Chemistry of Life BIOL-101 Section 800RL Mr. Fusco

1. Chemistry of LifeBIOL-101 Section 800RLMr. Fusco Chapter 2: The Chemical Context of Life Chapter 3: Water and the Fitness of the Environment

2. Matter • Organisms are composed of matter • ______ is anything that takes up space or has mass • Matter is made up of elements • An ______ is a substance that cannot be broken down to other substances by chemical reactions • Organized into ____________________ • ____________ usually first letter or two • A ______ is a substance consisting of two or more elements in a fixed ratio • A compound has characteristics different from those of its elements • Example = Sodium Chloride (NaCl)

3. Fig. 2-3 Sodium chloride Chlorine Sodium Compound Example

4. Essential Elements of Life • About 25 of the 94 naturally occurring elements are essential to life • Carbon, hydrogen, oxygen, and nitrogen make up 96% of living matter • Most of the remaining 4% consists of calcium, phosphorus, potassium, and sulfur • ____________are those required by an organism in minute quantities (less than 0.01%)

5. What are You Made of? Human composition 1) Oxygen 65% 2) Carbon 18.5% 3) Hydrogen 9.5% 4) Nitrogen 3.3% 5) Calcium 1.5% 6) Phosphorus 1% 7) Potassium 0.4% 8) Sulfur 0.3% 9) Sodium 0.2% 10) Chlorine 0.2% 11) Magnesium 0.1%

6. Trace Elements • Micronutrients • Minute, “trace”, quantities • Vitally Important • Ex. cobalt, copper, chromium, fluorine, chlorine, iron, iodine, manganese, selenium and zinc • Website defining elements

7. Atoms • Each element consists of unique atoms • An ______ is the smallest unit of matter that still retains the properties of an element • Smallest particle of an element that has the characteristics of that element (elements are built from one kind of atom)

8. Atoms • Atomic ______ -protons -neutrons • Proton number (atomic number) determines the type of element • Electrons form a cloud around the nucleus • Neutron mass and proton mass are almost identical and are measured in daltons • ____________ = number of protons • ____________ = proton # + neutron #

9. Atomic Structure

10. Atomic Structure

11. Reading the Periodic Table 6 C Carbon 12.011 Atomic Number (# of protons) Atomic Symbol Element Name Atomic mass (# of protons + # of neutrons)

13. Electric Charges • The negative charge of the electron is the same magnitude as that of the proton (equal but opposite) • An atom is electrically ______ . • #protons = #electrons

14. Electron Energy Levels • ______is the capacity to cause change • ____________is the energy that matter has because of its location or structure • The electrons of an atom differ in their amounts of potential energy • An electron’s state of potential energy is called its energy level, or ____________

15. Electron Energy Levels • Electrons fill different “shells” -1st shell: up to ______ -2nd shell: up to ______ -3rdshell: up to ______ • Shells are filled from inner to outer • Atoms will take or give electrons to attain a full outer shell (______) • Atoms with full shells typically don’t react When drawing an atom like this, it is called a Bohr model.

17. Electron Distribution • Electrons help determine the chemical behavior of an atom • The periodic table of the elements shows the electron distribution for each element • ____________are those in the outermost shell, or ____________ • Specifically, the chemical behavior of an atom is mostly determined by the valence electrons • Elements with a full valence shell are chemically ______(not chemically active)

18. Ions and Isotopes • ___________ -(+) or (-) charged particle -What would have to happen for an atom to become an ion? • ___________ -atoms of the same element with different numbers of neutrons • All atoms of an element have the same number of protons but may differ in number of neutrons

19. C C C 12 13 14 6 6 6 Carbon Isotopes: What differs? ___________ 6 neutrons 7 neutrons 8 neutrons

20. Radioactive Isotopes • Occurs when nuclei of unstable isotopes break apart • Used as ______ in medicine and research • Dangers: -Nuclear explosions -Radon (2nd most frequent cause of lung cancer) • Some applications of radioactive isotopes in biological research are: • Dating fossils • Tracing atoms through metabolic processes • Diagnosing medical disorders

21. Drawing Atoms • Using the periodic table, write the following information on your atom on an index card: • Symbol • Atomic # • Atomic mass • Element name • Sketch your model (Bohr model) • Is the outermost electron shell filled • Will this element readily react with others? Why or why not?

22. Chemical Bonding • Atoms of different elements interact to form ______ • These interactions usually result in atoms staying close together, held by attractions called ____________ • Bonding gives a molecule completely different chemical properties than its parent elements • Example: ____________, NaCl (table salt) = nontoxic vs. ______ is a metal that is violently reactive with water.  If sodium comes into contact with water, the hydrogen gas that is released will actually burst into flames

23. Chemical Bond Types • 3 Types of Chemical Bonds -Covalent bond -Ionic bond -Hydrogen bond

24. Covalent Bonds • Electron ______ • Usually between 2 nonmetals • Strongest bond • Multiple covalent bonds can form if they need more than one electron to fill their outer shell ____________ = sharing of one pair of valence electrons ____________ = sharing of two pairs of valence electrons

25. Covalent Bonds • The notation used to represent atoms and bonding is called a __________________ • For example, H–H • This can be abbreviated further with a ____________________ • For example, H2

27. Covalent Bonds • Found in most compounds in organisms • A___________is agroup of atoms held together by covalent bonds having no overall charge • ________________is an atom’s attraction for the electrons in a covalent bond • The more electronegative an atom, the more strongly it pulls shared electrons toward itself • Examples: Sugars, fats, proteins, water • What is a diatomic molecule?Polyatomic?

