Chapter 2 - Basic Chemistry

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Chapter 2 - Basic Chemistry

  1. 1. The Chemistry of LifeChapter 2
  2. 2. Chemistry All living things depend on chemistry ◦ The structure and function of all living things are governed by the laws of chemistry Why is it important to understand chemistry in biology? Biologists study chemistry because all living things are made of the same kinds of matter that make up nonliving things
  3. 3. Section 1COMPOSITION OFMATTER
  4. 4. Matter Everything in the universe is made of matter Matter is anything that occupies space and has mass Mass is the quantity of matter an object has
  5. 5. Elements and Atoms Elements are substances that cannot be broken down chemically into simpler kinds of matter Information about elements is summarized on a chart called the periodic table The simplest particle of an element that retains all of the properties of that element is an atom
  6. 6. Elements and Atoms
  7. 7. The nucleus Nucleus – the central region that makes up the bulk of the mass of the atom ◦ Consists of:  Protons – positively charged particles  Neutrons – particles with no charge
  8. 8. Electrons Net electrical charge of an atom is zero Electrons – small, negatively charged particles ◦ Move around the nucleus at very high speeds ◦ Located in orbitals – regions around a nucleus that show the probable location of an electron  Orbitals correspond to specific energy levels
  9. 9. Elements Atomic Number = number of protons in an element Mass Number = total number of protons and neutrons in the atom
  10. 10. Isotopes Atoms of the same element that have a different number of neutrons Average atomic mass of an element takes into account the relative amounts of each isotope in the element
  11. 11. PRACTICE In groups, we are going to practice drawing elements on white boards Group 1 – Draw and identify the element that has 6 protons, 6 neutrons, and 6 electrons Group 2 – Draw and identify the element that has 7 protons, neutrons, and electrons
  12. 12. PRACTICE Group 3 – 8 protons, neutrons, and electrons Group 4 – 15 protons, 16 neutrons, and 15 electrons Group 5 – 16 protons, neutrons, and electrons Group 6 – 11 protons, 12 neutrons, and 11 electrons Group 7 – 13 protons, 14 neutrons, and 13 electrons Group 8 – 19 protons, 20 neutrons, and 19 electrons Group 9 – 26 protons, 29 neutrons, and 26 electrons
  13. 13. Compounds Compounds are made up of atoms of two or more elements in fixed proportions ◦ Chemical formula shows the kinds and proportions of atoms of each element that forms a particular compound (Ex: H20) Compounds usually very different from the elements that form them ◦ Sodium – soft metal ◦ Chlorine – poisonous gas ◦ Sodium chloride – table salt
  14. 14. Compounds Most atoms are not stable in their natural state, so they tend to react with other atoms in different ways to become more stable Chemical bonds are the attractive forces that hold atoms together
  15. 15. Ionic Bonds Covalent Bonds Formed when one or  Formed when electrons more electrons are are shared between transferred from one atoms atom to another ◦ Single, double, and triple bonds Ion – atom or molecule with an electrical charge  Molecule – simplest part (Na+, Cl-) of a substance that retains all of the properties of that substance and can exist in a free state Chemical Bonds
  16. 16. Section 2ENERGY
  17. 17. Energy All living things use energy Amount of energy in the universe stays the same Can change from one form to another Transfer of energy is very important in biology
  18. 18. Energy and Matter Energy – the ability to do work ◦ Occurs in various forms and one form of energy can be changed to another form Important forms of energy in biological systems ◦ Chemical, thermal, electrical, and mechanical
  19. 19. States of Matter The atoms and molecules in any substance are in constant motion The motion and spacing between atoms or molecules determine the substances state: solid, liquid, or gas
  20. 20. States of Matter
  21. 21. States of Matter http://www.harcourtschool.com/activity /states_of_matter/
  22. 22. Energy and ChemicalReactions Chemical Reaction – one or more substances change to produce one or more different substances ◦ Energy is absorbed or released when chemical bonds are broken and new ones are formed ◦ Living things undergo many thousands of chemical reactions every day
  23. 23. Energy and ChemicalReactions  Reactants – substances or molecules that participate in a chemical reaction  Products – substances that form in a chemical reaction
  24. 24. Energy and ChemicalReactions Metabolism – the sum of all the chemical reactions that occur in an organism ◦ Energy your body needs is provided by sugars, proteins, and fats found in foods ◦ Body continuously undergoes chemical reactions to break down stored energy from foods into substances your body can use for energy
