6H12O6 CO2 N2 O2

  6. Counting Atoms • Formulas tell us how many of each atom there is in the compound • H2O • How many hydrogens? • 2 • How many oxygens? • 1 • C6H12O6 • How many carbons? Hydrogen? Oxygen? • 6, 12, 6

  7. One More Important Term • Molecule: smallest unit of a compound • H2O only 1 molecule of water • 2 H2O 2 molecules of water • CO21 molecule of carbon dioxide • 5 CO25 molecules of carbon dioxide • Let’s count the atoms again. • 5 H2O • How many hydrogen? • 1 molecule has 2 H but there are 5 molecules • 2 x 5 = 10 • How many oxygen? • 1 x 5 = 5 • 3 C6H12O6 • C = 18, H = 36, O = 18

  8. The Periodic Table

  9. Let’s Look at Carbon! Find Carbon on your periodic table! 6 Atomic Number C Symbol Carbon Element Name 12.0107 Atomic Mass

  10. What Does the Periodic Table Tell Us? • Atomic # = # of p+ (You must know this!) • Atomic # never changes! • Atomic # of Carbon will always be 6! • Atomic Mass tells us the mass of each element. • The protons and neutrons make up the mass! • Mass # = the atomic mass rounded off • Atomic mass of Carbon is 12.0107 so the mass # is 12.

  11. How do we figure out n0 and e-? • p+ = e- unless its an ion! • Ion: a positively or negatively charged atom • Cl- Na+ Al+3 S-2 • Mass # = p+ + n0 • In other words: mass # - p+ = n0 • You must know these equations!!!!

  12. Let’s Practice! • Ex 1: Carbon • Atomic # = • Atomic Mass = • Mass # = • p+ = • n0 = • e- = • Ex 2: Aluminum Atomic # = Atomic Mass = Mass # = p+ = n0 = e- = 6 13 12.0107 26.981538 12 27 6 13 12-6 = 6 27-13 =14 6 13

  13. Let’s Practice! • Ex 3: Gold • Atomic # = • Atomic Mass = • Mass # = • p+ = • n0 = • e- = • Ex 4: Barium Atomic # = Atomic Mass = Mass # = p+ = n0 = e- = 79 56 196.96555 137.327 197 137 79 56 197-79 = 118 137-56 = 81 79 56

  14. Chemical Bonds • Ionic Bonds • Covalent Bonds • Hydrogen Bonds

  15. Bonding • When looking at bonding between atoms, we are concerned about the number of e- found in the outer orbit of each atom. • We can tell how many e- are in the outer orbit by looking at where the element is located on the periodic table.

  16. 1e- in outer shell 8e- 2e- 3e- 4e- 5e- 6e- 7e-

  17. Lewis Dot Diagrams • When drawing out bonds between atoms, we use Lewis Dot Diagrams. • LDDs show the # of e- in the outer orbit by using the symbol surrounded by dots. • Examples: • Sodium is found in the 1st column so it has only 1 e- in outer shell  • Chlorine is found in the 7th column so it has 7 e- in its outer orbit  Na Cl

  18. Now you practice! Al N Ar

  19. Ionic Bonds • Ionic bonds occur when e- are transferred from one atom to another • Ions: charged atom due to a loss or gain of e- • Loss of e- results in a positive charge… why? • Gain of e- results in a negative charge… why? • Goal: to make all atoms “happy” • All atoms want 8 e- in outer shell • One exception = H only wants 2 • Without a full outer shell, an atom is very “unhappy” or unstable.

  20. Ionic Bonds • Ex: NaCl (Sodium Chloride) • In order for both Na and Cl to be “happy” Na will give its 1 e- to Cl. • How does that make Na “happy”? • Na loses an e- and becomes Na+ • Cl gains an e- and becomes Cl- Na Cl

  21. Let’s Practice Ionic Bonds! • Ex 1: Cl- • Atomic # = • Atomic Mass = • Mass # = • p+ = • n0 = • e- = • Ex 2: Na+ Atomic # = Atomic Mass = Mass # = p+ = n0 = e- = 17 11 35.4527 22.989770 35 23 17 11 35-17=18 23-11 =12 17+1=18 11-1=10

  22. Now you try! • Ex 3: Al+3 • Atomic # = • Atomic Mass = • Mass # = • p+ = • n0 = • e- = • Ex 4: S-2 Atomic # = Atomic Mass = Mass # = p+ = n0 = e- = 13 16 26.981538 32.066 27 32 13 16 27-13=14 32-16=16 13-3=10 16+2=18

  23. Covalent Bonds • Covalent Bonds occur when e- are shared between 2 atoms. • Goal: to make all atoms “happy” • All atoms want 8 e- in outer shell • One exception = H only wants 2 • You can have single (2 e-), double (4 e-), and triple (6 e-) bonds. • Again we will use Lewis Dot Diagrams!

