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2013 s bio 101 chapter 2 basic chemistry

2013 s bio 101 chapter 2 basic chemistry






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  • http://dsc.discovery.com/news/2007/10/29/beetle-combustor.html

2013 s bio 101 chapter 2 basic chemistry 2013 s bio 101 chapter 2 basic chemistry Presentation Transcript

  • Objectives for this week…  Generate an empirically evidenced and logical argument.  Distinguish a scientific argument from a non-scientific argument.  Recognize methods of inquiry that lead to scientific knowledge.  List features that distinguish living organisms from nonliving matter.  Explain what is meant by the term diversity, and speculate about what caused the great diversity of life forms on Earth.  List as many steps of the scientific approach to understanding a problem as you can.  Know the various types of chemical bonds, the circumstances under which each forms, and the relative strength of each type  Understand the essential chemistry of water, the relationships of acids, bases, and salts.
  • Why do we need to learn about Chemistry? Chapter 2 Basic Chemistry Chemistry: “The study of matter & the changes it undergoes.” -Chang, R. (2007). Chemistry. 9th ed. McGrawHill: New York
  • Life is made of chemicals!
  • Why Chemistry? Life uses chemical reactions!
  • Why Chemistry? Life uses chemical reactions!
  • What are we going to talk about today? Chemical elements Compounds and molecules Chemistry of water Acids and bases
  • Protons Electrons Neutrons Chemical Elements • Matter: anything that takes up space and has mass (solids, liquids, gases) • All matter is made of elements: cannot be broken down Oxygen An element! + + + + + + + + - - -- - - - - Atom: smallest unit of an element Water Not an element! Hydrogen John Dalton
  • Chemical Elements CHNOPS = 95% body weight of organisms
  • Chemical Elements Helium
  • Electrons are attracted to the positively charged nucleus Chemical Elements (-)(+) Most stable Less stable Valence shell: Outer electron shell Valence electrons: # of electrons in valence shell Octet rule: outer shell is most stable with 8 electrons
  • Chemical Elements • Isotopes – Same # of protons and electrons – Different # of neutrons • Ions – Different # of electrons – Have charges, instead of being neutral Na Na+
  • Chemical Elements • Way to organize the elements • Groups - similar characteristics – Same valence electrons • Periods – same # valence shells • Atomic mass – Average mass for all the isotopes – Slightly different than mass number Periodic Table
  • Chemical Elements Handwritten Periodic Table Which isotope you are talking about Average mass of all isotopes
  • Chemical Elements Carbon Isotopes – How many neutrons? 6 7 8 Unstable – radioactive!
  • Chemical Elements • Radioactivity - releases energy (as well as other particles) • Radioactive isotopes can be used as medical tracers (low levels) • High levels can be used to kill bacteria and cancer
  • What are we going to talk about today? Chemical elements Compounds and molecules Chemistry of water Acids and bases
  • Compounds and Molecules • Compound vs. molecule • Compound 2 different elements • Molecule has same elements • In Biology, everything is a molecule!  http://dl.clackamas.edu/ch104-03/molecule.htm Water Molecular Oxygen
  • Compounds and Molecules • Ionic Bonding – Transfer of electrons from one atom to another – Causes (+) and (-) charged ions – Attracted to each other – Salts: solid substances that usually separate and exist as individual ions in water
  • Compounds and Molecules • Covalent Bonding – Two atoms share electrons to fill outer electron shell – Single, double, triple bonds – Non-polar covalent bond = equal electron sharing – Polar covalent bond = unequal electron sharing  water!!
  • Which do you think is the strongest, ionic or covalent bonds? Why?
  • What are we going to talk about today? Chemical elements Compounds and molecules Chemistry of water Acids and bases
  • Chemistry of Water Water (H2O) is polar covalent Oxygen is very electronegative Hydrogen bonding between molecules
  • The discovery of liquid water under the frozen surface of a distant moon in our solar system has caused scientists to speculate on the possibility of life on that moon. Researchers hold no hope of any life form existing on any planet or moon in the absence of water. Why?
  • Chemistry of Water • Properties 1. High heat capacity 2. High heat of evaporation 3. Solvent 4. Cohesion & adhesion 5. Frozen water is less dense than liquid water
  • Chemistry of Water High Heat Capacity Good for organisms that this occurs slowly!
  • Chemistry of Water High Heat of Evaporation
  • Chemistry of Water Water is a Solvent • Universal solvent • Hydrophilic – molecules that can attract water (ions, polar molecules) • Hydrophobic – molecules that cannot attract water (nonpolar molecules, neutral atoms)
  • Chemistry of Water Cohesion & Adhesion
  • Chemistry of Water Frozen water is less dense than liquid water
  • Review: Chemistry of Water • Polar covalent bond within the molecule • Hydrogen bonds between molecules • 5 Properties 1. High specific heat 2. High heat of vaporization 3. Is a solvent 4. Cohesion and adhesion 5. Frozen water is less dense than water
  • What are we going to talk about today? Chemical elements Compounds and molecules Chemistry of water Acids and bases
  • Acids and Bases When water dissociates (ionizes)  equal # of hydrogen ions and hydroxide ions Only a few at a time do this
  • Acids and Bases Acids • Dissociate in water  releasing H+ • Strong acid almost completely dissociates HCl  H+ + Cl- Bases • Uptake H+ or release OH- • Strong base almost completely dissociates NaOH  Na+ + OH-How do we measure this?
  • Acids and Bases • pH scale: measurement scale for hydrogen ion concentration • >7 basic • <7 acidic • =7 neutral • Log scale – each increase in number = 10X increase 100X more acidic than water 10,000,000X more acidic than water
  • Acids and Bases • Buffers: chemical or combination of chemicals that keep pH within normal limits – Blood pH needs to stay about 7.4 – At 7, acidosis – At 7.8, alkalosis H2CO3 H+ HCO3 - dissociates re-forms
  • Acids and Bases • Acid precipitation (deposition) has a pH <5 • Sulfur dioxide and nitrogen oxides from fossil fuel emissions such as coal, oil, and gasoline • Lakes, forests, structures
  • What are we going to talk about today? Chemical elements Compounds and molecules Chemistry of water Acids and bases Any Questions?
  • Review Questions About 25 of the 92 natural elements are known to be essential to life. Which four of these 25 elements make up approximately 96% of living matter? A) carbon, sodium, chlorine, nitrogen B) carbon, sulfur, phosphorus, hydrogen C) oxygen, hydrogen, calcium, sodium D) carbon, hydrogen, nitrogen, oxygen E) carbon, oxygen, sulfur, calcium
  • Review Questions How do isotopes of the same element differ from each other? A) number of protons B) number of electrons C) number of neutrons D) valence electron distribution E) amount of radioactivity
  • Review Questions A covalent chemical bond is one in which A) electrons are transferred from one atom and to another atom so that the two atoms become oppositely charged. B) protons and neutrons are shared by two atoms. C) outer-shell electrons of two atoms are shared. D) outer-shell electrons of one atom are transferred to the inner electron shells of another atom. E) the inner-shell electrons of one atom are transferred to the outer shell of another atom.
  • Review Questions Protons = Neutron = Electrons = 7 8 7 Atomic Number Mass Number
  • Review Questions Ca 2+ Protons = Neutron = Electrons = 20 20 18
  • Review Questions Atomic Mass Atomic Number Atomic Symbol
  • Resources • Bombardier beetle – http://www.pnas.org/content/96/17/9705.full • History of the Atom – http://www.chemheritage.org/discover/chemistry -in-history/themes/index.aspx