  25. 25. Activation Energy Activation Energy – the amount of energy needed to start a chemical reaction Catalysts – chemical substances that reduce the amount of activation energy that is needed for a reaction to take place ◦ Enzymes – biological molecule that speeds up metabolic reactions without being permanently changed or destroyed
  26. 26. Activation Energy
  27. 27. Section 3WATER AND SOLUTIONS
  28. 28. Water and Solutions Chemical reactions of all living things take place in the watery environment of the cell Water has several unique properties that make it one of the most important compounds found in living things
  29. 29. Polarity Polar – compounds with an uneven distribution of positive and negative charges
  30. 30. Solubility of Water The polar nature of water allows it to dissolve polar substances, such as sugars, ionic compounds, and some proteins Water does not dissolve nonpolar substances such as fats like oil
  31. 31. Solubility of Water
  32. 32. Hydrogen Bonding  The polar nature of water causes water molecules to be attracted to one another  Hydrogen bond – the force of attraction between a hydrogen molecule with a partial positive charge and another atom or molecule with a partial or full negative charge
  33. 33. Cohesion Adhesion An attractive force that  An attractive force holds molecules of a between two particles of single substance different substances together Cohesion and Adhesion
  34. 34. Capillary Action Attraction between molecules that results in the rise of the surface of a liquid when in contact with a solid Cohesion and Adhesion
  35. 35. Questions How are cohesion and adhesion similar? How are they different? How do they contribute to capillarity?
  36. 36. Density of Ice Solid water is less dense than liquid water ◦ This is opposite of all other substances Hydrogen bonding causes ice crystals to have large amounts of open space
  37. 37. Why is it important that ice isless dense than water? When bodies of water freeze, they freeze from the top down Ice insulates the water below from the cold air, which allows fish and other aquatic animals to survive under the icy surface
  38. 38. Solutions Solution – a mixture in which one or more substances are uniformly distributed in another substance ◦ Solute – substance dissolved in the solvent (may be ions, atoms, or molecules) ◦ Solvent – substance in which the solute is dissolved Sugar dissolved in water – which one is the solvent and which is the solute?
  39. 39. Solutions Solutions can be composed of various proportions of a given solute in a given solvent Concentration of a solution is the amount of solute dissolved in a fixed amount of the solution A saturated solution is one in which no more solute can dissolve
  40. 40. Solubility of Water
  41. 41. Solutions Aqueous solutions – solutions in which water is the solvent ◦ Important to living things  Marine microorganisms spend their lives in the sea  Most nutrients plants need are in aqueous solutions in moist soil  Body cells exist in an aqueous solution and are filled with aqueous solution
  42. 42. Important Properties of WaterProperty What It Does/Means ImportanceCohesion Water molecules stick Movement of water in plants, together surface tensionAdhesion Water sticks to another capillarity substanceHigh heat Absorb and release large Stabilizes global temps, keepcapacity amounts of heat energy cells at even temps without a big change in tempSolvent Water can dissolve many Marine organisms, plant different substances nutrients, body cells
  43. 43. Acids and Bases What do the words acid and base mean?
  44. 44. Ionization of Water As water molecules move, they bump into each other Some of these collisions are strong enough to result in a chemical change One water molecule loses a proton while another gains a proton
  45. 45. Ionization of Water
  46. 46. Ionization of Water H3O+ : Hydronium Ion OH- : Hydroxide Ion Acidity or alkalinity is a measure of the relative amounts of hydronium ions and hydroxide ions dissolved in a solution
  47. 47. Acids Bases Number of hydronium  Number of hydronium ions (H3O+ ) GREATER ions (H3O+ ) LESS than than the number of the number of hydroxide hydroxide ions (OH-) ions (OH-) Tend to have a sour taste  Alkaline  Bitter taste Acids and Bases
  48. 48. pH  pH scale – scale for comparing the relative concentrations of hydronium ions and hydroxide ions in a solution  Ranges from 0 to 14  Change in 1 pH unit is a 10-fold change in acidity or alkalinity
  49. 49. Buffers Buffers are chemical substances that neutralize small amounts of either an acid or a base added to a solution Control of pH is important for living systems Enzymes can function only within a very narrow pH range

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