  24. Let’s Draw Covalent Bonds • Ex: F2 • Ex: H2 F F H H

  25. Let’s Draw Covalent Bonds • Ex: N2 • Ex: O2 N N O O

  26. Let’s Draw Covalent Bonds • Ex: H2O • Ex: NH3 H O H H N H H

  27. Properties of Water

  28. Polarity • Polarity: the unequal distribution/sharing of e- • Some atoms have a stronger “pull” and therefore hog the e- • Causes an angular shaped molecule

  29. Hydrogen Bonding • Due to the partial (+) and (-) charges of H20 molecules, there is an attraction between H20 molecules • (+) hydrogens are attracted to (-) oxygens of other molecules • This causes H-bonds between H and O of different H20 molecules

  30. Hydrogen Bonds

  31. Cohesion • Cohesion: attraction of molecules of the same substance • Cohesion causes surface tension • Allows water to form beads • Allows bugs to “walk” on water

  32. Adhesion • Adhesion: attraction of molecules between different substances • Attraction between water and glass forms a meniscus • Allows for capillary action in plants – water can move from the roots all the way to the top of the plant

  33. Solutions and Suspensions • Mixtures are composed of 2 or more elements or compounds that are physically combined (not chemically combined) • Salt and pepper, water and oil, sugar and sand • Solution: even distribution of all components in the mixture (salt water, sugar water) • Solute – the substance being dissolved • Solvent – the substance doing the dissolving • Suspension: mixture of nondissolved material in water (oil and water)

  34. Solution

  35. Suspensions

  36. Acids, Bases, and pH

  37. Let’s Start with Water • H2O H+ + OH- • H+ is a hydrogen ion • OH- is a hydroxide ion • Water is neutral because H+ = OH- • When the H+ and OH- are unequal, the result is an acid or a base.

  38. The pH Scale (power of hydrogen) • pH scale indicates the concentration of H+ in a solution. • Ranges from 0-14 • 7 = neutral = pure water • H+ = OH- • Below 7 = Acid • H+ > OH- • Above 7 = Base • H+ < OH- • The lower the pH the greater the acidity. • The higher the pH the greater the basicness.

  39. Neutralization Reactions • We can mix an acid and base together in specific proportions to theoretically make water. • When an acid (more H+) is added to base (more OH-), eventually the H+ will balance out the OH-, which makes the substance neutral.

  40. Chemical Reactions

  41. Chemical Reactions (Chem. Rxn) • Chem rxn: a process that changes one set of chemicals into another • Reactants: compounds that enter into a rxn • Products: compounds that are a result of a rxn • Chem rxn involve changes in bonds • CO2 + H2O H2CO3 • 6 CO2 + 6 H2O C6H12O6 + 6 O2

  42. Energy in Rxns • Energy is stored in bonds. • Rxns that release energy occur spontaneously. • Energy is released when the bond is broken. • Rxns that absorb energy will only occur with a source of energy • Activation energy: energy required to start a rxn

  43. Catalysts and Enzymes • Catalyst: a substance that speeds up the rate of a chem rxn • Lowers activation energy • Enzyme: protein that acts as a biological catalyst • Speeds up rxns in cells • Enzymes are very specific to the process it has to speed up.

  44. Organic Molecules • Carbohydrates • Lipids • Proteins • Nucleic Acids

  45. BioChemistry The cell is a complex "ChemicalFactory" made up of the same elements that show up over and over again in different ways. These elements can also be found in the non-living environment. Of all the elements found on earth, there are four main ones that are present in the greatest percentages (amounts) in living things. They are: C- carbon H- hydrogen O- oxygen N- nitrogen

  46. Organic v. Inorganic ___________ Compounds • compounds that do not contain both ________ and ________. • organisms do require certain inorganic substances to survive ___________ Compounds • compounds that contain both _________ and ____________. • called organic because they are mainly found in living things

  47. Macromolecules • Big! (hence "macro") • Made of a few, common atoms • Accomplish all life functions • Put together in a special way • Can be incredibly complex

  48. Organic Compounds • Carbohydrates - provide _______ for living things • Lipids - stored ________, structural part of cell membranes • Proteins - necessary for _________ and __________ of tissues, found in cell membranes, ___________, and other important functions. • Nucleic Acids (_____/_____)-molecules of genetic code

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