28. Covalent Bond Types • ___________ covalent -equally shared electrons • ___________-covalent -One atom has a greater affinity for electrons in a molecule (more electronegative) -Shared electrons will spend more time around that atom -Unequally shared electrons will cause a partial electrical charge (called a _______) to form across the molecule

29. Polar vs. Non-Polar Covalent Bonds Non-Polar Covalent Bond Polar Covalent Bond 2 H atoms equally sharing electrons A dipole caused by the polar covalent bond of the water molecule.

30. Weak Bonds • Most of the strongest bonds in organisms are covalent bonds that form a cell’s molecules • Weak chemical bonds, such as ___________bonds and ___________bonds, are also important • Weak chemical bonds reinforce shapes of large molecules and help molecules adhere to each other

31. Ionic Bonding • Electron ___________ • Atoms sometimes strip electrons from their bonding partners • After the transfer of an electron, both atoms have charges • Remember, a charged atom (or molecule) is called an ___________ • The oppositely charged ions attract to form an ______________________ • An example is the transfer of an electron from sodium to chlorine

32. Ionic Bonding • Usually between 2 metals, or a metal and a nonmetal • Example: -Na (Sodium) Atomic number = 11 How many electrons in outermost shell? How many electrons to fill outer shell? -Cl (Chlorine) Atomic number 17 How many electrons in outermost shell? How many electrons to fill outer shell?

33. Ionic Bonding:Na and Cl • ______________________an electron and becomes positively charged (Na+) • ______________________an electron becoming negatively charged (Cl-) • Both atoms now become ions • ___________charges on the Na+ and Cl- ions cause them to attract each other and form an ionic bond • Na+ + Cl-  NaCl

34. Ionic Bonding:Na and Cl

35. Ionic Bonding • A ___________is a positively charged ion • An ___________is a negatively charged ion • An ionic bond is an attraction between an anion and a cation • Compounds formed by ionic bonds are called ionic compounds, or ___________ • Salts, such as sodium chloride (table salt), are often found in nature as crystals

36. Hydrogen Bonding • Water molecules have polar (charged) ends • A ___________bond forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom • Allows for hydrogen bonding with other water molecules • H-bonding holds water molecules together • Weak bonds resulting from: -attraction of ______________________H-atom on 1 water molecule to ______________________O-atom in another molecule • Resulting in water molecules clinging together • Water Movie

38. Van der Waals forces • Electrons in a molecule are in random motion around the nuclei. • The movement of electrons can cause an ___________distribution of the electron cloud, creating ___________areas of slightly positive and negative charges • When molecules come close together, the attractive forces between these positive and negative regions pull on the molecules and hold them together. • The strength of the attraction depends on the size of the molecule, the shape and its ability to attract electrons.

39. Water (Agua) • Water is the biological medium on Earth • All living organisms require water more than any other substance • Most cells are surrounded by water, and cells themselves are about ___________water • The abundance of water is the main reason the Earth is habitable • The water molecule is a ______________________: The opposite ends have opposite charges • ___________allows water molecules to form hydrogen bonds with each other

41. Properties of Water • Four of water’s properties that facilitate an environment for life are: • Cohesive/Adhesive behavior • High Specific Heat • Expansion upon freezing • Universal solvent

42. Cohesive Forces • ___________ -water molecules are attracted to other water molecules ______________________= cohesion of water molecules at the surface of a body of water • Example:Water strider bug (right) & Basilisk (aka Jesus lizard)

43. Adhesive Forces • ___________ -Water is attracted to other materials • Example:____________in a straw -water “climbs” up a straw -water molecules are attracted to the straw molecules -When one water molecule moves closer to the straw molecules the other water molecules (which are cohesively attracted to that water molecule) also move up into the straw • Plants use capillary action to draw water from the ground into themselves

44. High Specific Heat Index • Water can absorb a lot of heat before it begins to get hot since -hydrogen bonds ___________breaking -it takes much energy before bonds break, releases lots before rejoining • Example: Moderates temperature on Earth

45. High Specific Heat Index • Water absorbs heat from warmer air and releases stored heat to cooler air • Water can absorb or release a large amount of heat with only a slight change in its own temperature • ___________is a measure of the total amount of kinetic energy due to molecular motion • ______________________is the energy of motion • ___________measures the intensity of heat due to the average kinetic energy of molecules

46. Evaporative Cooling • ___________is transformation of a substance from liquid to gas • _________________________is the heat a liquid must absorb for 1 g to be converted to gas • As a liquid evaporates, its remaining surface cools, a process called ______________________ • Evaporative cooling of water helps stabilize temperatures in organisms and bodies of water • Hottest water molecules leave first, reducing the average temp. of those remaining • Examples: -Cools tropical oceans -Keeps coastal areas more moderate

47. Physical States • Which is most dense: solid, liquid, gas? • Usually solid, but in water, liquid is most dense • As a result, when water freezes it floats -hydrogen bonding What if ice did not float?

48. Insulation of Bodies of Water by Floating Ice • Ice floats in liquid water because hydrogen bonds in ice are more “ordered,” making ice less dense • Water reaches its greatest density at ___________ • If ice sank, all bodies of water would eventually freeze solid, making life impossible on Earth

49. Universal Solvent • Water dissolves more substances than any other liquid. • A ___________is a mix of 2 or more substances • A ___________is a dissolving agent • A ___________is what dissolves • Polar substances dissolve in water (like dissolves like) • An ___________solution is one in which water is the solvent • Chemical reactions of living things • Dissolving animation

50. Hydrophilic & Hydrophobic • A ___________substance is one that has an affinity for water • A ___________substance is one that does not have an affinity for water • Oil molecules are hydrophobic because they have relatively nonpolar bonds • A ___________is a stable suspension of fine particles in a liquid • Most biochemical reactions occur in water • Chemical reactions depend on collisions of molecules and therefore on the concentration of solutes in an aqueous solution